EP1925813B1 - Fuel injector with a measuring device - Google Patents

Fuel injector with a measuring device Download PDF

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Publication number
EP1925813B1
EP1925813B1 EP07115363A EP07115363A EP1925813B1 EP 1925813 B1 EP1925813 B1 EP 1925813B1 EP 07115363 A EP07115363 A EP 07115363A EP 07115363 A EP07115363 A EP 07115363A EP 1925813 B1 EP1925813 B1 EP 1925813B1
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EP
European Patent Office
Prior art keywords
nozzle
injector
fuel injector
nozzle needle
fuel
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Not-in-force
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EP07115363A
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German (de)
French (fr)
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EP1925813A1 (en
Inventor
Patrick Mattes
Holger Rapp
Kai Sutter
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Robert Bosch GmbH
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Robert Bosch GmbH
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Publication of EP1925813A1 publication Critical patent/EP1925813A1/en
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Publication of EP1925813B1 publication Critical patent/EP1925813B1/en
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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M65/00—Testing fuel-injection apparatus, e.g. testing injection timing ; Cleaning of fuel-injection apparatus
    • F02M65/005—Measuring or detecting injection-valve lift, e.g. to determine injection timing
    • 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
    • F02M2200/24—Fuel-injection apparatus with sensors

Definitions

  • the present invention relates to a fuel injector for an internal combustion engine according to the preamble of claim 1.
  • Such a fuel injector is for example by the DE-A-31 37 761 known.
  • Fuel injectors of the type of interest here find particular application in internal combustion engines, which use such injectors to allow a metered injection of the fuel to be burned in an internal combustion engine.
  • Internal combustion engines may be embodied with various types of fuel injectors, wherein fuel injectors may be differentiated into those referred to as magnetically operated injectors, and those which may be referred to as piezoelectrically operated injectors.
  • Magnetically operated injectors include an electromagnet which can move an armature and actuate a solenoid valve assembly via a push rod. The opening and closing movement of the Bewegunns worn relates to a valve piston, the lifting movement is transmitted in a movement axis to a nozzle needle. The nozzle needle opens and closes the fuel flow through small injection bores which are attached to the nozzle body of the fuel injector and inject the fuel into a combustion chamber.
  • piezoelectrically operated injectors have a piezoelectric actuator in order to trigger the opening and closing movement of the nozzle needle via a downstream valve arrangement.
  • the movement device in the case of piezoelectrically operated injectors can therefore be limited to the opening and closing movement of the nozzle needle, wherein the movement device carries out an opening and closing movement by means of the valve arrangement arranged downstream of the piezoactuator by a corresponding fluid admission.
  • a solenoid operated injector which is designed for an injection system of an internal combustion engine with a solenoid valve, which controls the outflow of fuel through a spillway of a valve control chamber, said solenoid valve means for closing the discharge channel, one of an electromagnet actuated and with the means For closing the drainage channel operatively connected armature and a first valve spring and a second valve spring and a first Hubendanschlag has.
  • the first valve spring acts on the armature with a larger spring force in the closing direction, from the closed position of the solenoid valve to reach the first Hubendanschlags the second valve spring acts on the armature in the opening direction with a smaller spring force.
  • a respective spring is arranged on each side of the armature in order to build the fuel injector compact and to achieve an improved performance at different frequencies.
  • a fuel injector of the type disclosed herein does not offer the ability to measure the movement of the armature to positively influence the possible sensing of the solenoid with the sensed measurement data to optimize performance, particularly with regard to injected fuel quantity and timing of fuel injection ,
  • a fuel injector in the manner of a piezoelectrically operated injector.
  • the fuel injector relates to a common rail injector for injecting fuel into a combustion chamber of an internal combustion engine.
  • the fuel injector includes an injector housing having a fuel inlet communicating with a central fuel high pressure source external to the injector housing and with a pressure space within the injector housing from which high pressure fuel is injected in response to the position of a control valve.
  • a lifting movement of a nozzle needle which is guided within a guide bore in a nozzle body.
  • the nozzle needle reaches a Hubendanschlag in the opening time, and may possibly rebound from this or trigger a swinging motion.
  • the nozzle needle can trigger a vibration behavior even at the closing time, in which it closes the injection holes in the tip for injecting the fuel into the combustion chamber.
  • the vibration behavior is always initiated exactly when the nozzle needle or the Movement device of the fuel injector reaches the Hubendanschlag or the closing seat.
  • a check or a feedback of the opening and closing behavior of the nozzle needle for controlling the piezoelectric actuator to trigger the opening and closing movement of the nozzle needle is not possible. Only a driving of the piezoelectric actuator can be changed, wherein a feedback of the opening and closing movement of the nozzle needle can not be evaluated.
  • measuring devices for detecting the movement of the movement devices within a fuel injector known, however, which are unsuitable for accurate detection of the time to reach the Hubendanschlags or the end stop in the closing seat of the nozzle needle or the movement device.
  • These measuring devices are based on a capacitive distance measurement, which is not suitable for measuring larger strokes of a movement device within a fuel injector.
  • a fuel injector with a measuring device for internal combustion engines with inwardly opening valve needle is known, in which the closing spring chamber an induction coil is arranged, which together with an affected by the valve needle anchor a signal generator for a meter for determining the start of injection and possibly further data of the injection process forms.
  • the air gap of the magnetic circuit of the induction coil is formed between the armature and a coil core, against which the armature moves during the opening stroke of the valve needle.
  • This measuring arrangement is particularly suitable for measuring circuits in which a DC voltage is applied to the induction coil and the voltages induced in the induction coil as a result of the air gap changes are superimposed on the applied DC voltage.
  • the fuel injector is designed as a piezoelectrically operated injector with a fluidically actuated nozzle needle. Consequently, the measuring body in the form of z. B. a magnetic yoke in height of the nozzle needle, wherein the nozzle needle is received longitudinally movably in a nozzle body, so that according to a possible embodiment, the measuring device is installed in the nozzle body itself, and the magnetic yoke surrounds the nozzle needle or with the nozzle needle moving parts.
  • Piezo-electrically driven injectors do not have a valve piston which extends through the injector itself in an elongated direction. However, an accurate measurement of the stroke of the nozzle needle on or with the nozzle needle itself with the measuring device is possible.
  • the nozzle needle adjoins a nozzle needle control chamber at the end, which is sealed with a sealing sleeve, wherein the measuring device is formed by the sealing sleeve and the change in geometry formed in the direction of movement of the nozzle needle by the needle adjacent to the nozzle needle control chamber end of the nozzle needle.
  • the measuring device and the sealing sleeve can be designed to seal the nozzle needle control chamber as the only structural component.
  • a quasi - diameter jump serves the end face of the nozzle needle itself, i. There is a "diameter jump to zero".
  • the measuring device In order to arrange the measuring device stationary, this is installed either in the injector body or in the nozzle body.
  • the injector body and the nozzle body respectively form the holder body fixed part of the injector, wherein the injector body and the nozzle body itself influence the inductance of the measuring device as a magnetic material.
  • the field-leading holding body-fixed magnetic core can be radially slotted, wherein the holding body consists for example of the injector body or the nozzle body.
  • this is made of a material having a high resistivity. Such materials may involve a powder composite, a ferrite material or the like.
  • the measuring device itself comprises a bobbin, which is embedded in the magnetic yoke.
  • the bobbin may comprise either a separate exciter and sensor coil, wherein the bobbin may also be formed at the same time as exciter and sensor coil.
  • the bobbin on electrical connection lines which must be led out of the receiving area of the measuring device, ie from the injector body or from the nozzle body.
  • the sealing of the connecting lines in the body, from which they are led out can be designed in the manner of a glass melting.
  • the glass melting of the electrical connection lines from the magnetic yoke and / or from the injector body and / or from the nozzle body takes place, at the same time a corresponding direction can be achieved.
  • Particularly advantageous is the choice of contact pins, which has the same coefficient of expansion as the melting glass material, such as molybdenum.
  • FIG. 1 shows a section of a non-inventive fuel injector 1 in a cross-sectional view. This extends in an elongated direction about a movement axis 2, so that the lifting movement means are movably received in the movement axis 2.
  • the liftable movement means for generating an opening and closing movement initially comprise a valve piston 7, which is received longitudinally movable within the injector body 12.
  • the valve piston 7 is in operative connection with the likewise received in the movement axis 2 longitudinally movable nozzle needle 9, which is longitudinally movably guided within a nozzle body 13.
  • the nozzle body 13 is arranged adjacent to the injector body 12, wherein all the components forming the movement device, such as the valve piston 7 and the nozzle needle 9, are longitudinally movably guided within the same movement axis 2.
  • all the components forming the movement device such as the valve piston 7 and the nozzle needle 9 are longitudinally movably guided within the same movement axis 2.
  • fuel injection openings 3 introduced within the nozzle body 13 are briefly opened and closed again during a stroke movement. This lifting movement is carried out by all the components forming the moving device.
  • the lifting movement in the valve piston 7 is analogous to the lifting movement of the nozzle needle 9.
  • a measuring device 5 concentrically extends around the valve piston 7.
  • the injector body 12 is shown as being divided in order to indicate an installation possibility of the measuring device 5. This is accommodated within the injector body 12, so that the measuring device 5 executes no lifting movement and with respect to the valve piston 7 assumes a stationary position.
  • the valve piston 7 has a diameter shoulder 8, so that changes due to the different diameter of the valve piston 7, the magnetic circuit in response to the longitudinal position of the valve piston 7 in the direction of the movement axis 2 its inductance.
  • the measuring device 5 consists essentially of a magnetic yoke 6, which is annular and has a U-shaped cross-section.
  • the opening of the U-shape in this case points inwards in the direction of the valve piston 7, wherein the diameter paragraph 8 adjacent to at least one end of the magnetic yoke 6, to cause a maximum change in the inductance.
  • a bobbin 14 is received, which is externally contacted via a connecting line 15. If now the valve piston 7 carries out a lifting movement along the movement axis 2, which is initiated by an electromagnet (not shown), then the nozzle needle 9 opens the fuel injection openings 3, so that fuel is injected into the combustion chamber 4 can be.
  • the lifting movement equally causes a change in location of the diameter paragraph 8 relative to the yoke 6, so that the inductance of the magnetic circuit changes. This change is analyzed by an evaluation unit and gives direct information about the lifting movement of the movement device
  • FIG. 2 schematically a fuel injector 1 according to the invention is shown, which is designed in the manner of a piezoelectrically operated injector.
  • the illustration shows only a partial section of the fuel injector 1 below the intermediate piece 16.
  • a corresponding pressurization or pressure relief of a nozzle needle control chamber 10 takes place, so that the nozzle needle 9 the necessary lifting movement for opening the fuel injection ports 3 for injection of Fuel performs in the combustion chamber 4.
  • the nozzle needle 9 is also received in a fuel injector 1 with a piezoelectric operation within a nozzle body 13, wherein for sealing the nozzle needle control chamber 10, a sealing sleeve 11 is provided.
  • the nozzle sleeve 11 at the same time forms the magnetic yoke 6 of the measuring device 5.
  • the electrical contacting is also carried out according to this embodiment via connecting lines 15, which are led out of the nozzle body 13.
  • the change in the inductance of the magnetic circuit is based on the end face of the nozzle needle 9 adjacent to the nozzle needle control chamber 10, so that the diameter jump can be regarded as a jump to "zero diameter". In any case, the inductance changes during a lifting movement of the nozzle needle 9, so that the measuring device 5 can convert the opening end stop and the closing stop of the nozzle needle 9 into a corresponding electrical signal.
  • the electrical measurement signal which is output by the measuring device 5, is in FIG. 3 shown.
  • the respective abscissa represent the time, in the upper diagram, the ordinate represents the stroke of the valve piston, and the ordinate in the lower diagram outputs the measurement signal.
  • VK the analogous movement of the valve piston and the nozzle needle
  • the ordinate in the upper diagram is marked VK, which describes the valve piston.
  • the ordinate in the lower diagram is denoted by a m, which indicates the measurement signal.
  • the time that passes in the The time course of II to III shows the fully open phase of the valve piston and thus the nozzle needle, which follows from III to IV, the closing phase.
  • I describes the start of opening, II the opening end, III the closing start and IV the closing end.
  • the injection time runs.
  • the measuring signal m between the beginning of opening I and the opening end II shows a signal increase, wherein when reaching the opening end II the signal abruptly drops to zero or by a damped periodic oscillating motion to a zero Signal sets.
  • the time of reaching the opening end II is very accurately detected. Analogous to the detection of the opening end II and the closing end IV can be detected.
  • a change by means of the measuring signal m can be derived from the change in the periodic valve piston and / or nozzle needle movement, the change in the measuring signal m output by means of the measuring device being in the form of a discontinuity, the stroke end stop or closing times periodically following one another by means of the discontinuity and closing cycles are determined.
  • the invention is not limited in its execution to the above-mentioned preferred embodiment. Rather, a number of variants is conceivable, which makes use of the illustrated solution even with fundamentally different types of use.
  • the position of the measuring device 5 is not limited to the arrangements shown.
  • the measuring device 5 can be arranged at any point along the entire movement device, wherein the movement device is not limited only to the valve piston 7 and the nozzle needle 9.

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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)

Abstract

The fuel injector (1) has a displacement device, which carries out opening and closing motion in a movement axis (2). A measuring device (5) is formed as an inductive sensor and the measuring body, partly surrounds a displacement device in the area of a geometry modification formed in movement direction in order to receive an end of the injector in the combustion chamber (4) or the end stop of the opening stroke. An independent claim is also included for a method for detecting an end of injector of fuel into a combustion chamber.

Description

Stand der TechnikState of the art

Die vorliegende Erfindung betrifft einen Kraftstoffinjektor für eine Brennkraftmaschine nach dem Oberbegriff des Anspruchs 1.The present invention relates to a fuel injector for an internal combustion engine according to the preamble of claim 1.

Ein derartiger Kraftstoffinjektor ist beispielsweise durch die DE-A-31 37 761 bekannt geworden.Such a fuel injector is for example by the DE-A-31 37 761 known.

Kraftstoffinjektoren der hier interessierenden Art finden insbesondere Anwendung bei Brennkraftmaschinen, welche derartige Injektoren dafür nutzen, ein dosiertes Einspritzen des zu verbrennenden Kraftstoffs in eine Brennkraftmaschine zu ermöglichen.Fuel injectors of the type of interest here find particular application in internal combustion engines, which use such injectors to allow a metered injection of the fuel to be burned in an internal combustion engine.

Brennkraftmaschinen können mit verschiedenartig ausgebildeten Kraftstoffinjektoren ausgeführt sein, wobei Kraftstoffinjektoren in solche unterschieden werden können, welche als magnetisch betriebene Injektoren bezeichnet werden, und solche, welche als piezoelektrisch betriebene Injektoren zu bezeichnen sind. Magnetisch betriebene Injektoren umfassen einen Elektromagneten, welcher einen Anker bewegen kann, und die über eine Druckstange eine Magnetventilanordnung betätigen. Die Öffnungs- und Schließbewegung der Bewegunnseinrichtung betrifft dabei einen Ventilkolben, dessen Hubbewegung in einer Bewegungsachse auf eine Düsennadel übertragen wird. Die Düsennadel öffnet und schließt den Kraftstofffluss durch kleine Einspritzbohrungen, welche am Düsenkörper des Kraftstoffinjektors angebracht sind und den Kraftstoff in einen Brennraum einspritzen.Internal combustion engines may be embodied with various types of fuel injectors, wherein fuel injectors may be differentiated into those referred to as magnetically operated injectors, and those which may be referred to as piezoelectrically operated injectors. Magnetically operated injectors include an electromagnet which can move an armature and actuate a solenoid valve assembly via a push rod. The opening and closing movement of the Bewegunnseinrichtung relates to a valve piston, the lifting movement is transmitted in a movement axis to a nozzle needle. The nozzle needle opens and closes the fuel flow through small injection bores which are attached to the nozzle body of the fuel injector and inject the fuel into a combustion chamber.

Piezoelektrisch betriebene Injektoren weisen hingegen einen Piezoaktor auf, um über eine nachgeschaltete Ventilanordnung die Öffnungs- und Schließbewegung der Düsennadel auszulösen. Die Bewegungseinrichtung bei piezoelektrisch betriebenen Injektoren kann sich daher auf die Öffnungs- und Schließbewegung der Düsennadel beschränken, wobei die Bewegungseinrichtung durch die dem Piezoaktor nachgeschaltete Ventilanordnung durch eine entsprechende Fluidbeaufschlagung eine Öffnungs- und Schließbewegung ausführt.By contrast, piezoelectrically operated injectors have a piezoelectric actuator in order to trigger the opening and closing movement of the nozzle needle via a downstream valve arrangement. The movement device in the case of piezoelectrically operated injectors can therefore be limited to the opening and closing movement of the nozzle needle, wherein the movement device carries out an opening and closing movement by means of the valve arrangement arranged downstream of the piezoactuator by a corresponding fluid admission.

Aus der Offenlegungsschrift DE 199 37 559 A1 ist ein magnetisch betriebener Injektor bekannt, welcher für ein Einspritzsystem einer Brennkraftmaschine mit einem Magnetventil ausgeführt ist, das den Abfluss von Kraftstoff durch einen Abflusskanal aus einem Ventilsteuerraum steuert, wobei das Magnetventil Mittel zum Verschließen des Abflusskanals, einen von einen Elektromagneten betätigbaren und mit den Mitteln zum Verschließen des Abflusskanals in Wirkverbindung stehenden Anker sowie eine erste Ventilfeder und eine zweite Ventilfeder und einen ersten Hubendanschlag aufweist. Die erste Ventilfeder beaufschlagt den Anker mit einer größeren Federkraft in Schließrichtung, wobei von der Schließstellung des Magnetventils zum Erreichen des ersten Hubendanschlags die zweite Ventilfeder den Anker in Öffnungsrichtung mit einer kleineren Federkraft beaufschlagt. Dabei ist je eine Feder auf jeder Seite des Ankers angeordnet, um den Kraftstoffinjektor kompakt aufzubauen und ein verbessertes Betriebsverhalten bei verschiedenen Frequenzen zu erzielen. Jedoch bietet ein Kraftstoffinjektor der hierin offenbarten Art nicht die Möglichkeit, die Bewegung des Ankers zu messen, um mit den erfassten Messdaten eine mögliche Ansteuerung des Elektromagneten derart positiv zu beeinflussen, dass das Betriebsverhalten insbesondere hinsichtlich der eingespritzten Kraftstoffmenge und des genauen Zeitpunktes der Kraftstoffeinspritzung zu optimieren.From the publication DE 199 37 559 A1 a solenoid operated injector is known, which is designed for an injection system of an internal combustion engine with a solenoid valve, which controls the outflow of fuel through a spillway of a valve control chamber, said solenoid valve means for closing the discharge channel, one of an electromagnet actuated and with the means For closing the drainage channel operatively connected armature and a first valve spring and a second valve spring and a first Hubendanschlag has. The first valve spring acts on the armature with a larger spring force in the closing direction, from the closed position of the solenoid valve to reach the first Hubendanschlags the second valve spring acts on the armature in the opening direction with a smaller spring force. In this case, a respective spring is arranged on each side of the armature in order to build the fuel injector compact and to achieve an improved performance at different frequencies. However, a fuel injector of the type disclosed herein does not offer the ability to measure the movement of the armature to positively influence the possible sensing of the solenoid with the sensed measurement data to optimize performance, particularly with regard to injected fuel quantity and timing of fuel injection ,

In der Offenlegungsschrift DE 10 2004 015 744 A1 ist ein Kraftstoffinjektor nach Art eines piezoelektrisch betriebenen Injektors offenbart. Der Kraftstoffinjektor betrifft insbesondere einen Common- Rail- Injektor zum Einspritzen von Kraftstoff in einen Brennraum einer Brennkraftmaschine. Der Kraftstoffinjektor umfasst ein Injektorgehäuse, das einen Kraftstoffzulauf aufweist, der mit einer zentralen Kraftstoffhochdruckquelle außerhalb des Injektorgehäuses und mit einem Druckraum innerhalb des Injektorgehäuses in Verbindung steht, aus dem in Abhängigkeit von der Stellung eines Steuerventils mit Hochdruck beaufschlagter Kraftstoff eingespritzt wird. Dabei erfolgt eine Hubbewegung einer Düsennadel, welche innerhalb einer Führungsbohrung in einem Düsenkörper geführt ist. Die Düsennadel erreicht im Öffnungszeitpunkt einen Hubendanschlag, und kann ggf. von diesem abprallen bzw. eine Schwingbewegung auslösen. Gleichermaßen kann die Düsennadel auch im Schließzeitpunkt, in dem diese in der Spitze die Spritzlöcher zum Einspritzen des Kraftstoffs in den Brennraum verschließt, ein Schwingverhalten auslösen. Das Schwingverhalten wird immer genau dann eingeleitet, wenn die Düsennadel bzw. die Bewegungseinrichtung des Kraftstoffinjektors den Hubendanschlag bzw. den Schließsitz erreicht. Eine Kontrolle bzw. eine Rückkopplung des Öffnungs- und Schließverhaltens der Düsennadel zur Ansteuerung des Piezoaktors zur Auslösung der Öffnungs- und Schließbewegung der Düsennadel ist nicht möglich. Lediglich ein Ansteuern des Piezoaktors kann verändert werden, wobei eine Rückkopplung der Öffnungs- und Schließbewegung der Düsennadel nicht ausgewertet werden kann.In the published patent application DE 10 2004 015 744 A1 a fuel injector is disclosed in the manner of a piezoelectrically operated injector. In particular, the fuel injector relates to a common rail injector for injecting fuel into a combustion chamber of an internal combustion engine. The fuel injector includes an injector housing having a fuel inlet communicating with a central fuel high pressure source external to the injector housing and with a pressure space within the injector housing from which high pressure fuel is injected in response to the position of a control valve. In this case, a lifting movement of a nozzle needle, which is guided within a guide bore in a nozzle body. The nozzle needle reaches a Hubendanschlag in the opening time, and may possibly rebound from this or trigger a swinging motion. Similarly, the nozzle needle can trigger a vibration behavior even at the closing time, in which it closes the injection holes in the tip for injecting the fuel into the combustion chamber. The vibration behavior is always initiated exactly when the nozzle needle or the Movement device of the fuel injector reaches the Hubendanschlag or the closing seat. A check or a feedback of the opening and closing behavior of the nozzle needle for controlling the piezoelectric actuator to trigger the opening and closing movement of the nozzle needle is not possible. Only a driving of the piezoelectric actuator can be changed, wherein a feedback of the opening and closing movement of the nozzle needle can not be evaluated.

Lediglich zu Forschungs- und Entwicklungszwecken sind Messeinrichtungen zur Erfassung der Bewegung der Bewegungseinrichtungen innerhalb eines Kraftstoffinjektors bekannt, welche jedoch zur genauen Detektion des Zeitpunktes zur Erreichung des Hubendanschlags bzw. des Endanschlags im Schließsitz der Düsennadel bzw. der Bewegungseinrichtung ungeeignet sind. Diese Messeinrichtungen basieren auf einer kapazitiven Abstandsmessung, welche nicht geeignet ist, um größere Hubbewegungen einer Bewegungseinrichtung innerhalb eines Kraftstoffinjektors zu messen.Only for research and development purposes are measuring devices for detecting the movement of the movement devices within a fuel injector known, however, which are unsuitable for accurate detection of the time to reach the Hubendanschlags or the end stop in the closing seat of the nozzle needle or the movement device. These measuring devices are based on a capacitive distance measurement, which is not suitable for measuring larger strokes of a movement device within a fuel injector.

Aus der eingangs genannten DE-A-3137 761 ist eine Kraftstoff-Einspritzdüse mit einer Messeinrichtung für Brennkraftmaschinen mit nach innen öffnender Ventilnadel bekannt, bei welcher im Schließfederraum eine Induktionsspule angeordnet ist, welche zusammen mit einem von der Ventilnadel beeinflussten Anker einen Signalgeber für ein Messgerät zur Ermittlung des Einspritzbeginns und gegebenenfalls weiterer Daten des Einspritzvorganges bildet. Der Luftspalt des magnetischen Kreises der Induktionsspule ist zwischen dem Anker und einem Spulenkern gebildet, gegen den sich der Anker beim Öffnungshub der Ventilnadel bewegt. Dadurch lässt sich ein kleiner Anfangsluftspalt und eine große prozentuale Luftspaltänderung erzielen. Diese Messanordnung eignet sich besonders für Messschaltungen, bei denen an die Induktionsspule eine Gleichspannung gelegt wird und die infolge der Luftspaltänderungen in der Induktionsspule induzierten Spannungen sich der angelegten Gleichspannung überlagern.From the above DE-A-3137761 is a fuel injector with a measuring device for internal combustion engines with inwardly opening valve needle is known, in which the closing spring chamber an induction coil is arranged, which together with an affected by the valve needle anchor a signal generator for a meter for determining the start of injection and possibly further data of the injection process forms. The air gap of the magnetic circuit of the induction coil is formed between the armature and a coil core, against which the armature moves during the opening stroke of the valve needle. As a result, a small initial air gap and a large percentage air gap change can be achieved. This measuring arrangement is particularly suitable for measuring circuits in which a DC voltage is applied to the induction coil and the voltages induced in the induction coil as a result of the air gap changes are superimposed on the applied DC voltage.

Es ist demgegenüber die Aufgabe der vorliegenden Erfindung, bei einem Kraftstoffinjektor der eingangs genannten Art eine andere Ausbildung der Messeinrichtung anzugeben. Diese Aufgabe wird ausgehend von einem Kraftstoffinjektor für eine Brennkraftmaschine gemäß dem Oberbegriff des Anspruchs 1 in Verbindung mit dessen kennzeichnenden Merkmalen gelöst. Vorteilhafte Weiterbildungen der Erfindung sind in den abhängigen Ansprüchen angegeben.It is the object of the present invention to provide a different design of the measuring device in a fuel injector of the type mentioned. This object is achieved on the basis of a fuel injector for an internal combustion engine according to the preamble of claim 1 in conjunction with its characterizing features. Advantageous developments of the invention are specified in the dependent claims.

Erfindungsgemäß ist der Kraftstoffinjektor als piezoelektrisch betriebener Injektor mit einer fluidisch angesteuerten Düsennadel ausgebildet. Folglich muss der Messkörper in Form z. B. eines Magnetjochs in Höhe der Düsennadel angeordnet sein, wobei die Düsennadel in einem Düsenkörper längsbeweglich aufgenommen ist, so dass gemäß einer möglichen Ausführungsform die Messeinrichtung im Düsenkörper selbst eingebaut ist, und das Magnetjoch die Düsennadel oder mit der Düsennadel bewegte Teile umschließt. Piezoelektrisch betriebene Injektoren weisen keinen Ventilkolben auf, der sich durch den Injektor selbst in länglicher Richtung erstreckt. Jedoch ist eine genaue Messung des Hubes der Düsennadel an bzw. mit der Düsennadel selbst mit der Messeinrichtung möglich. Die Düsennadel grenzt an einen Düsennadelsteuerraum endseitig an, welcher mit einer Dichthülse abgedichtet ist, wobei die Messeinrichtung durch die Dichthülse und die in Bewegungsrichtung der Düsennadel ausgebildete Geometrieänderung durch das an den Düsennadelsteuerraum angrenzende Ende der Düsennadel gebildet ist. Somit kann die Messeinrichtung und die Dichthülse zur Abdichtung des Düsennadelsteuerraums als einziges Konstruktionsbauteil ausgeführt sein. Als quasi - Durchmessersprung dient die Stirnseite der Düsennadel selbst, d.h. es erfolgt ein "Durchmessersprung auf Null".According to the invention, the fuel injector is designed as a piezoelectrically operated injector with a fluidically actuated nozzle needle. Consequently, the measuring body in the form of z. B. a magnetic yoke in height of the nozzle needle, wherein the nozzle needle is received longitudinally movably in a nozzle body, so that according to a possible embodiment, the measuring device is installed in the nozzle body itself, and the magnetic yoke surrounds the nozzle needle or with the nozzle needle moving parts. Piezo-electrically driven injectors do not have a valve piston which extends through the injector itself in an elongated direction. However, an accurate measurement of the stroke of the nozzle needle on or with the nozzle needle itself with the measuring device is possible. The nozzle needle adjoins a nozzle needle control chamber at the end, which is sealed with a sealing sleeve, wherein the measuring device is formed by the sealing sleeve and the change in geometry formed in the direction of movement of the nozzle needle by the needle adjacent to the nozzle needle control chamber end of the nozzle needle. Thus, the measuring device and the sealing sleeve can be designed to seal the nozzle needle control chamber as the only structural component. As a quasi - diameter jump serves the end face of the nozzle needle itself, i. There is a "diameter jump to zero".

Um die Messeinrichtung ortsfest anzuordnen, wird diese entweder in dem Injektorkörper oder im Düsenkörper eingebaut. Der Injektorkörper und der Düsenkörper bilden jeweils den haltekörperfesten Teil des Injektors, wobei der Injektorkörper und der Düsenkörper selbst als magnetisches Material die Induktivität der Messeinrichtung beeinflussen. Zur Vermeidung von Wirbelströmen an den haltekörperfesten Teilen kann der das Feld führende haltekörperfeste Magnetkern radial geschlitzt sein, wobei der Haltekörper beispielsweise aus dem Injektorkörper oder dem Düsenkörper besteht. Alternativ besteht die Möglichkeit, dass dieser aus einem Material mit einem hohen spezifischen Widerstand ausgeführt ist. Derartige Materialien können ein Pulververbundmaterial, ein Ferritmaterial oder dergleichen betreffen. Die Messeinrichtung selbst umfasst einen Spulenkörper, welcher im Magnetjoch eingebettet ist. Der Spulenkörper kann entweder eine voneinander getrennte Erreger- und Sensorspule umfassen, wobei der Spulenkörper auch zugleich als Erreger- und Sensorspule ausgebildet sein kann.In order to arrange the measuring device stationary, this is installed either in the injector body or in the nozzle body. The injector body and the nozzle body respectively form the holder body fixed part of the injector, wherein the injector body and the nozzle body itself influence the inductance of the measuring device as a magnetic material. In order to avoid eddy currents on the holder-fixed parts, the field-leading holding body-fixed magnetic core can be radially slotted, wherein the holding body consists for example of the injector body or the nozzle body. Alternatively, it is possible that this is made of a material having a high resistivity. Such materials may involve a powder composite, a ferrite material or the like. The measuring device itself comprises a bobbin, which is embedded in the magnetic yoke. The bobbin may comprise either a separate exciter and sensor coil, wherein the bobbin may also be formed at the same time as exciter and sensor coil.

Gemäß einer weiteren Ausführungsform der Erfindung weist der Spulenkörper elektrische Anschlussleitungen auf, welche aus dem Aufnahmebereich der Messeinrichtung, also aus dem Injektorkörper oder aus dem Düsenkörper, herausgeführt werden müssen. Die Versiegelung der Anschlussleitungen in dem Körper, aus dem diese herausgeführt werden, kann nach Art einer Glaseinschmelzung ausgebildet sein. Somit findet die Glaseinschmelzung der elektrischen Anschlussleitungen aus dem Magnetjoch und/oder aus dem Injektorkörper und/oder aus dem Düsenkörper statt, wobei zugleich eine entsprechende Richtung erzielbar ist. Besonders vorteilhaft ist die Wahl von Kontaktstiften, die den gleichen Ausdehnungskoeffizienten wie das einschmelzende Glasmaterial hat, beispielsweise Molybdän.According to a further embodiment of the invention, the bobbin on electrical connection lines, which must be led out of the receiving area of the measuring device, ie from the injector body or from the nozzle body. The sealing of the connecting lines in the body, from which they are led out, can be designed in the manner of a glass melting. Thus, the glass melting of the electrical connection lines from the magnetic yoke and / or from the injector body and / or from the nozzle body takes place, at the same time a corresponding direction can be achieved. Particularly advantageous is the choice of contact pins, which has the same coefficient of expansion as the melting glass material, such as molybdenum.

Weitere, die Erfindung verbessernde Maßnahmen werden nachstehend gemeinsam mit der Beschreibung bevorzugter Ausführungsbeispiele der Erfindung anhand von Figuren näher dargestellt.Further, measures improving the invention will be described in more detail below together with the description of preferred embodiments of the invention with reference to figures.

Zeichnungdrawing

Es zeigt:

Figur 1
eine Ansicht eines nicht erfindungsgemäßen Kraftstoffinjektors in einem Querschnitt, wobei der Kraftstoffinjektor als magnetisch betriebener Injektor ausgebildet ist, und die Messeinrichtung einen Ventilkolben innerhalb des Kraftstoffinjektors umschließt;
Figur 2
eine schematisierte Ansicht eines erfindungsgemäßen piezoelektrisch betriebenen Kraftstoffinjektors, wobei die Messeinrichtung einteilig mit der Dichthülse ausgeführt ist, welche einen endseitig an der Düsennadel angrenzenden Düsennadelsteuerraum abdichtet;
Figur 3
in einem Diagramm einen Verlauf einer Öffnungs- und Schließbewegung einer Düsennadel und ein zugehöriges Messsignal, welches durch die erfindungsgemäße Messeinrichtung ausgegeben wird.
It shows:
FIG. 1
a view of a non-inventive fuel injector in a cross section, wherein the fuel injector is designed as a magnetically operated injector, and the measuring device encloses a valve piston within the fuel injector;
FIG. 2
a schematic view of a piezoelectric fuel injector according to the invention, wherein the measuring device is designed in one piece with the sealing sleeve, which seals a end adjacent to the nozzle needle nozzle needle control chamber;
FIG. 3
in a diagram, a profile of an opening and closing movement of a nozzle needle and an associated measurement signal, which is output by the measuring device according to the invention.

Die Figur 1 zeigt einen Ausschnitt eines nicht erfindungsgemäßen Kraftstoffinjektors 1 in einer quergeschnittenen Darstellung. Dieser erstreckt sich in länglicher Richtung um eine Bewegungsachse 2, so dass die hubbeweglichen Bewegungseinrichtungen in der Bewegungsachse 2 bewegbar aufgenommen sind. Die hubbeweglichen Bewegungseinrichtungen zur Erzeugung einer Öffnungs- und Schließbewegung umfassen zunächst einen Ventilkolben 7, welcher längsbeweglich innerhalb des Injektorkörpers 12 aufgenommen ist. Der Ventilkolben 7 steht in Wirkverbindung mit der ebenfalls in der Bewegungsachse 2 längsbeweglich aufgenommenen Düsennadel 9, welche längsbeweglich innerhalb eines Düsenkörpers 13 geführt ist. Der Düsenkörper 13 ist angrenzend an den Injektorkörper 12 angeordnet, wobei sämtliche die Bewegungseinrichtung bildenden Komponenten wie der Ventilkolben 7 und die Düsennadel 9 innerhalb der gleichen Bewegungsachse 2 längsbeweglich geführt sind. Bei einer Hubbewegung der Düsennadel 9 werden innerhalb des Düsenkörpers 13 eingebrachte Kraftstoffeinspritzöffnungen 3 bei einer Hubbewegung kurzzeitig geöffnet und wieder verschlossen. Diese Hubbewegung wird von allen die Bewegungseinrichtung bildenden Komponenten ausgeführt. So ist etwa die Hubbewegung im Ventilkolben 7 analog zur Hubbewegung der Düsennadel 9.The FIG. 1 shows a section of a non-inventive fuel injector 1 in a cross-sectional view. This extends in an elongated direction about a movement axis 2, so that the lifting movement means are movably received in the movement axis 2. The liftable movement means for generating an opening and closing movement initially comprise a valve piston 7, which is received longitudinally movable within the injector body 12. The valve piston 7 is in operative connection with the likewise received in the movement axis 2 longitudinally movable nozzle needle 9, which is longitudinally movably guided within a nozzle body 13. The nozzle body 13 is arranged adjacent to the injector body 12, wherein all the components forming the movement device, such as the valve piston 7 and the nozzle needle 9, are longitudinally movably guided within the same movement axis 2. During a lifting movement of the nozzle needle 9, fuel injection openings 3 introduced within the nozzle body 13 are briefly opened and closed again during a stroke movement. This lifting movement is carried out by all the components forming the moving device. For example, the lifting movement in the valve piston 7 is analogous to the lifting movement of the nozzle needle 9.

Konzentrisch um den Ventilkolben 7 erstreckt sich eine Messeinrichtung 5. Beispielhaft ist der Injektorkörper 12 geteilt dargestellt, um eine Montagemöglichkeit der Messeinrichtung 5 anzudeuten. Diese ist innerhalb des Injektorkörpers 12 aufgenommen, so dass die Messeinrichtung 5 keine Hubbewegung ausführt und gegenüber dem Ventilkolben 7 eine ruhende Position einnimmt. In der Höhe der Messeinrichtung 5 weist der Ventilkolben 7 einen Durchmesserabsatz 8 auf, so dass aufgrund der verschiedenen Durchmesser des Ventilkolbens 7 der Magnetkreis in Abhängigkeit von der Längsposition des Ventilkolbens 7 in Richtung der Bewegungsachse 2 seine Induktivität ändert. Die Messeinrichtung 5 besteht im Wesentlichen aus einem Magnetjoch 6, welches ringförmig ausgebildet ist und einen U-förmigen Querschnitt aufweist. Die Öffnung der U-Form weist dabei nach innen in Richtung des Ventilkolbens 7, wobei der Durchmesserabsatz 8 an zumindest einen Ende des Magnetjochs 6 angrenzt, um eine maximale Änderung der Induktivität hervorzurufen. Innerhalb des Magnetjochs 6 ist ein Spulenkörper 14 aufgenommen, welcher über eine Anschlussleitung 15 extern kontaktierbar ist. Führt nunmehr der Ventilkolben 7 eine Hubbewegung entlang der Bewegungsachse 2 aus, welche durch einen - nicht näher dargestellten - Elektromagneten eingeleitet wird, so öffnet die Düsennadel 9 die Kraftstoffeinspritzöffnungen 3, so dass Kraftstoff in den Brennraum 4 eingespritzt werden kann. Die Hubbewegung bewirkt gleichermaßen eine Ortsänderung des Durchmesserabsatzes 8 relativ zum Magnetjoch 6, so dass sich die Induktivität des Magnetkreises ändert. Diese Änderung wird über eine Auswerteeinheit analysiert und gibt eine direkte Information über die Hubbewegung der BewegungseinrichtungA measuring device 5 concentrically extends around the valve piston 7. The injector body 12 is shown as being divided in order to indicate an installation possibility of the measuring device 5. This is accommodated within the injector body 12, so that the measuring device 5 executes no lifting movement and with respect to the valve piston 7 assumes a stationary position. In the height of the measuring device 5, the valve piston 7 has a diameter shoulder 8, so that changes due to the different diameter of the valve piston 7, the magnetic circuit in response to the longitudinal position of the valve piston 7 in the direction of the movement axis 2 its inductance. The measuring device 5 consists essentially of a magnetic yoke 6, which is annular and has a U-shaped cross-section. The opening of the U-shape in this case points inwards in the direction of the valve piston 7, wherein the diameter paragraph 8 adjacent to at least one end of the magnetic yoke 6, to cause a maximum change in the inductance. Within the magnetic yoke 6, a bobbin 14 is received, which is externally contacted via a connecting line 15. If now the valve piston 7 carries out a lifting movement along the movement axis 2, which is initiated by an electromagnet (not shown), then the nozzle needle 9 opens the fuel injection openings 3, so that fuel is injected into the combustion chamber 4 can be. The lifting movement equally causes a change in location of the diameter paragraph 8 relative to the yoke 6, so that the inductance of the magnetic circuit changes. This change is analyzed by an evaluation unit and gives direct information about the lifting movement of the movement device

In Figur 2 ist schematisch ein erfindungsgemäßen Kraftstoffinjektor 1 gezeigt, welcher nach Art eines piezoelektrisch betriebenen Injektors ausgeführt ist. Die Darstellung zeigt lediglich einen Teilschnitt des Kraftstoffinjektors 1 unterhalb des Zwischenstückes 16. Über die Verbindungskanäle 17, 18 und 19 findet eine entsprechende Druckbeaufschlagung bzw. Druckentlastung eines Düsennadelsteuerraums 10 statt, so dass die Düsennadel 9 die erforderliche Hubbewegung zur Öffnung der Kraftstoffeinspritzöffnungen 3 zur Einspritzung des Kraftstoffs in den Brennraum 4 ausführt. Die Düsennadel 9 ist auch bei einem Kraftstoffinjektor 1 mit einem piezoelektrischen Betrieb innerhalb eines Düsenkörpers 13 aufgenommen, wobei zur Abdichtung des Düsennadelsteuerraums 10 eine Dichthülse 11 vorgesehen ist. Gemäß der vorliegenden Erfindung bildet die Düsenhülse 11 zugleich das Magnetjoch 6 der Messeinrichtung 5. Dargestellt ist die Dichthülse 11 in einer Ringform, welche außenseitig den Spulenkörper 14 aufnimmt. Die elektrische Kontaktierung erfolgt auch gemäß dieses Ausführungsbeispiels über Anschlussleitungen 15, welche aus dem Düsenkörper 13 herausgeführt sind. Die Änderung der Induktivität des Magnetkreises basiert auf der Endfläche der Düsennadel 9 angrenzend an den Düsennadelsteuerraum 10, so dass der Durchmessersprung als ein Sprung auf "Durchmesser Null" betrachtet werden kann. Jedenfalls ändert sich die Induktivität bei einer Hubbewegung der Düsennadel 9, so dass die Messeinrichtung 5 den Öffnungsendanschlag sowie den Schließanschlag der Düsennadel 9 in ein entsprechendes elektrisches Signal umwandeln kann.In FIG. 2 schematically a fuel injector 1 according to the invention is shown, which is designed in the manner of a piezoelectrically operated injector. The illustration shows only a partial section of the fuel injector 1 below the intermediate piece 16. Via the connecting channels 17, 18 and 19, a corresponding pressurization or pressure relief of a nozzle needle control chamber 10 takes place, so that the nozzle needle 9 the necessary lifting movement for opening the fuel injection ports 3 for injection of Fuel performs in the combustion chamber 4. The nozzle needle 9 is also received in a fuel injector 1 with a piezoelectric operation within a nozzle body 13, wherein for sealing the nozzle needle control chamber 10, a sealing sleeve 11 is provided. According to the present invention, the nozzle sleeve 11 at the same time forms the magnetic yoke 6 of the measuring device 5. Shown is the sealing sleeve 11 in a ring shape, which receives the coil body 14 on the outside. The electrical contacting is also carried out according to this embodiment via connecting lines 15, which are led out of the nozzle body 13. The change in the inductance of the magnetic circuit is based on the end face of the nozzle needle 9 adjacent to the nozzle needle control chamber 10, so that the diameter jump can be regarded as a jump to "zero diameter". In any case, the inductance changes during a lifting movement of the nozzle needle 9, so that the measuring device 5 can convert the opening end stop and the closing stop of the nozzle needle 9 into a corresponding electrical signal.

Das elektrische Messsignal, welches durch die Messeinrichtung 5 ausgegeben wird, ist in Figur 3 dargestellt. Die jeweiligen Abszissen stellen die Zeit dar, wobei im oberen Diagramm die Ordinate den Hub des Ventilkolbens darstellt, und die Ordinate im unteren Diagramm das Messsignal ausgibt. Mit der analogen Bewegung des Ventilkolbens und der Düsennadel ist die Ordinate im oberen Diagramm mit VK gekennzeichnet, was den Ventilkolben beschreibt. Die Ordinate im unteren Diagramm ist mit einem m bezeichnet, welches das Messsignal andeutet. Öffnet der Kraftstoffinjektor durch eine Hubbewegung des Ventilkolbens, so verläuft die Kurve, welche im oberen Diagramm die Bewegung des Ventilkolbens darstellt, von der Position I zur Position II. Die Zeit, welche vergeht, in der sich der Ventilkolben von I bis II bewegt, stellt die Öffnungsphase dar. Der Zeitverlauf von II bis III zeigt die vollständig geöffnete Phase des Ventilkolbens und damit der Düsennadel, wonach von III bis IV die Schließphase folgt. Damit beschreibt I den Öffnungsbeginn, II das Öffnungsende, III den Schließbeginn und IV das Schließende. Zwischen dem Öffnungsbeginn I und dem Schließende IV verläuft die Einspritzzeit. Gemäß dem Verlauf der Öffnungs- und Schließbewegung des Ventilkolbens VK zeigt das Messsignal m zwischen dem Öffnungsbeginn I und dem Öffnungsende II einen Signalanstieg, wobei bei Erreichen des Öffnungsendes II das Signal schlagartig auf Null abfällt bzw. sich durch eine gedämpfte periodische Schwingbewegung auf ein Null-Signal einstellt. Damit ist der Zeitpunkt des Erreichens des Öffnungsendes II sehr exakt detektierbar. Analog zur Detektion des Öffnungsendes II kann auch das Schließende IV detektiert werden. Aus der Änderung der periodischen Ventilkolben- und/oder Düsennadelbewegung ist eine Änderung mittels des Messsignals m ableitbar, wobei sich die Änderung des mittels der Messeinrichtung ausgegebenen Messsignals m in Form einer Unstetigkeit ergibt, wobei mittels der Unstetigkeit die Hubendanschlags- oder Schließzeitpunkte periodisch aufeinander folgender Öffnungs- und Schließzyklen ermittelt werden.The electrical measurement signal, which is output by the measuring device 5, is in FIG. 3 shown. The respective abscissa represent the time, in the upper diagram, the ordinate represents the stroke of the valve piston, and the ordinate in the lower diagram outputs the measurement signal. With the analogous movement of the valve piston and the nozzle needle, the ordinate in the upper diagram is marked VK, which describes the valve piston. The ordinate in the lower diagram is denoted by a m, which indicates the measurement signal. Opens the fuel injector by a lifting movement of the valve piston, the curve, which represents the movement of the valve piston in the upper diagram, from the position I to position II. The time that passes in the The time course of II to III shows the fully open phase of the valve piston and thus the nozzle needle, which follows from III to IV, the closing phase. Thus, I describes the start of opening, II the opening end, III the closing start and IV the closing end. Between the beginning of the opening I and the closing end IV, the injection time runs. According to the course of the opening and closing movement of the valve piston VK, the measuring signal m between the beginning of opening I and the opening end II shows a signal increase, wherein when reaching the opening end II the signal abruptly drops to zero or by a damped periodic oscillating motion to a zero Signal sets. Thus, the time of reaching the opening end II is very accurately detected. Analogous to the detection of the opening end II and the closing end IV can be detected. A change by means of the measuring signal m can be derived from the change in the periodic valve piston and / or nozzle needle movement, the change in the measuring signal m output by means of the measuring device being in the form of a discontinuity, the stroke end stop or closing times periodically following one another by means of the discontinuity and closing cycles are determined.

Die Erfindung beschränkt sich in ihrer Ausführung nicht auf das vorstehend angegebene bevorzugte Ausführungsbeispiel. Vielmehr ist eine Anzahl von Varianten denkbar, welche von der dargestellten Lösung auch bei grundsätzlich anders gearteten Ausführungen Gebrauch macht. Insbesondere sei angemerkt, dass die Position der Messeinrichtung 5 nicht auf die dargestellten Anordnungen begrenzt ist. Die Messeinrichtung 5 kann an einer beliebigen Stelle entlang der gesamten Bewegungsseinrichtung angeordnet werden, wobei die Bewegungseinrichtung nicht lediglich auf den Ventilkolben 7 sowie die Düsennadel 9 begrenzt ist.The invention is not limited in its execution to the above-mentioned preferred embodiment. Rather, a number of variants is conceivable, which makes use of the illustrated solution even with fundamentally different types of use. In particular, it should be noted that the position of the measuring device 5 is not limited to the arrangements shown. The measuring device 5 can be arranged at any point along the entire movement device, wherein the movement device is not limited only to the valve piston 7 and the nozzle needle 9.

Claims (4)

  1. Fuel injector (1) for an internal combustion engine, with a nozzle needle (9) which executes an opening and closing movement in a movement axis (2) for opening and closing at least one fuel injection port (3) for the injection of fuel into a combustion space (4), the fuel injector (1) having a measuring device (5) which is designed as an inductive sensor and comprises a measuring body which at least partially surrounds the nozzle needle (9) in the region of a geometry change formed in the direction of movement, in order to detect the end of injection into the combustion space and/or the limit stop of the opening stroke, characterized in that the fuel injector (1) is designed as a piezoelectrically operated injector with a fluidically activated nozzle needle (9), and in that the nozzle needle (9) is contiguous on the end face to a nozzle-needle control space (10) which is sealed off by means of a sealing sleeve (11), the measuring device (5) being formed by the sealing sleeve (11), and the geometry change formed in the direction of movement of the nozzle needle (9) being formed by that end of the nozzle needle (9) which is contiguous to the nozzle-needle control space (10).
  2. Fuel injector according to Claim 1, characterized in that the fuel injector (1) comprises an injector body (12) and a nozzle body (13) arranged on the latter, and the measuring device (5) is received in the injector body (12) and/or in the nozzle, body (13).
  3. Fuel injector according to Claim 1 or 2,
    characterized in that the measuring device (5) comprises a coil body (14) which is embedded in a magnet yoke (6) and which is designed as an exciting and sensor coil, the magnet yoke (6) being slotted radially and/or having a material with high specific resistance comprising a composite powder material and/or a ferrite material.
  4. Fuel injector according to Claim 3, characterized in that the coil body (14) has electrical connecting lines (15) which, in the manner of a melting of glass, are led out of the magnet yoke (6) and/or out of the injector body (12) and/or out of the nozzle body (13) and sealed off.
EP07115363A 2006-10-30 2007-08-31 Fuel injector with a measuring device Not-in-force EP1925813B1 (en)

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DE102006051205A DE102006051205A1 (en) 2006-10-30 2006-10-30 Fuel injector for internal combustion engine, has measuring device, which is formed as inductive sensor and measuring body, partly surrounds displacement device

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EP1925813A1 EP1925813A1 (en) 2008-05-28
EP1925813B1 true EP1925813B1 (en) 2009-11-18

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DE3137761A1 (en) 1981-09-23 1983-03-31 Robert Bosch Gmbh, 7000 Stuttgart FUEL INJECTION NOZZLE FOR INTERNAL COMBUSTION ENGINES
DE3937750A1 (en) * 1989-11-14 1991-05-16 Bosch Gmbh Robert FUEL INJECTION NOZZLE FOR INTERNAL COMBUSTION ENGINES
DE4142996A1 (en) * 1991-12-24 1993-07-01 Bosch Gmbh Robert METHOD FOR MEASURING THE MECHANICAL MOVEMENT OF A SOLENOID VALVE ARMOR, ESPECIALLY ELECTRICALLY CONTROLLED INJECTION SYSTEMS
DE4325904C2 (en) * 1993-08-02 1995-07-20 Daimler Benz Ag Fuel injection system provided for a diesel internal combustion engine with a high-pressure pump delivering the fuel into a common supply line (common rail) for all injection nozzles
GB2340610A (en) * 1998-08-18 2000-02-23 Lucas Ind Plc Needle lift sensor
DE102004015744A1 (en) 2004-03-31 2005-10-13 Robert Bosch Gmbh Common rail injector

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2014060799A1 (en) 2012-10-19 2014-04-24 Politecnico Di Bari Optical system for the measurement of the displacement of a movable body drowned in a fluid

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DE502007002021D1 (en) 2009-12-31
ATE449252T1 (en) 2009-12-15
EP1925813A1 (en) 2008-05-28

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