EP0099991B1 - Fuel injector for an internal-combustion engine - Google Patents

Fuel injector for an internal-combustion engine Download PDF

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Publication number
EP0099991B1
EP0099991B1 EP83106279A EP83106279A EP0099991B1 EP 0099991 B1 EP0099991 B1 EP 0099991B1 EP 83106279 A EP83106279 A EP 83106279A EP 83106279 A EP83106279 A EP 83106279A EP 0099991 B1 EP0099991 B1 EP 0099991B1
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EP
European Patent Office
Prior art keywords
coil
coil core
armature
bore
injection nozzle
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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.)
Expired
Application number
EP83106279A
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German (de)
French (fr)
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EP0099991A1 (en
Inventor
Bernhard Kaczynski
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Robert Bosch GmbH
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Robert Bosch GmbH
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Publication of EP0099991A1 publication Critical patent/EP0099991A1/en
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • 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

Definitions

  • the invention is based on a fuel injection nozzle for internal combustion engines according to the preamble of claim 1.
  • These injection nozzles are characterized in that only one induction coil is required for the signal and that relatively large percentage changes in the air gap or the pole faces delimiting the air gap can be achieved so that only a relatively small amount of effort is required for signal amplification in the measuring circuit.
  • a converter which consists of a stationary part which generates a magnetic field and a second part which is moved by the valve needle.
  • the magnetic field-producing part of the transducer is designed as a screw which is screwed into a threaded bore extending from the rear end of the nozzle holder and can be adjusted as a whole in the threaded bore for the purpose of axial adjustment relative to the second part of the transducer.
  • This version requires a special design of the nozzle holder, in which the fuel supply line is not inserted centrally into the nozzle holder, as is usual, but laterally.
  • the arrangement according to the invention with the characterizing features of claim 1 has the advantage that the coil core for adjusting the initial air gap or the initial size of the opposing pole faces on the coil core and armature can still be adjusted axially even after the injection nozzle has been assembled, without that for the Nozzle holder must be provided for a special design that deviates from the usual design with a central introduction of the fuel supply line.
  • the initial air gap or the initial size of the pole faces can be determined, for example, by electronic measurement of the initial inductance of the induction coil, or mechanically by the distance between the relevant surfaces on the armature and the coil core relative to a reference plane, for example the separation plane between the nozzle holder, before the injection nozzle is assembled and between the disc or nozzle body.
  • the adjusting element which determines the axial position of the coil core can be readjusted in accordance with the actually desired initial value of the air gap or pole face size and then the coil core can be fixed in the set position, e.g. B. be clamped by caulking.
  • the bore for receiving the adjusting member opens at an acute angle into the bore receiving the coil core or the bobbin.
  • the adjusting element can be a bolt which is inserted into the bore permanently or only temporarily during adjustment.
  • the coil core be displaceably guided in an extension of the coil body and provided on the side facing away from the armature with a pin which fits into a narrowed bore section in the nozzle holder.
  • the armature influenced by the valve needle or a rod part connecting the armature to the valve needle can be made particularly short if the coil core passes axially through the induction coil and is displaceably guided therein.
  • the arrangement can also be such that both the coil core and the armature are immersed in the induction coil and the magnetic air gap is arranged between these parts within the induction coil.
  • the bores in the nozzle holder which serve to receive the induction coil and the coil core can be sealed in a simple manner against leakage oil leakage in that the coil body and / or the coil core carries a sealing ring on the outer circumference.
  • FIG. 1 shows the first exemplary embodiment partly in longitudinal section and partly in side view
  • FIG. 2 shows a partial longitudinal section through the second exemplary embodiment that is enlarged compared to FIG.
  • the injection nozzle according to FIG. 1 has a nozzle holder 10, against which an intermediate plate 11 and a nozzle body 12 are clamped by a union nut 13.
  • a valve needle 14 is displaceably mounted in the nozzle body 12, on which a closing spring 16 acts via a pressure piece 15 and is accommodated in a spring chamber 17 of the nozzle holder 10.
  • the valve needle 14 cooperates with an inward-facing valve seat in the nozzle body 12 and executes its opening stroke against the direction of flow of the fuel.
  • the guide bore of the valve needle 14 is, as usual, expanded at one point to a pressure chamber, in the area of which the valve needle 14 has a pressure shoulder facing the valve seat and which has channels 18, 19, 20 and 21 in the intermediate disk 11 or the nozzle holder 10 Fuel connection nozzle 22 of the nozzle holder 10 is connected.
  • the fuel pressure acting on the pressure shoulder of the valve needle 14 pushes the valve needle 14 upward against the force of the closing spring 16 until an invisible shoulder on the valve needle 14 abuts against the lower end face of the intermediate disk 11 and limits the further upward stroke of the valve needle 14.
  • the closing spring 16 is supported by a washer 24 on a flange part 25 made of magnetically conductive material, which abuts a shoulder 26 of the nozzle housing 10, which is formed at the transition from the spring chamber 17 to a multi-step blind bore 28.
  • An induction coil designated as a whole with the reference number 30 is inserted into the latter, the winding 31 of which is applied to a coil body 32.
  • Flange part 25 and coil body 32 are firmly connected to one another by means of a suitable method (glued, overmoulded).
  • an anchor bolt 34 made of magnetically conductive material is slidably guided, which is firmly connected to the pressure piece 15 via an extension 35 and thereby moves with the valve needle 14 in both directions.
  • the extension 35 is advantageously designed as a plastic part which is firmly connected to the anchor bolt 34 and the pressure piece 15 by a suitable method. This design of the extension 35 ensures that the anchor bolt 34 can move without jamming in the flange part 25 and the coil body 32.
  • the coil former 32 is provided on the end face facing away from the flange part 25 with a hub-shaped extension 38, in which a coil core 40, which cooperates with the anchor bolt 34 and is made of magnetically conductive material, is slidably mounted.
  • This has a blind bore 41 in its front end facing the anchor bolt 34, the diameter of which is larger than the diameter of the anchor bolt 34 by twice the residual air gap between the anchor bolt 34 and the coil former 40.
  • the coil core 40 is provided with a pin 42, which fits into the stepped inner section 43 of the blind bore 28 with a metallic contact.
  • the end face of the pin 42 rests on the front end of a stud screw 44 which is screwed into a threaded bore 45 which extends at an acute angle a to the longitudinal axis of the injection nozzle.
  • a lateral recess 48 is provided in the nozzle holder 10, which cuts the bore 28 in the region of its central section 49 receiving the attachment 38.
  • Means 50 are provided in the recess 48 for sealingly leading out the winding ends of the induction coil 30 and connecting them to a further cable 51, via which an evaluation circuit can be connected to the injection nozzle.
  • a sealing ring 52 is also provided on the circumference of the coil former 32 and a sealing ring 53 on the circumference of the coil core 40.
  • a longitudinal bore 54 and a transverse bore 55 are provided in the anchor bolt 34 to relieve the pressure in the blind bore 41 against the spring chamber 17.
  • the magnetic field of the induction coil 30 leads via the armature bolt 34, the flange part 25, the inner region of the nozzle holder 10, the coil core 40 and the air gap which is formed between the coil core 40 and the armature bolt 34.
  • the arrangement is such that even when the valve is closed, the anchor bolt 34 dips a very small amount into the blind bore 41.
  • the smallest air gap between the armature bolt 34 and the coil core 40, which results from the radial play between these parts, is already present in the starting position.
  • the signal-generating change in the magnetic field resistance is caused by the fact that during the opening stroke of the valve needle 14 the anchor bolt 34 dips deeper into the blind bore 41 and the pole faces of the parts delimiting the air gap thereby increase.
  • the initial size of the pole faces when the valve is closed can be set to any desired value by means of the stud screw 44.
  • the value set in each case can be determined, for example, by detecting the inductance of the coil by means of an electronic circuit. However, adjustment by purely mechanical measurement is also possible.
  • the distance of the free end face of the anchor bolt 34 from the upper end face of the washer 11, such as the distance of the free end face of the coil core 40 from the lower end face of the nozzle holder 10 is determined. The desired difference between the two distances can then be easily adjusted by appropriately turning the stud screw 44.
  • the coil core 40 is fixed at a point 58 in the nozzle holder 10 by caulking by means of a tool inserted into the recess 48.
  • the arrangement according to the invention is not restricted to the construction shown and described.
  • the air gap could, for example, also be formed between plane pole faces oriented perpendicular to the longitudinal axis of the injection nozzle, the signal being generated solely by changing the length of the air gap.
  • An arrangement is particularly advantageous in which, when the valve needle 14 is in the closed position, the anchor bolt 34 is not yet immersed in the blind bore 41, because particularly large changes in the magnetic resistance can be achieved via the valve needle stroke.
  • the adjustability of the coil core according to the invention is also not limited to the fact that the coil core is arranged on the side of the winding of the induction coil remote from the valve needle 14 and the armature bolt passes through the coil body.
  • the arrangement is such that a coil core 60 is passed through the winding 61 of an induction coil, designated as a whole by the reference number 62, and has a thickened end face 63 protruding from the winding 61, in which the end cooperating with the armature bolt 34 Blind bore 41 is arranged.
  • the anchor bolt 34 is here much shorter than in the embodiment according to FIG. 1 and, moreover, tapered at its free end, so that both air gap reductions and increases in the pole area result in the valve needle lifts.
  • a flange part 65 consisting of magnetically conductive material is also provided here, which abuts the end face 63 of the coil core 60 via a magnetically insulating molded part 66 and connects it with this z. B. is connected by adhesive.
  • the molded part 66 is also used to guide the anchor bolt 34.
  • a sealing ring 67 is stretched between the nozzle holder and the front end 63 of the coil core 60.
  • the coil core 60 is fixed in the nozzle holder by caulking.
  • the blind bore 41 could also be formed in the armature bolt 34 instead of in the coil core 60, which would be provided with a thickened head part for this purpose.
  • both the coil core and the anchor bolt are immersed in the induction coil, the magnetic air gap being formed within the induction coil.

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

Description

Stand der TechnikState of the art

Die Erfindung geht aus von einer Kraftstoff-Einspritzdüse für Brennkraftmaschinen nach der Gattung der Patentanspruches 1. Diese Einspritzdüsen zeichnen sich dadurch aus, daß für die Signaigabe nur eine Induktionspule benötigt wird und daß sich relativ große prozentuale Änderungen des Luftspaltes bzw. der den Luftspalt begrenzenden Polflächen erzielen lassen, so daß für die Signalverstärkung in der Meßschaltung nur ein verhältnismäßig geringer Aufwand notwendig ist.The invention is based on a fuel injection nozzle for internal combustion engines according to the preamble of claim 1. These injection nozzles are characterized in that only one induction coil is required for the signal and that relatively large percentage changes in the air gap or the pole faces delimiting the air gap can be achieved so that only a relatively small amount of effort is required for signal amplification in the measuring circuit.

Bei bekannten Einspritzdüsen mit einem induktiven Signalgeber (FR-A-2320557) ist ein Wandler vorgesehen, welcher aus einem ein Magnetfeld erzeugenden ruhenden Teil und einem mit der Ventilnadel bewegten zweiten Teil besteht. Der magnetfelderzeugende Teil des Wandlers ist als Schraubstück ausgebildet, welches in eine vom rückseitigen Stirnende des Düsenhalters ausgehende Gewindebohrung eingeschraubt ist und zum Zweck der axialen Einstellung gegenüber dem zweiten Teil des Wandlers als Ganzes in der Gewindebohrung verstellt werden kann. Diese Ausführung bedingt eine Sonderbauform des Düsenhalters, bei welcher die Kraftstoff-Zuleitung nicht wie üblich zentral, sondern seitlich in den Düsenhalter eingeführt ist.In known injection nozzles with an inductive signal transmitter (FR-A-2320557), a converter is provided which consists of a stationary part which generates a magnetic field and a second part which is moved by the valve needle. The magnetic field-producing part of the transducer is designed as a screw which is screwed into a threaded bore extending from the rear end of the nozzle holder and can be adjusted as a whole in the threaded bore for the purpose of axial adjustment relative to the second part of the transducer. This version requires a special design of the nozzle holder, in which the fuel supply line is not inserted centrally into the nozzle holder, as is usual, but laterally.

Bei anderen bekannten Einspritzdüsen mit einer der Signalgabe dienenden Induktionsspule, welcher ein von der Ventilnadel beeinflußter Anker und ein Spulenkern zugeordnet sind (DE-A-3 137 761, älteres nationales Recht) ist die Anordnung so getroffen, daß zwar die Kraftstoff-Zuleitung zentral eingeführt ist, der Spulenkern jedoch nicht vom rückseitigen Stirnende der Düsenhalters zugänglich ist und zum Zweck der Einstellung eines Anfangsluftspaltes nicht axial verstellt werden kann. Bei Einspritzdüsen ohne integrierten Signalgeber ist es ferner bekannt, das von der Ventilnadel abgekehrte Ende der Schließfeder an einem im Düsenhalter axial verschiebbar gelagerten Bolzen abzustützen, der seinerseits an einem als Anschlag dienenden Gewindestift anliegt, der in eine Gewindebohrung des Düsenhalters eingeschraubt und von außen einstellbar ist (FR-A-2136 705). Auch bei dieser Anordnung ist die Kraftstoff-Zuleitung nicht zentral, sondern von der Seite her in den Düsenhalter eingeführt.In other known injection nozzles with an induction coil serving for signaling, to which an armature influenced by the valve needle and a coil core are assigned (DE-A-3 137 761, earlier national law), the arrangement is such that the fuel feed line is introduced centrally is, however, the coil core is not accessible from the rear end of the nozzle holder and can not be adjusted axially for the purpose of setting an initial air gap. In the case of injection nozzles without an integrated signal transmitter, it is also known to support the end of the closing spring which is remote from the valve needle on a bolt which is axially displaceably mounted in the nozzle holder and which in turn rests on a set screw which serves as a stop and which is screwed into a threaded bore of the nozzle holder and is adjustable from the outside (FR-A-2136 705). In this arrangement, too, the fuel supply line is not central, but is inserted into the nozzle holder from the side.

Vorteile der ErfindungAdvantages of the invention

Die erfindungsgemäße Anordnung mit den kennzeichnenden Merkmalen des Patentanspruches 1 hat demgegenüber den Vorteil, daß der Spulenkern zum Einstellen des Anfangsluftspaltes oder der anfänglichen Größe der sich gegenüberliegenden Polflächen an Spulenkern und Anker auch nach dem Zusammenbau der Einspritzdüse noch axial verstellt werden kann, ohne daß für den Düsenhalter eine von der üblichen Bauart mit zentraler Einführung der Kraftstoff-Zuleitung abweichende Sonderbauform vorgesehen werden muß. Der Anfangsluftspalt bzw. die anfängliche Größe der Polflächen kann beispielsweise durch elektronische Messung der Anfangsinduktivität der Induktionsspule oder auch mechanisch dadurch ermittelt werden, daß vor dem Zusammenbau der Einspritzdüse der Abstand der maßgebenden Flächen am Anker und am Spulenkern gegenüber einer Bezugsebene, beispielsweise der Trennungsebene zwischen Düsenhalter und zwischen Scheibe bzw. Düsenkörper, festgestellt wird. Nach dem Zusammenbau der Einspritzdüse kann das die axiale Lage des Spulenkerns bestimmende Einstellglied entsprechend des tatsächlich gewünschten Anfangswertes von Luftspalt oder Polflächengröße nachgestellt und anschließend der Spulenkern in der eingestellten Lage festgelegt, z. B. durch Verstemmen festgeklemmt werden.The arrangement according to the invention with the characterizing features of claim 1 has the advantage that the coil core for adjusting the initial air gap or the initial size of the opposing pole faces on the coil core and armature can still be adjusted axially even after the injection nozzle has been assembled, without that for the Nozzle holder must be provided for a special design that deviates from the usual design with a central introduction of the fuel supply line. The initial air gap or the initial size of the pole faces can be determined, for example, by electronic measurement of the initial inductance of the induction coil, or mechanically by the distance between the relevant surfaces on the armature and the coil core relative to a reference plane, for example the separation plane between the nozzle holder, before the injection nozzle is assembled and between the disc or nozzle body. After the injection nozzle has been assembled, the adjusting element which determines the axial position of the coil core can be readjusted in accordance with the actually desired initial value of the air gap or pole face size and then the coil core can be fixed in the set position, e.g. B. be clamped by caulking.

Durch die in den Unteransprüchen aufgeführten Maßnahmen sind vorteilhafte Weiterbildungen der im Hauptanspruch angegebenen Anordnung möglich.Advantageous developments of the arrangement specified in the main claim are possible through the measures listed in the subclaims.

Eine einfache Ausführung ergibt sich, wenn die Bohrung zur Aufnahme des Einstellgliedes im spitzen Winkel in die den Spulenkern bzw. den Spulenkörper aufnehmende Bohrung mündet. Das Einstellglied kann in diesem Fall ein Bolzen sein, der in die Bohrung bleibend oder nur bei der Einstellung vorübergehend eingeführt wird.A simple design results if the bore for receiving the adjusting member opens at an acute angle into the bore receiving the coil core or the bobbin. In this case, the adjusting element can be a bolt which is inserted into the bore permanently or only temporarily during adjustment.

Für einen vorteilhaften Verlauf der magnetischen Feldlinien wird vorgeschlagen, daß der Spulenkern in einem Ansatz des Spulenkörpers verschiebbar geführt und an der vom Anker abgekehrten Seite mit einem Zapfen versehen ist, welcher passend in einen verengten Bohrungsabschnitt im Düsenhalter greift.For an advantageous course of the magnetic field lines, it is proposed that the coil core be displaceably guided in an extension of the coil body and provided on the side facing away from the armature with a pin which fits into a narrowed bore section in the nozzle holder.

Der von der Ventilnadel beeinflußte Anker bzw. ein den Anker mit der Ventilnadel verbindendes Gestängeteil kann besonders kurz ausgeführt sein, wenn der Spulenkern die Induktionsspule axial durchsetzt und in dieser verschiebbar geführt ist. Die Anordnung kann jedoch auch so getroffen sein, daß sowohl der Spulenkern als auch der Anker in die Induktionsspule eintauchen und der magnetische Luftspalt zwischen diesen Teilen innerhalb der Induktionsspule angeordnet ist.The armature influenced by the valve needle or a rod part connecting the armature to the valve needle can be made particularly short if the coil core passes axially through the induction coil and is displaceably guided therein. However, the arrangement can also be such that both the coil core and the armature are immersed in the induction coil and the magnetic air gap is arranged between these parts within the induction coil.

Die zur Aufnahme der Induktionsspule und des Spulenkerns dienenden Bohrungen im Düsenhalter können gegen Leckölaustritt auf einfache Weise dadurch abgedichtet sein, daß der Spulenkörper und/oder der Spulenkern am Außenumfang einen Dichtring trägt.The bores in the nozzle holder which serve to receive the induction coil and the coil core can be sealed in a simple manner against leakage oil leakage in that the coil body and / or the coil core carries a sealing ring on the outer circumference.

Zeichnungdrawing

Zwei Ausführungsbeispiele der Erfindung sind in der Zeichnung dargestellt und in der nachfolgenden Beschreibung näher erläutert. Es zeigen Figur 1 das erste Ausführungsbeispiel teils im Längsschnitt und teils in Seitenansicht, und Figur 2 einen gegenüber Figur 1 vergrößerten Teil-Längsschnitt durch das zweite Ausführungsbeispiel.Two embodiments of the invention are shown in the drawing and in the following description explained in more detail. FIG. 1 shows the first exemplary embodiment partly in longitudinal section and partly in side view, and FIG. 2 shows a partial longitudinal section through the second exemplary embodiment that is enlarged compared to FIG.

Beschreibung der AusführungsbeispieleDescription of the embodiments

Die Einspritzdüse nach Figur 1 hat einen Düsenhalter 10, gegen den ein Zwischenplatte 11 und ein Düsenkörper 12 durch eine Überwurfmutter 13 gespannt sind. Im Düsenkörper 12 ist eine Ventilnadel 14 verschiebbar gelagert, auf welche über ein Druckstück 15 eine Schließfeder 16 einwirkt, die in einer Federkammer 17 des Düsenhalters 10 untergebracht ist. Die Ventilnadel 14 arbeitet mit einem nach innen gekehrten Ventilsitz im Düsenkörper 12 zusammen und führt ihren Öffnungshub entgegen der Strömungsrichtung des Kraftstoffs aus. Die Führungsbohrung der Ventilnadel 14 ist wie üblich an einer Stelle zu einem Druckraum erweitert, in dessen Bereich die Ventilnadel 14 eine dem Ventilsitz zugekehrte Druckschulter hat und der über Kanäle 18, 19, 20 und 21 in der Zwischenscheibe 11 bzw. dem Düsenhalter 10 mit einem Kraftstoff-Anschluß stutzen 22 des Düsenhalters 10 verbunden ist. Der an der Druckschulter der Ventilnadel 14 angreifende Kraftstoffdruck schiebt die Ventilnadel 14 entgegen der Kraft der Schließfeder 16 nach oben, bis eine nicht sichtbare Schulter an der Ventilnadel 14 gegen die untere Stirnseite der Zwischenscheibe 11 stößt und den weiteren Aufwärtshub der Ventilnadel 14 begrenzt.The injection nozzle according to FIG. 1 has a nozzle holder 10, against which an intermediate plate 11 and a nozzle body 12 are clamped by a union nut 13. A valve needle 14 is displaceably mounted in the nozzle body 12, on which a closing spring 16 acts via a pressure piece 15 and is accommodated in a spring chamber 17 of the nozzle holder 10. The valve needle 14 cooperates with an inward-facing valve seat in the nozzle body 12 and executes its opening stroke against the direction of flow of the fuel. The guide bore of the valve needle 14 is, as usual, expanded at one point to a pressure chamber, in the area of which the valve needle 14 has a pressure shoulder facing the valve seat and which has channels 18, 19, 20 and 21 in the intermediate disk 11 or the nozzle holder 10 Fuel connection nozzle 22 of the nozzle holder 10 is connected. The fuel pressure acting on the pressure shoulder of the valve needle 14 pushes the valve needle 14 upward against the force of the closing spring 16 until an invisible shoulder on the valve needle 14 abuts against the lower end face of the intermediate disk 11 and limits the further upward stroke of the valve needle 14.

Die Schließfeder 16 stützt sich über eine Scheibe 24 an einem Flanschteil 25 aus magnetisch leitfähigem Stoff ab, welcher an einer Schulter 26 des Düsengehäuses 10 anliegt, die am Übergang der Federkammer 17 zu einer mehrfach abgestuften Sackbohrung 28 gebildet ist. In diese ist eine als Ganzes mit der Bezugszahl 30 bezeichnete Induktionsspule eingesteckt, deren Wicklung 31 auf einem Spulenkörper 32 aufgebracht ist. Flanschteil 25 und Spulenkörper 32 sind mittels eines geeigneten Verfahrens miteinander fest verbunden (geklebt, umspritzt). Im Flanschteil 25 und im Spulenkörper 32 ist ein aus magnetisch leitendem Stoff bestehender Ankerbolzen 34 verschiebbar geführt, der über eine Verlängerung 35 mit dem Druckstück 15 fest verbunden ist und sich dadurch mit der Ventilnadel 14 in beiden Richtungen mitbewegt. Die Verlängerung 35 ist vorteilhaft als Kunststoffteil ausgeführt, welches mit dem Ankerbolzen 34 und dem Druckstück 15 durch ein geeignetes Verfahren fest verbunden ist. Durch diese Ausbildung der Verlängerung 35 ist sichergestellt, daß sich der Ankerbolzen 34 klemmfrei im Flanschteil 25 und dem Spulenkörper 32 verschieben kann.The closing spring 16 is supported by a washer 24 on a flange part 25 made of magnetically conductive material, which abuts a shoulder 26 of the nozzle housing 10, which is formed at the transition from the spring chamber 17 to a multi-step blind bore 28. An induction coil designated as a whole with the reference number 30 is inserted into the latter, the winding 31 of which is applied to a coil body 32. Flange part 25 and coil body 32 are firmly connected to one another by means of a suitable method (glued, overmoulded). In the flange part 25 and in the coil body 32, an anchor bolt 34 made of magnetically conductive material is slidably guided, which is firmly connected to the pressure piece 15 via an extension 35 and thereby moves with the valve needle 14 in both directions. The extension 35 is advantageously designed as a plastic part which is firmly connected to the anchor bolt 34 and the pressure piece 15 by a suitable method. This design of the extension 35 ensures that the anchor bolt 34 can move without jamming in the flange part 25 and the coil body 32.

Der Spulenkörper 32 ist auf der vom Flanschteil 25 abgekehrten Stirnseite mit einem nabenförmigen Ansatz 38 versehen, in welchem ein mit dem Ankerbolzen 34 zusammenwirkender, aus magnetisch leitenden Stoff bestehender Spulenkern 40 verschiebbar gelagert ist. Dieser hat in seinem den Ankerbolzen 34 zugekehrten Stirnende eine Sackbohrung 41, deren Durchmesser um das Doppelte des Restluftspaltes zwischen dem Ankerbolzen 34 und dem Spulenkörper 40 größer als der Durchmesser des Ankerbolzens 34 ist. Auf der anderen Seite ist der Spulenkern 40 mit einem Zapfen 42 versehen, der mit metallischem Berührungsschluß passend in den abgestuften inneren Abschnitt 43 der Sackbohrung 28 greift. Der Zapfen 42 liegt mit seiner Stirnseite am vorderen Ende einer Stiftschraube 44 an, welche in eine Gewindebohrung 45 eingedreht ist, die im spitzen Winkel a zur Längsachse der Einspritzdüse verläuft.The coil former 32 is provided on the end face facing away from the flange part 25 with a hub-shaped extension 38, in which a coil core 40, which cooperates with the anchor bolt 34 and is made of magnetically conductive material, is slidably mounted. This has a blind bore 41 in its front end facing the anchor bolt 34, the diameter of which is larger than the diameter of the anchor bolt 34 by twice the residual air gap between the anchor bolt 34 and the coil former 40. On the other hand, the coil core 40 is provided with a pin 42, which fits into the stepped inner section 43 of the blind bore 28 with a metallic contact. The end face of the pin 42 rests on the front end of a stud screw 44 which is screwed into a threaded bore 45 which extends at an acute angle a to the longitudinal axis of the injection nozzle.

Im Düsenhalter 10 ist eine seitliche Ausnehmung 48 vorgesehen, welche die Bohrung 28 im Bereich ihres den Ansatz 38 aufnehmenden mittleren Abschnittes 49 anschneidet. In der Ausnehmung 48 sind Mittel 50 zum abgedichteten Herausführen der Wicklungsenden der Induktionsspule 30 und Verbinden mit einem weiterführenden Kabel 51 vorgesehen, über welches eine Auswerteschaltung an die Einspritzdüse anschließbar ist. Zum Abdichten der Federkammer 17 gegen die Ausnehmung 48 und die Gewindebohrung 45 sind außerdem ein Dichtring 52 am Umfang des Spulenkörpers 32 und ein Dichtring 53 am Umfang des Spulenkerns 40 vorgesehen. Im Ankerbolzen 34 sind eine Längsbohrung 54 und eine Querbohrung 55 zur Druckentlastung der Sackbohrung 41 gegen die Federkammer 17 vorgesehen.A lateral recess 48 is provided in the nozzle holder 10, which cuts the bore 28 in the region of its central section 49 receiving the attachment 38. Means 50 are provided in the recess 48 for sealingly leading out the winding ends of the induction coil 30 and connecting them to a further cable 51, via which an evaluation circuit can be connected to the injection nozzle. To seal the spring chamber 17 against the recess 48 and the threaded bore 45, a sealing ring 52 is also provided on the circumference of the coil former 32 and a sealing ring 53 on the circumference of the coil core 40. A longitudinal bore 54 and a transverse bore 55 are provided in the anchor bolt 34 to relieve the pressure in the blind bore 41 against the spring chamber 17.

Das magnetische Feld der Induktionsspule 30 führt über den Ankerbolzen 34, das Flanschteil 25, den inneren Bereich des Düsenhalters 10, den Spulenkern 40 und den Luftspalt, der zwischen dem Spulenkern 40 und dem Ankerbolzen 34 gebildet ist. Beim gewählten Ausführungsbeispiel ist die Anordnung so getroffen, daß bereits bei geschlossenem Ventil der Ankerbolzen 34 ein ganz geringes Stück weit in die Sackbohrung 41 eintaucht. Dadurch ist bereits in der Ausgangslage der kleinste Luftspalt zwischen Ankerbolzen 34 und Spulenkern 40 vorhanden, der sich aus dem Radialspiel zwischen diesen Teilen ergibt. Die signalerzeugende Änderung des magnetischen Feldwiderstandes wird dadurch hervorgerufen, daß beim Öffnungshub der Ventilnadel 14 der Ankerbolzen 34 tiefer in die Sackbohrung 41 eintaucht und sich dadurch die den Luftspalt begrenzenden Polflächen der Teile vergrößern.The magnetic field of the induction coil 30 leads via the armature bolt 34, the flange part 25, the inner region of the nozzle holder 10, the coil core 40 and the air gap which is formed between the coil core 40 and the armature bolt 34. In the selected embodiment, the arrangement is such that even when the valve is closed, the anchor bolt 34 dips a very small amount into the blind bore 41. As a result, the smallest air gap between the armature bolt 34 and the coil core 40, which results from the radial play between these parts, is already present in the starting position. The signal-generating change in the magnetic field resistance is caused by the fact that during the opening stroke of the valve needle 14 the anchor bolt 34 dips deeper into the blind bore 41 and the pole faces of the parts delimiting the air gap thereby increase.

Die bei geschlossenem Ventil vorhandene Anfangsgröße der Polflächen kann durch die Stiftschraube 44 auf jeden gewünschten Wert eingestellt werden. Der jeweils eingestellte Wert kann.beispielsweise durch Erfassung der Induktivität der Spule mittels einer elektronischen Schaltung ermittelt werden. Es ist aber auch eine Einstellung durch rein mechanisches Messen möglich. Zu diesem Zweck wird vor dem Zusammenbau der Einspritzdüse z. B. der Abstand der freien Stirnfläche des Ankerbolzens 34 von der oberen Stirnseite der Zwischenscheibe 11, so wie der Abstand der freien Stirnseite des Spulenkerns 40 von der unteren Stirnseite des Düsenhalters 10 ermittelt. Durch entsprechendes Drehen der Stiftschraube 44 läßt sich danach die gewünschte Differenz der beiden Abstände leicht einstellen. Nach dem Einstellen wird der Spulenkern 40 durch Verstemmen mittels eines in die .Ausnehmung 48 eingeführten Werkzeugs an der Stelle 58 im Düsenhalter 10 festgelegt.The initial size of the pole faces when the valve is closed can be set to any desired value by means of the stud screw 44. The value set in each case can be determined, for example, by detecting the inductance of the coil by means of an electronic circuit. However, adjustment by purely mechanical measurement is also possible. For this purpose, before assembling the injector z. B. the distance of the free end face of the anchor bolt 34 from the upper end face of the washer 11, such as the distance of the free end face of the coil core 40 from the lower end face of the nozzle holder 10 is determined. The desired difference between the two distances can then be easily adjusted by appropriately turning the stud screw 44. After the setting, the coil core 40 is fixed at a point 58 in the nozzle holder 10 by caulking by means of a tool inserted into the recess 48.

Die erfindungsgemäße Anordnung ist nicht auf die dargestellte und beschriebene Konstruktion eingeschränkt. Der Luftspalt könnte beispielsweise auch zwischen ebenen, senkrecht zur Längsachse der Einspritzdüse ausgerichteten Polflächen gebildet sein, wobei die Signalgabe allein durch Änderung der Luftspaltlänge hervorgerufen wird. Ferner ist es denkbar, eine oder beide Polflächen an Ankerbolzen 34 und Spulenkern 40 bzw. Sackbohrung 41 konisch auszuführen, so daß sich beim Hub der Ventilnadel 14 sowohl eine Verkleinerung des (mittleren) Luftspalts als auch eine Vergrößerung der den Luftspalt begrenzenden Polflächen ergibt. Besonders vorteilhaft ist eine Anordnung, bei welcher in Schließlage der Ventilnadel 14 der Ankerbolzen 34 noch nicht in die Sackbohrung 41 eintaucht, weil sich dabei besonders große Änderunen des magnetischen Widerstandes über den Ventilnadelhub erzielen lassen.The arrangement according to the invention is not restricted to the construction shown and described. The air gap could, for example, also be formed between plane pole faces oriented perpendicular to the longitudinal axis of the injection nozzle, the signal being generated solely by changing the length of the air gap. Furthermore, it is conceivable to design one or both pole faces on armature bolts 34 and coil core 40 or blind bore 41 so that there is both a reduction in the (middle) air gap and an increase in the pole faces delimiting the air gap when the valve needle 14 is lifted. An arrangement is particularly advantageous in which, when the valve needle 14 is in the closed position, the anchor bolt 34 is not yet immersed in the blind bore 41, because particularly large changes in the magnetic resistance can be achieved via the valve needle stroke.

Ferner ist die erfindungsgemäße Einstellbarkeit des Spulenkerns auch nicht darauf beschränkt, daß der Spulenkern an der von der Ventilnadel 14 abgekehrten Seite der Wicklung der Induktionsspule angeordnet ist und der Ankerbolzen den Spulenkörper durchsetzt.Furthermore, the adjustability of the coil core according to the invention is also not limited to the fact that the coil core is arranged on the side of the winding of the induction coil remote from the valve needle 14 and the armature bolt passes through the coil body.

Beim Ausführungsbeispiel nach Figur 2 ist die Anordnung so getroffen, daß ein Spulenkern 60 durch die Wicklung 61 einer als Ganzes mit der Bezugszahl 62 bezeichneten Induktionsspule hindurchgeführt ist und ein aus der Wicklung 61 herausragendes verdicktes Stirnende 63 hat, in welchem die mit dem Ankerbolzen 34 zusammenarbeitende Sackbohrung 41 angeordnet ist. Der Ankerbolzen 34 ist hier wesentlich kürzer als beim Ausführungsbeispiel nach Figur 1 ausgebildet und außerdem an seinem freien Stirnende konisch zulaufend geformt, so daß sich bei dem Ventilnadelhüben sowohl Luftspaltverkleinerungen als auch Polflächenvergrößerungen ergeben. Zum Festhalten der Induktionsspule 62 und zur Weiterleitung der magnetischen Feldlinien ist auch hier ein aus magnetisch leitendem Stoff bestehendes Flanschteil 65 vorgesehen, welches über ein magnetisch isolierendes Formteil 66 am Stirnende 63 des Spulenkerns 60 anliegt und mit diesem z. B. durch Klebstoff verbunden ist. Das Formteil 66 dient gleichzeitig zum Führen des Ankerbolzens 34. Zum Verhindern des Leckölaustritts aus der Federkammer 17 ist ein Dichtring 67 zwischen Düsenhalter und Stirnende 63 des Spulenkerns 60 gespannt. Der Spulenkern 60 ist wie beim Ausführungsbeispiel nach Fig. 1 durch Verstemmen im Düsenhalter festgelegt.In the exemplary embodiment according to FIG. 2, the arrangement is such that a coil core 60 is passed through the winding 61 of an induction coil, designated as a whole by the reference number 62, and has a thickened end face 63 protruding from the winding 61, in which the end cooperating with the armature bolt 34 Blind bore 41 is arranged. The anchor bolt 34 is here much shorter than in the embodiment according to FIG. 1 and, moreover, tapered at its free end, so that both air gap reductions and increases in the pole area result in the valve needle lifts. To hold the induction coil 62 and to forward the magnetic field lines, a flange part 65 consisting of magnetically conductive material is also provided here, which abuts the end face 63 of the coil core 60 via a magnetically insulating molded part 66 and connects it with this z. B. is connected by adhesive. The molded part 66 is also used to guide the anchor bolt 34. To prevent leakage oil leakage from the spring chamber 17, a sealing ring 67 is stretched between the nozzle holder and the front end 63 of the coil core 60. As in the exemplary embodiment according to FIG. 1, the coil core 60 is fixed in the nozzle holder by caulking.

Die Sackbohrung 41 könnte bei diesem Ausführungsbeispiel anstelle im Spulenkern 60 auch im Ankerbolzen 34 gebildet sein, welcher zu diesem Zweck mit einem verdickten Kopfteil zu versehen wäre.In this exemplary embodiment, the blind bore 41 could also be formed in the armature bolt 34 instead of in the coil core 60, which would be provided with a thickened head part for this purpose.

Bei einem anderen, nicht gezeigten Ausführungsbeispiel tauchen sowohl der Spulenkern als auch der Ankerbolzen in die Induktionsspule ein, wobei der magnetische Luftspalt innerhalb der Induktionsspule gebildet ist.In another exemplary embodiment, not shown, both the coil core and the anchor bolt are immersed in the induction coil, the magnetic air gap being formed within the induction coil.

Claims (7)

1. Fuel injection nozzle for internal combustion engines, with a nozzle body (12), in which a valve seat is formed and a valve needle (14) is displaceably guided, which is impinged by a closing spring (16) and, oppositely to it, by the fuel pressure, and moves in the opening stroke against the direction of flow of the fuel, and furthermore with a nozzle holder (10), on which the nozzle body (12) is firmly clamped and which has a chamber for accommodating the closing spring (16) and an induction coil (30), which serves for signalling in a way dependent on the needle stroke or needle speed and to which are assigned an armature (34), influenced by the valve needle (14), and a coil core (40, 60), against which the armature (34) moves in the opening stroke and the axial position of which is adjustable from outside, characterized in that the coil core (40, 60) is mounted axially displaceably in the nozzle holder (10) or in the coil body (32), and in that the end section (42) of the coil core (40, 60) facing away from the armature (34) engages and fits in a bore section (43) in the nqzzle holder (10), constricted with respect to a bore section accommodating the coil body, and forms on the face side a stop shoulder which faces away from the armature (34) and which can be brought into contact with an adjustment member (44) which is designed separate from the coil core (40, 60) and which can be inserted into a bore (45) in the nozzle holder (10) arranged at an angle to the nozzle axis, and in that the coil core (40, 60) can be fixed secure against axial displacement in the nozzle holder (10) in any position of its adjustment range.
2. Injection nozzle according to Claim 1, characterized in that the bore (45) for accommodating the adjustment member (44) opens out at an acute angle (a) with respect to the fuel connection side into the bore (28) accommodating the coil core (40, 60) or the coil body (32).
3. Injection nozzle according to Claim 1 or 2, characterized in that the coil core (40) is displaceably guided in an extension (38) of the coil body (32) and is provided on the face side facing away from the armature (34) with a pin (42) which engages and fits into the constricted bore section (43) in the nozzle holder (10).
4. Injection nozzle according to Claim 1, characterized in that the coil core (60) passes axially through the induction coil (62) and is displaceably guided in the latter (Figure 2).
5. Injection nozzle according to Claim 1, characterized in that both the coil core and the armature enter into the induction coil and the magnetic air gap is formed within the induction coil.
6. Injection nozzle according to one of the preceding claims, characterized in that the coil body (32) and/or the coil core (40, 60) bears a sealing ring (52, 53, 67) on its outer periphery.
7. Injection nozzle according to one of the preceding claims, in which the closing spring acts on the valve needle via a thrust piece, characterized in that the armature (34) is connected to the thrust piece (15) via an elastically deformable intermediate element (35), in particular via a bolt made of plastic.
EP83106279A 1982-07-27 1983-06-28 Fuel injector for an internal-combustion engine Expired EP0099991B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19823227989 DE3227989A1 (en) 1982-07-27 1982-07-27 FUEL INJECTION NOZZLE FOR INTERNAL COMBUSTION ENGINES
DE3227989 1982-07-27

Publications (2)

Publication Number Publication Date
EP0099991A1 EP0099991A1 (en) 1984-02-08
EP0099991B1 true EP0099991B1 (en) 1987-03-04

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EP83106279A Expired EP0099991B1 (en) 1982-07-27 1983-06-28 Fuel injector for an internal-combustion engine

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US (1) US4502326A (en)
EP (1) EP0099991B1 (en)
JP (1) JPS5934476A (en)
DE (2) DE3227989A1 (en)

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Publication number Priority date Publication date Assignee Title
DE3343269C1 (en) * 1983-11-30 1985-04-04 Daimler-Benz Ag, 7000 Stuttgart Device for indirect contactless electrical measurement of small distances
US4573349A (en) * 1984-06-28 1986-03-04 International Harvester Company Needle position indicator for a fuel injection nozzle holder
DE3515264A1 (en) * 1985-04-27 1986-11-27 Robert Bosch Gmbh, 7000 Stuttgart FUEL INJECTION NOZZLE FOR INTERNAL COMBUSTION ENGINES
GB8516127D0 (en) * 1985-06-26 1985-07-31 Lucas Ind Plc Fuel injection nozzle
DE3864772D1 (en) * 1987-07-21 1991-10-17 Nippon Denso Co METHOD FOR ADJUSTING THE FUEL INJECTION AMOUNT OF AN ELECTROMAGNETIC FUEL INJECTION VALVE.
DE3736198A1 (en) * 1987-10-26 1989-05-18 Voest Alpine Automotive FUEL INJECTION NOZZLE FOR INTERNAL COMBUSTION ENGINES
DE3840339A1 (en) * 1988-11-30 1990-05-31 Bosch Gmbh Robert FUEL INJECTION NOZZLE FOR INTERNAL COMBUSTION ENGINES
DE4108416C2 (en) * 1991-03-15 2000-05-18 Bosch Gmbh Robert Fuel injection nozzle for internal combustion engines
DE4341102A1 (en) * 1993-12-02 1995-06-08 Bosch Gmbh Robert Fuel injector with needle position sensor
US5895844A (en) * 1997-05-29 1999-04-20 Outboard Marine Corporation Precise fuel flow measurement with modified fluid control valve

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FR2136705A5 (en) * 1971-04-27 1972-12-22 Maschf Augsburg Nuernberg Ag

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US2365592A (en) * 1940-05-30 1944-12-19 Kapella Ltd Electrical measuring apparatus
GB729431A (en) * 1951-09-25 1955-05-04 Leslie Hartridge Apparatus and devices for testing fuel injection pumps and nozzles for internal combustion compression ignition engines
GB754917A (en) * 1953-11-04 1956-08-15 Daimler Benz Ag Apparatus for measuring the movement of valve needles, particularly for fuel injection nozzles of internal combustion engines
GB1549768A (en) * 1975-08-02 1979-08-08 Lucas Industries Ltd Movement transducers
DE3004424A1 (en) * 1980-02-07 1981-08-13 Robert Bosch Gmbh, 7000 Stuttgart FUEL INJECTOR HOLDER

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Publication number Priority date Publication date Assignee Title
FR2136705A5 (en) * 1971-04-27 1972-12-22 Maschf Augsburg Nuernberg Ag

Also Published As

Publication number Publication date
DE3227989A1 (en) 1984-02-02
US4502326A (en) 1985-03-05
JPH0425433B2 (en) 1992-04-30
DE3370055D1 (en) 1987-04-09
JPS5934476A (en) 1984-02-24
EP0099991A1 (en) 1984-02-08

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