EP0096312B1 - Fuel injector for an internal-combustion engine - Google Patents

Fuel injector for an internal-combustion engine Download PDF

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Publication number
EP0096312B1
EP0096312B1 EP83105257A EP83105257A EP0096312B1 EP 0096312 B1 EP0096312 B1 EP 0096312B1 EP 83105257 A EP83105257 A EP 83105257A EP 83105257 A EP83105257 A EP 83105257A EP 0096312 B1 EP0096312 B1 EP 0096312B1
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EP
European Patent Office
Prior art keywords
valve needle
damping
stroke
fuel
return spring
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EP83105257A
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German (de)
French (fr)
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EP0096312A1 (en
Inventor
Dietrich Dipl.-Ing. Trachte
Helmut Ing. Grad. Giess
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Robert Bosch GmbH
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Robert Bosch GmbH
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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
    • F02M61/00—Fuel-injectors not provided for in groups F02M39/00 - F02M57/00 or F02M67/00
    • F02M61/04—Fuel-injectors not provided for in groups F02M39/00 - F02M57/00 or F02M67/00 having valves, e.g. having a plurality of valves in series
    • F02M61/08—Fuel-injectors not provided for in groups F02M39/00 - F02M57/00 or F02M67/00 having valves, e.g. having a plurality of valves in series the valves opening in direction of fuel flow
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M61/00—Fuel-injectors not provided for in groups F02M39/00 - F02M57/00 or F02M67/00
    • F02M61/16—Details not provided for in, or of interest apart from, the apparatus of groups F02M61/02 - F02M61/14
    • F02M61/20—Closing valves mechanically, e.g. arrangements of springs or weights or permanent magnets; Damping of valve lift
    • F02M61/205—Means specially adapted for varying the spring tension or assisting the spring force to close the injection-valve, e.g. with damping of valve lift

Definitions

  • the one controlling the opening cross section Valve needle coupled to a damping device.
  • the damping device which has a damping chamber formed by a piston and a cylinder and can be acted upon by a throttle, is designed in such a way that the damping already before Is made ineffective at the end of the opening stroke of the valve needle.
  • the arrangement according to the invention with the characterizing features of the main claim has the advantage that a damping of the opening movement of the valve needle and the spraying time which largely corresponds to the requirements is automatically set at each operating point of the internal combustion engine.
  • damping always takes place immediately at the beginning of the opening stroke of the valve needle.
  • the mutually movable parts of the damping device consisting of cylinder and piston always return to their starting position when the valve needle closes.
  • the invention is based on the knowledge that the time between two injection processes becomes shorter with increasing speed and that there is a greater stroke of the valve needle with larger injection quantities.
  • the time of activation of the damping means for the next opening stroke of the valve needle is delayed compared to the time of the beginning of this opening stroke, the greater the previous valve needle stroke was and ever shorter the time between successive strokes, ie the greater the speed of the internal combustion engine.
  • the valve needle can therefore perform an undamped partial stroke at the beginning of an opening stroke, the length of which is automatically matched to the respective operating parameters of the internal combustion engine.
  • the damping effect can be changed by shifting the start of damping from the start of injection. It is thereby achieved that the entire duration of an injection process at high speed and a large quantity can be shortened even further compared to an arrangement with initial damping of the valve needle, although a long spraying duration is maintained at low speed / quantity.
  • the duration of an injection process can be made so short that when the injection system is adapted to the operating conditions, the injection duration can be changed within further limits than before.
  • the arrangement could also be such that the damping remains effective over the entire opening stroke of the valve needle in the lower speed and load range or only in the critical point of idling. In some cases it could also be advisable to delay the damping means a minimum, i.e. to provide a minimum free stroke of the valve needle, which is present in all operating points of the internal combustion engine.
  • the piston of the damping device is formed by the inlet-side end section of the valve needle 26 and serves as a cylinder a cap attached to this end section.
  • FIG. 1 shows an injection nozzle for a diesel internal combustion engine in longitudinal section
  • FIGS. 2 to 4 show functional diagrams of the sequence of movements of the valve needle 26 and the cap 48 of the injection nozzle according to FIG. 1 belonging to a damping device, specifically FIG. 2 in principle, FIG. 3 at low speed - / Load range and Figure 4 in the high speed / load range of an internal combustion engine.
  • the injection nozzle according to FIG. 1 has a nozzle body 10 which is clamped to a nozzle holder 14 by a union nut 12.
  • a sleeve 16 Arranged between the nozzle body 10 and the nozzle holder 14 is a sleeve 16 which has an inwardly directed shoulder 18 which divides a chamber 20 from a chamber 22 of larger diameter inside the injection nozzle.
  • a valve seat 24 is formed in the nozzle body 10 and a valve needle 26 is displaceably mounted, the sealing cone 27 of which is pressed against the valve seat 24 by a closing spring 28.
  • the closing spring 28 is supported on the nozzle body 10 and engages via a flange part 30 on a support disk 32, which in turn is supported on a shoulder 34 det valve needle 26.
  • an inlet bore 36 is formed, which opens into the chamber 20, which is connected to the chamber 22 via an opening 38 surrounded by the shoulder 18. From this, a bore 40 in the nozzle body 10 leads into an annular space 42, which is formed between the central bore wall of the nozzle body 10 and the circumference of a section 44 of the valve needle 26 with a reduced diameter and extends up to the valve seat 24. Between the flange part 30 and the nozzle body 10 there is a distance hg in the illustrated closed position, which corresponds to the total stroke of the valve needle 26. The valve needle 26 is displaced outward in the opening direction by the fuel pressure against the closing spring 28 until the flange part 30 strikes the nozzle body 10. When the valve closes, the closing spring 28 returns the valve needle 26 inward to the closed position shown.
  • a piston-shaped extension 46 adjoins the shoulder 34 of the valve needle 26, which extends through the opening 38 and projects into the chamber 20.
  • the diameter of the piston-shaped extension 46 corresponds to the guide diameter of the valve needle 26.
  • a cap 48 is placed on the extension 46, which has a bottom 50, a jacket part 52 and a flange edge 54.
  • a return spring 56 engages on the cap 48, which surrounds the jacket part 52 and presses the flange edge 54 against the collar of the sleeve 16.
  • transverse slots 58 are provided, through which the fuel can always pass from the chamber 20 into the chamber 22, even when the valve needle is closed.
  • a damping chamber 60 is formed in the cap 48 between the end face of the projection 46 and the base 50, which is connected to the flow path of the fuel in a throttled manner via a throttle bore 62 in the base 50.
  • the projection 46 covers the transverse slots 58 in the axial direction by the path h "which is greater than the total stroke hg of the valve needle 26.
  • the path h i could also be smaller by a minimal amount than the total stroke hg, so that there is still a small undamped partial stroke at the end of an opening stroke of the valve needle 26.
  • the throttle bore 62 could also be partially or completely replaced by a corresponding radial play between the cap 48 and the shoulder 46.
  • the piston-shaped extension 46 of the valve needle 26 and the cap 48 simultaneously form the means for damping the valve needle movement and a time-displacement element, which makes the beginning of the damping dependent on the speed and the size of the valve needle stroke.
  • the damping effect and the time-displacement function are determined by appropriate coordination of the return spring 56 with the throttle bore 62 and others, the inflow and outflow of the fuel into the damping chamber 60 and parameters determining it.
  • the closing stroke of the valve needle 26 is to begin, at which the cap 48 is pushed from the first end position E i to the second end position E2.
  • the cap 48 travels a path ag which, as already mentioned, is somewhat smaller than the total stroke hg of the valve needle 26.
  • the closing stroke is currently point t 2 ended. From then on, the cap 48 begins to move back under the influence of the return spring 56 at a predetermined speed, which is shown in the diagram as the angle a.
  • a new opening stroke of valve needle 26 begins at time t 3. If, as shown in FIG. 2, cap 48 has not yet reached its first end position again at time t 3 , it moves into this end position at approximately the same speed as valve needle 26 returned. It then reaches the first end position at time t 4 . From then on, the cap 48 is held by the shoulder 18 against a further movement in the opening direction of the valve needle 26, as a result of which the damping means described become effective again. This can be seen in the diagram in that the stroke curve has a break point K at time t4. From time t 4 the valve needle 26 is transferred to the stroke end position at a damped, ie at a reduced speed, whereupon the game described is repeated.
  • FIGS. 3 and 4 illustrate that the damping device according to the invention adapts itself automatically to the various operating states of the internal combustion engine.
  • the internal combustion engine runs at low speed and low load, so that the cap 48 reaches its first end position before the start of the next opening stroke.
  • the damping is effective over the entire opening stroke of the valve needle 26.
  • Figure 4 shows an operating state in which the internal combustion engine is running at high speed under high load, in which a large valve needle stroke also occurs. In this case, the next opening stroke begins before the cap 48 has returned to its first end position.
  • the break point K of the stroke curve h of the valve needle 26 has moved further towards the end of the stroke than in the operating state according to FIG. 2, so that a smaller part of the opening movement of the valve needle 26 is damped.
  • FIG. 4 also makes it clear that the break point K moves towards the end of the opening of the valve needle, the faster the injection processes follow one another and the greater the valve needle stroke.
  • the cap 48 is centered on the valve needle 26 and has a sufficiently large radial play with respect to the nozzle holder 14 so that the valve needle 26 can work without jamming.
  • the return spring 56 extends in part over the cap 48 so that in this embodiment the means for partially damping the opening stroke of the valve needle 26 take up little space in the axial direction of the injection nozzle.

Description

Stand der TechnikState of the art

Bei einer Kraftstoff-Einspritzdüsefür Brennkraftmaschinen nach der EP-A1-00 84 662 (nicht vorveröffentlichtes Dokument nach Art. 54(3) EPÜ) ist zum Anpassen des Öffnungsquerschnitts der Einspritzdüse an die unterschiedlichen Forderungen der Brennkraftmaschine bei verschiedenen Drehzahlen und Belastungen die den Öffnungsquerschnitt steuernde Ventilnadel mit einer Dämpfungseinrichtung gekoppelt. Um zu verhindern, daß sich im höheren Drehzahl- oder Lastbereich der Brennkraftmaschine eine zu lange Spritzdauer einstellt, ist die Dämpfungseinrichtung, die eine von einem Kolben und einem Zylinder gebildete, über eine Drossel beaufschlagbare Dampfungskammer hat, so ausgelegt, daß die Dämpfung bereits vor dem Ende des Öffnungshubes der Ventilnadel unwirksam bemacht wird.In the case of a fuel injector for internal combustion engines according to EP-A1-00 84 662 (not prepublished document according to Art. 54 (3) EPC), in order to adapt the opening cross section of the injection nozzle to the different requirements of the internal combustion engine at different speeds and loads, the one controlling the opening cross section Valve needle coupled to a damping device. To prevent a too long spray duration from occurring in the higher speed or load range of the internal combustion engine, the damping device, which has a damping chamber formed by a piston and a cylinder and can be acted upon by a throttle, is designed in such a way that the damping already before Is made ineffective at the end of the opening stroke of the valve needle.

Dadurch kann bereits eine erhebliche Verkürzung der gesamten Dauer eines Einspritzvorgangs erzielt werden. Problematisch ist jedoch, daß der Zeitpunkt des Unwirksamwerdens der Dämpfung nadelhubabhängig festgelegt ist und daher gewisse Kompromisse zwischen Leerlauf- und Vollast der Brennkraftmaschine in Kauf genommen werden müssen.As a result, the entire duration of an injection process can already be considerably shortened. It is problematic, however, that the time at which the damping becomes ineffective is determined as a function of the needle stroke, and therefore certain compromises between idling and full load of the internal combustion engine have to be accepted.

Vorteile der ErfindungAdvantages of the invention

Die erfindungsgemäße Anordnung mit den kennzeichnenden Merkmalen des Hauptanspruchs hat demgegenüber den Vorteil, daß sich in jedem Betriebspunkt der Brennkraftmaschine eine den Anforderungen weitgehend entsprechende Dämpfung der Öffnungsbewegung der Ventilnadel und der Spritzdauer selbsttätig einstellt.The arrangement according to the invention with the characterizing features of the main claim has the advantage that a damping of the opening movement of the valve needle and the spraying time which largely corresponds to the requirements is automatically set at each operating point of the internal combustion engine.

Bei dem durch die GB-A-736 794 bekannten Kraftstoffeinspritzventil gemäß der Gattung des Patentanspruchs 1 erfolgt eine Dämpfung immer unmittelbar mit Beginn des Öffnungshubes der Ventilnadel. Die zueinander beweglichen Teile der Dämpfungseinrichtung bestehend aus Zylinder und Kolben kehren bei dem Schließvorgang der Ventilnadel immer in ihre Ausgangslage zurück.In the fuel injection valve known from GB-A-736 794 according to the preamble of claim 1, damping always takes place immediately at the beginning of the opening stroke of the valve needle. The mutually movable parts of the damping device consisting of cylinder and piston always return to their starting position when the valve needle closes.

Die Erfindung geht von der Erkenntnis aus, daß mit steigender Drehzahl die Zeit zwischen zwei Einspritzvorgängen kürzer wird und daß sich bei größeren Einspritzmengen auch ein größerer Hub der Ventilnadel ergibt. Mit Rücksicht darauf, daß die Rückführung jeweils am Beginn des Schließhubs der Ventilnadel beginnt, wird der Zeitpunkt der Aktivierung der Dämpfungsmittel für den nächsten Öffnungshub der Ventilnadel um so weiter gegenüber dem Zeitpunkt des Beginns dieses Öffnungshubes hinaus gezögert, je größer der vorangegangene Ventilnadelhub war und je kürzer die Zeit zwischen den aufeinanderfolgenden Hüben, d.h. je größer die Drehzahl der Brennkraftmaschine ist. Die Ventilnadel kann daher zu Beginn eines Öffnungshubs einen ungedämpften Teilhub ausführen, dessen Länge selbsttätig auf die jeweiligen Betriebsparameter der Brennkraftmaschine abgestimmt ist.The invention is based on the knowledge that the time between two injection processes becomes shorter with increasing speed and that there is a greater stroke of the valve needle with larger injection quantities. In view of the fact that the return begins at the beginning of the closing stroke of the valve needle, the time of activation of the damping means for the next opening stroke of the valve needle is delayed compared to the time of the beginning of this opening stroke, the greater the previous valve needle stroke was and ever shorter the time between successive strokes, ie the greater the speed of the internal combustion engine. The valve needle can therefore perform an undamped partial stroke at the beginning of an opening stroke, the length of which is automatically matched to the respective operating parameters of the internal combustion engine.

Besonders vorteilhaft ist es, daß' die Dämpfungswirkung veränderbar ist durch zeitliches Verschieben des Dämpfungsbeginns gegenüber dem Einspritzbeginn. Dadurch ist erreicht, daß die gesamte Dauer eines Einspritzvorgangs bei hoher Drehzahl und großer Menge auch gegenüber einer Anordnung mit Anfangsdämpfung der Ventilnadel noch weiter verkürzt werden kann, obwohl bei niederer Drehzahl/ Menge eine lange Spritzdauer erhalten bleibt. Selbst im Vollastbetrieb der Brennkraftmaschine kann die Dauer eines Einspritzvorgangs erfahrungsgemäß so kurz gemacht werden, daß bei der Anpassung der Einspritzanlage an die Betriebsverhältnisse die Spritzdauer in weiteren Grenzen als bisher verändert werden kann. Außerdem ergibt sich die Möglichkeit der unabhängigen Beeinflußung der Spritzdauer bei niedriger und hoher Drehzahl.It is particularly advantageous that the damping effect can be changed by shifting the start of damping from the start of injection. It is thereby achieved that the entire duration of an injection process at high speed and a large quantity can be shortened even further compared to an arrangement with initial damping of the valve needle, although a long spraying duration is maintained at low speed / quantity. Experience has shown that even when the internal combustion engine is operating at full load, the duration of an injection process can be made so short that when the injection system is adapted to the operating conditions, the injection duration can be changed within further limits than before. In addition, there is the possibility of independently influencing the spraying time at low and high speed.

Die Anordnung könnte auch so getroffen sein, däß im unteren Drehzahl- und Lastbereich oder allein im kritischen Punkt Leerlauf die Dämpfung über den gesamten Öffnungshub der Ventilnadel wirksam bleibt. Auch könnte es in manchen Fällen zweckmäßig sein, eine Mindestverzögerung der Dämpfungsmittel, d.h. einen Mindestfreihub der Ventilnadel vorzusehen, der in allen Betriebspunkten der Brennkraftmaschine vorhanden ist.The arrangement could also be such that the damping remains effective over the entire opening stroke of the valve needle in the lower speed and load range or only in the critical point of idling. In some cases it could also be advisable to delay the damping means a minimum, i.e. to provide a minimum free stroke of the valve needle, which is present in all operating points of the internal combustion engine.

Eine einfache und klemmfreie Ausführung ergibt sich, wenn gemäß Anspruch 2 der Kolben der Dämpfungseinrichtung durch den zulaufseitigen Endabschnitt der Ventilnadel 26 gebildet ist und als Zylinder eine auf diesen Endabschnitt aufgesteckte Kappe dient.A simple and jam-free design results if, according to claim 2, the piston of the damping device is formed by the inlet-side end section of the valve needle 26 and serves as a cylinder a cap attached to this end section.

Zeichnungdrawing

Ein Ausführungsbeispiel der Erfindung ist in der Zeichnung dargestellt und in der nachfolgenden Beschreibung näher erläutert. Es zeigen Figur 1 eine Einspritzdüse für eine Dieselbrennkraftmaschine im Längsschnitt, und die Figuren 2 bis 4 Funktionsschaubilder des Bewegungsablaufs der Ventilnadel 26 und der zu einer Dämpfungseinrichtung gehörenden Kappe 48 der Einspritzdüse nach Figur 1, und zwar Figur 2 im Prinzip, Figur 3 im niedrigen Drehzahl-/Lastbereich und Figur 4 im hohen Drehzahl-/Lastbereich einer Brennkraftmaschine.An embodiment of the invention is shown in the drawing and explained in more detail in the following description. 1 shows an injection nozzle for a diesel internal combustion engine in longitudinal section, and FIGS. 2 to 4 show functional diagrams of the sequence of movements of the valve needle 26 and the cap 48 of the injection nozzle according to FIG. 1 belonging to a damping device, specifically FIG. 2 in principle, FIG. 3 at low speed - / Load range and Figure 4 in the high speed / load range of an internal combustion engine.

Beschreibung des AusführungsbeispielsDescription of the embodiment

Die Einspritzdüse nach Figur 1 hat einen Düsenkörper 10, der durch eine Überwurfmutter 12 an einem Düsenhalter 14 festgespannt ist. Zwischen dem Düsenkörper 10 und dem Düsenhalter 14 ist eine Hülse 16 angeordnet, welche eine nach innen gerichtete Schulter 18 hat, die eine Kammer 20 von einer im Durchmesser größeren Kammer 22 im Inneren der Einspritzdüse abteilt. Im Düsenkörper 10 ist ein Ventilsitz 24 gebildet und eine Ventilnadel 26 verschiebbar gelagert, deren Dichtkegel 27 von einer Schließfeder 28 gegen den Ventilsitz 24 gedrückt ist. Die Schließfeder 28 stützt sich am Düsenkörper 10 ab und greift über ein Flanschteil 30 an einer Stützscheibe 32 an, die sich ihrerseits an einer Schulter 34 det Ventilnadel 26 abstützt.The injection nozzle according to FIG. 1 has a nozzle body 10 which is clamped to a nozzle holder 14 by a union nut 12. Arranged between the nozzle body 10 and the nozzle holder 14 is a sleeve 16 which has an inwardly directed shoulder 18 which divides a chamber 20 from a chamber 22 of larger diameter inside the injection nozzle. A valve seat 24 is formed in the nozzle body 10 and a valve needle 26 is displaceably mounted, the sealing cone 27 of which is pressed against the valve seat 24 by a closing spring 28. The closing spring 28 is supported on the nozzle body 10 and engages via a flange part 30 on a support disk 32, which in turn is supported on a shoulder 34 det valve needle 26.

Im Düsenhalter 14 ist eine Zulaufbohrung 36 gebildet, welche in die Kammer 20 einmündet, die über einen von der Schulter 18 umgebenen Durchbruch 38 mit der Kammer 22 verbunden ist. Aus dieser führt eine Bohrung 40 im Düsenkörper 10 in einen Ringraum 42, der zwischen der zentralen Bohrungswand des Düsenkörpers 10 und dem Mantelumfang eines im Durchmesser verkleinerten Abschnittes 44 der Ventilnadel 26 gebildet ist und bis vor den Ventilsitz 24 reicht. Zwischen dem Flanschteil 30 und dem Düsenkörper 10 ist in der dargestellten Schließlage ein Abstand hg vorhanden, welcher dem Gesamthub der Ventilnadel 26 entspricht. Die Ventilnadel 26 wird vom Kraftstoffdruck entgegen der Schließfeder 28 nach außen in Öffnungsrichtung verschoben, bis der Flanschteil 30 am Düsenkörper 10 anschlägt. Beim Schließen des Ventils führt die Schließfeder 28 die Ventilnadel 26 nach innen in die dargestellte Schließlage zurück.In the nozzle holder 14, an inlet bore 36 is formed, which opens into the chamber 20, which is connected to the chamber 22 via an opening 38 surrounded by the shoulder 18. From this, a bore 40 in the nozzle body 10 leads into an annular space 42, which is formed between the central bore wall of the nozzle body 10 and the circumference of a section 44 of the valve needle 26 with a reduced diameter and extends up to the valve seat 24. Between the flange part 30 and the nozzle body 10 there is a distance hg in the illustrated closed position, which corresponds to the total stroke of the valve needle 26. The valve needle 26 is displaced outward in the opening direction by the fuel pressure against the closing spring 28 until the flange part 30 strikes the nozzle body 10. When the valve closes, the closing spring 28 returns the valve needle 26 inward to the closed position shown.

An die Schulter 34 der Ventilnadel 26 schließt sich ein kolbenförmiger Ansatz 46 an, welcher durch den Durchbruch 38 hindurchtritt und in die Kammer 20 ragt. Der Durchmesser des kolbenförmigen Ansatzes 46 entspricht dem Führungsdurchmesser der Ventilnadel 26. Auf den Ansatz 46 ist eine Kappe 48 aufgesetzt, welche einen Boden 50, einen Mantelteil 52 und einen Flanschrand 54 hat. An der Kappe 48 greift eine Rückholfeder 56 an, welche den Mantelteil 52 umgibt und den Flanschrand 54 gegen den Kragen der Hülse 16 drückt.A piston-shaped extension 46 adjoins the shoulder 34 of the valve needle 26, which extends through the opening 38 and projects into the chamber 20. The diameter of the piston-shaped extension 46 corresponds to the guide diameter of the valve needle 26. A cap 48 is placed on the extension 46, which has a bottom 50, a jacket part 52 and a flange edge 54. A return spring 56 engages on the cap 48, which surrounds the jacket part 52 and presses the flange edge 54 against the collar of the sleeve 16.

Im Flanschrand 54 und einem daran anschließenden Bereich des Mantelteils 52 der Kappe 48 sind Querschlitze 58 vorgesehen, durch welche der Kraftstoff immer, auch bei geschlossener Ventilnadel, aus der Kammer 20 in die Kammer 22 übertreten kann. Zwischen der Stirnseite des Ansatzes 46 und dem Boden 50 ist in der Kappe 48 eine Dämpfungskammer 60 gebildet, welche über eine Drosselbohrung 62 im Boden 50 gedrosselt mit dem Strömungsweg des Kraftstoffs verbunden ist. In der dargestellten Schließlage überdeckt der Ansatz 46 die Querschlitze 58 in axialer Richtung um den Weg h" welcher größer als der Gesamthub hg der Ventilnadel 26 ist. Der Weg hi könnte aber auch um einen minimalen Betrag kleiner als der Gesamthub hg sein, so daß sich am Ende eines Öffnungshubes der Ventilnadel 26 noch ein geringer ungedämpfter Teilhub ergibt.In the flange edge 54 and an adjoining region of the jacket part 52 of the cap 48, transverse slots 58 are provided, through which the fuel can always pass from the chamber 20 into the chamber 22, even when the valve needle is closed. A damping chamber 60 is formed in the cap 48 between the end face of the projection 46 and the base 50, which is connected to the flow path of the fuel in a throttled manner via a throttle bore 62 in the base 50. In the illustrated closed position, the projection 46 covers the transverse slots 58 in the axial direction by the path h "which is greater than the total stroke hg of the valve needle 26. However, the path h i could also be smaller by a minimal amount than the total stroke hg, so that there is still a small undamped partial stroke at the end of an opening stroke of the valve needle 26.

Die Drosselbohrung 62 könnte auch teilweise oder ganz durch ein entsprechendes Radialspiel zwischen Kappe 48 und Ansatz 46 ersetzt werden. Der kolbenförmige Ansatz 46 der Ventilnadel 26 und die Kappe 48 bilden gleichzeitig die Mittel zum Dämpfen der Ventilnadelbewegung und eine Zeit-Wegglied, welches den Beginn der Dämpfung abhängig von der Drehzahl und der Größe des Ventilnadelhubes macht. Die Dämpfungswirkung und die Zeit-Wegfunktion werden durch entsprechende Abstimmung der Rückholfeder 56 mit der Drosselbohrung 62 und anderer, das Ein-und Ausströmen des Kraftstoffs in die Dämpfungskammer 60 und aus dieser heraus bestimmender Parameter festgelegt.The throttle bore 62 could also be partially or completely replaced by a corresponding radial play between the cap 48 and the shoulder 46. The piston-shaped extension 46 of the valve needle 26 and the cap 48 simultaneously form the means for damping the valve needle movement and a time-displacement element, which makes the beginning of the damping dependent on the speed and the size of the valve needle stroke. The damping effect and the time-displacement function are determined by appropriate coordination of the return spring 56 with the throttle bore 62 and others, the inflow and outflow of the fuel into the damping chamber 60 and parameters determining it.

Die dargestellte Einspritzdüse arbeitet wie folgt:

  • Durch den ansteigenden Kraftstoffdruck am Beginn eines ersten Einspritzvorganges entsteht sofort eine Druckdifferenz zwischen der Dämpfungskammer 60 und der Kammer 20, weil die Kappe 48 der Bewegung der Ventilnadel 26 nicht folgen kann. Der Druckanstieg in der Dämpfungskammer 60 erfolgt dabei langsamer als in der Kammer 20, so daß die Bewegung der Ventilnadel 26 bei diesem ersten Hub von Anfang an verzögert bzw. gedämpft wird, bis gegebenenfalls die Ventilnadel 26 den Weg hl zurückgelegt hat und die Stirnseite des Ansatzes 46 in den Bereich der Querschlitze 58 gelangt. Von dort ab erfolgt ein minimaler Resthub der Ventilnadel ungedämpft, bis das Flanschteil 30 am Düsenkörper 10 anschlägt. Die gezeigte Stellung der Kappe 48 ist im folgenden als deren erste Endstellung bezeichnet.
The injector shown works as follows:
  • Due to the increasing fuel pressure at the beginning of a first injection process, there is an immediate pressure difference between the damping chamber 60 and the chamber 20 because the cap 48 cannot follow the movement of the valve needle 26. The pressure increase in the damping chamber 60 takes place more slowly than in the chamber 20, so that the movement of the valve needle 26 is delayed or damped from the beginning during this first stroke until the valve needle 26 has traveled the path h 1 and the end face of the Approach 46 reaches the area of the transverse slots 58. From there, there is a minimal residual stroke of the valve needle without damping until the flange part 30 strikes the nozzle body 10. The position of the cap 48 shown is referred to below as its first end position.

Beim beschriebenen Öffnungshub der Ventiinadel 26 wird Kraftstoff durch die Drosselbohrung 62 in die Dämpfungskammer 60 eingesaugt bzw. - gedrückt. Beim folgenden Schließhub wird die Kappe 48 über das Kraftstoffpolster in der Dämpfungskammer 60 mit nach oben in eine im folgenden als zweite Endstellung bezeichnete Stellung verschoben. Dabei setzt die Rückholfeder 56 der wesentlich stärkeren Schließfeder 28 nur einen verhältnismäßig geringen Widerstand entgegen, so daß der Schließhub weitgehend ungedämpft erfolgt. Vom Beginn des Schließhubes ab drückt die Rückholfeder 56 die Kappe 48 gegen das Stirnende des Ansatzes 46 zurück, wobei die in die Dämpfungskammer 60 vorher eingeströmte Kraftstoffmenge aus der Dämpfungskammer 60 wieder verdrängt wird. Das kann wegen der engen Drosselbohrung 62 wiederum nut mit einer gewisen Verzögerung erfolgen. Der Abstand zwischen der ersten und der zweiten Endstellung der Kappe 48 entspricht etwa dem Ventilnadelhub, verringert um einen geringen Rückhub, welchen die Kappe 48 schon während der Schließzeit der Ventilnadel 26 unter dem ständigen Einfluß der Rückholfeder 56 ausführt.During the described opening stroke of the valve needle 26, fuel is sucked in or pressed through the throttle bore 62 into the damping chamber 60. In the following closing stroke, the cap 48 is moved over the fuel cushion in the damping chamber 60 with upward into a position referred to below as the second end position. The return spring 56 opposes the much stronger closing spring 28 only with a relatively low resistance, so that the closing stroke is largely undamped. From the beginning of the closing stroke, the return spring 56 presses the cap 48 back against the front end of the shoulder 46, the amount of fuel that previously flowed into the damping chamber 60 being displaced out of the damping chamber 60. Because of the narrow throttle bore 62, this can in turn only take place with a certain delay. The distance between the first and the second end positions of the cap 48 corresponds approximately to the valve needle stroke, reduced by a small return stroke, which the cap 48 executes during the closing time of the valve needle 26 under the constant influence of the return spring 56.

Die Funktion des aus Kappe 48 samt Dämpfungskammer 60 und Röckholfeder 56 gebildeten Zeit-Weggliedes ist im folgenden anhand der Schaubilder in den Figur 2 bis 4 beschrieben. In diesen Schaubildern sind jeweils der Verlauf des Ventilnadelhubes mit voll zusgezogenen Linien h under der Verlauf der Auslenkung der Kappe 48 mit gestrichelten Linien a über derZeit t dargestellt. In allen drei Schaubildern liegt die in Figur 1 dargestelle Schließlage der Ventilnadel 26 und die erste Endstellung der Kappe 48 in der Zeitachse t.The function of the time travel element formed from the cap 48 together with the damping chamber 60 and the Röckholf spring 56 is described below with reference to the diagrams in FIGS. 2 to 4. In these diagrams, the course of the valve needle stroke with fully drawn lines h and the course of the deflection of the cap 48 are shown with dashed lines a over the time t. In all three diagrams, the closed position of the valve needle 26 shown in FIG. 1 and the first end position of the cap 48 lie in the time axis t.

Zum Zeitpunkt t, (Figur 2) soll der Schließhub der Ventilnadel 26 beginnen, bei welchem die Kappe 48 aus der ersten Endstellung Ei in die zweite Endstellung E2 geschoben wird. Die Kappe 48 legt dabei einen Weg ag zurück, der, wie bereits erwähnt, etwas kleiner als der Gesamthub hg der Ventilnadel 26 ist. Der Schließhub ist zum Zeitpunkt t2 beendet. Von da ab beginnt sich die Kappe 48 unter dem Einfluß der Rückholfeder 56 mit einer vorgegebenen Geschwindigkeit zurückzubewegen, welche im Schaubild sich als Winkel a darstellt.At time t, (FIG. 2), the closing stroke of the valve needle 26 is to begin, at which the cap 48 is pushed from the first end position E i to the second end position E2. The cap 48 travels a path ag which, as already mentioned, is somewhat smaller than the total stroke hg of the valve needle 26. The closing stroke is currently point t 2 ended. From then on, the cap 48 begins to move back under the influence of the return spring 56 at a predetermined speed, which is shown in the diagram as the angle a.

Zum Zeitpunkt t3 beginnt ein neuer Öffnungshub der Ventilnadel 26. Wenn, wie in Figur 2 dargestellt, zum Zeitpunkt t3 die Kappe 48 ihre erste Endstellung noch nicht wieder erreicht hat, wird sie mit annähernd der gleichen Geschwindigkeit wie die Ventilnadel 26 in diese Endstellung zurückgeführt. Sie erreicht dann die erste Endstellung zum Zeitpunkt t4. Von da ab wird die Kappe 48 durch die Schulter 18 an einer weiteren Beweung in Öffnungsrichtung der Ventilnadel 26 festgehalten, wodurch die beschriebenen Dämpfungsmittel wieder wirksam werden. Im Schaubild ist dies dadurch erkennbar, daß der Hubverlaufzum Zeitpunkt t4 einen Knickpunkt K hat. Vom Zeitpunkt t4 wird die Ventilnadel 26 mit gedämpfter, d.h. mit verringerter Geschwindigkeit, in die Hubendstellung überführt, worauf sich das beshriebene Spiel wiederholt.A new opening stroke of valve needle 26 begins at time t 3. If, as shown in FIG. 2, cap 48 has not yet reached its first end position again at time t 3 , it moves into this end position at approximately the same speed as valve needle 26 returned. It then reaches the first end position at time t 4 . From then on, the cap 48 is held by the shoulder 18 against a further movement in the opening direction of the valve needle 26, as a result of which the damping means described become effective again. This can be seen in the diagram in that the stroke curve has a break point K at time t4. From time t 4 the valve needle 26 is transferred to the stroke end position at a damped, ie at a reduced speed, whereupon the game described is repeated.

In den Figuren 3 und 4 ist veranschaulicht, daß sich die erfindungsgemäße Dämpfungseinrichtung den verschiedenen Betriebszuständen der Brennkraftmaschine selbsttätig anpaßt. In Figur 3 läuft die Brennkraftmaschine mit geringer Drehzahl und geringer Belastung, so daß die Kappe 48 ihre erste Endstellung bereits vor Beginn des nächsten Öffnungshubes erreicht. In diesem Fall ist die Dämpfung über dem gesamten Öffnungshub der Ventilnadel 26 wirksam. In Figure 4 ist ein Betriebszustand dargestellt, bei welchem die Brennkraftmaschine mit hoher Drehzahl unter großer Belastung läuft, bei welcher sich auch ein großer Ventilnadelhub einstellt. In diesem Fall beginnt der nächste Öffnungshub, bevor die Kappe 48 in ihre erste Endstellung zurückgelaufen ist. Der Knickpunkt K des Hubverlaufes h der Ventilnadel 26 ist noch weiter gegen das Hubende hin gerückt, als beim Betriebszustand nach Figur 2, so daß auch eine geringerer Teil der Öffnungsbewegung der Ventilnadel 26 gedämpft wird. Die Figur 4 macht auch deutlich, daß der Knickpunkt K um so weiter gegen das Öffnungshubende der Ventilnadel rückt, je schneller die Einspritzvorgänge auf einander folgen und je größer der Ventilnadelhub ist.FIGS. 3 and 4 illustrate that the damping device according to the invention adapts itself automatically to the various operating states of the internal combustion engine. In Figure 3, the internal combustion engine runs at low speed and low load, so that the cap 48 reaches its first end position before the start of the next opening stroke. In this case, the damping is effective over the entire opening stroke of the valve needle 26. Figure 4 shows an operating state in which the internal combustion engine is running at high speed under high load, in which a large valve needle stroke also occurs. In this case, the next opening stroke begins before the cap 48 has returned to its first end position. The break point K of the stroke curve h of the valve needle 26 has moved further towards the end of the stroke than in the operating state according to FIG. 2, so that a smaller part of the opening movement of the valve needle 26 is damped. FIG. 4 also makes it clear that the break point K moves towards the end of the opening of the valve needle, the faster the injection processes follow one another and the greater the valve needle stroke.

Die Kappe 48 zentriert sich auf der Ventilnadel 26 und hat eine ausreichend großes radiales Spiel gegenüber dem Düsenhalter 14, so daß die Ventilnadel 26 klemmfrei arbeiten kann. Die Rückhohlfeder 56 erstreckt sich zum Teil über die Kappe 48 hinweb, so daß bei dieser Ausführung die Mittel zum partiellen Dämpfen des Öffnungshubes der Ventilnadel 26 nur wenig Platz in Achsrichtung der Einspritzdüse benötigen.The cap 48 is centered on the valve needle 26 and has a sufficiently large radial play with respect to the nozzle holder 14 so that the valve needle 26 can work without jamming. The return spring 56 extends in part over the cap 48 so that in this embodiment the means for partially damping the opening stroke of the valve needle 26 take up little space in the axial direction of the injection nozzle.

Claims (2)

1. Fuel injector for internal combustion engines, having a valve needle (26), which is loaded by a closing spring (28), is stressed in the opening direction by the fuel pressure and is coupled to a damping device which has a cylinder (48) and a piston (46), which parts delimit a fuel-filled damping chamber (60), the volume of which' changes during the damped opening stroke due to a relative movement, derived from the movement of the valve needle, between cylinder (48) and piston (46), the fuel being able to enter or leave the damping chamber (60) only via a restricting cross-section (62), which damping device is furthermore provided with a return spring (56) which, from the beginning of the closing stroke, acts on one of the parts (48, 46) delimiting the damping chamber (60) and moves this part back towards its original position counter to the flow resistance in the restricting cross-section (62), and in which damping device (46, 48, 56) the return spring (56) and the restricting cross-section (62) are matched to one another in such a way that, above a certain speed and/or injection quantity (needle stroke) a delayed activation of the damping device occurs by virtue of the fact that, at the beginning of the subsequent opening stroke of the valve needle (26), the part (48, 46) acted upon by the return spring (56) has only travelled part of its possible return path into the original position and that the part connected to the valve needle (26) takes the part acted upon by the return spring, together with the fuel cushion enclosed in the damping chamber, freely along with it as far as the original position, whereupon damping starts.
2. Injector according to Claim 1, having a valve needle opening in the direction of flow of the fuel, characterized in that the piston (46) of the damping device is formed by the feed-side end portion of the valve needle (26) itself, a cap (48) pushed onto this end portion (46) serves as a cylinder and the return spring (56) acts on the cap (48), to which a stop (18) fixed to the housing is allocated.
EP83105257A 1982-06-07 1983-05-27 Fuel injector for an internal-combustion engine Expired - Lifetime EP0096312B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3221442 1982-06-07
DE19823221442 DE3221442A1 (en) 1982-06-07 1982-06-07 FUEL INJECTION NOZZLE FOR INTERNAL COMBUSTION ENGINES

Publications (2)

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EP0096312A1 EP0096312A1 (en) 1983-12-21
EP0096312B1 true EP0096312B1 (en) 1990-12-19

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EP83105257A Expired - Lifetime EP0096312B1 (en) 1982-06-07 1983-05-27 Fuel injector for an internal-combustion engine

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US (1) US4747545A (en)
EP (1) EP0096312B1 (en)
JP (1) JPS593165A (en)
DE (2) DE3221442A1 (en)

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DE3405161A1 (en) * 1984-02-14 1985-08-22 Robert Bosch Gmbh, 7000 Stuttgart FUEL INJECTION NOZZLE FOR INTERNAL COMBUSTION ENGINES
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Also Published As

Publication number Publication date
JPH0429873B2 (en) 1992-05-20
EP0096312A1 (en) 1983-12-21
JPS593165A (en) 1984-01-09
DE3221442A1 (en) 1983-12-08
DE3382065D1 (en) 1991-01-31
US4747545A (en) 1988-05-31

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