EP0656472B1 - Fuel injection device for pilot and main injection - Google Patents

Fuel injection device for pilot and main injection Download PDF

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Publication number
EP0656472B1
EP0656472B1 EP94117904A EP94117904A EP0656472B1 EP 0656472 B1 EP0656472 B1 EP 0656472B1 EP 94117904 A EP94117904 A EP 94117904A EP 94117904 A EP94117904 A EP 94117904A EP 0656472 B1 EP0656472 B1 EP 0656472B1
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EP
European Patent Office
Prior art keywords
injection
hollow piston
pressure chamber
pressure
injection device
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.)
Expired - Lifetime
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EP94117904A
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German (de)
French (fr)
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EP0656472A1 (en
Inventor
Erwin Ditschun
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Volkswagen AG
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Volkswagen AG
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Publication of EP0656472A1 publication Critical patent/EP0656472A1/en
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Classifications

    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02MSUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M45/00Fuel-injection apparatus characterised by having a cyclic delivery of specific time/pressure or time/quantity relationship
    • F02M45/02Fuel-injection apparatus characterised by having a cyclic delivery of specific time/pressure or time/quantity relationship with each cyclic delivery being separated into two or more parts
    • F02M45/04Fuel-injection apparatus characterised by having a cyclic delivery of specific time/pressure or time/quantity relationship with each cyclic delivery being separated into two or more parts with a small initial part, e.g. initial part for partial load and initial and main part for full load
    • F02M45/06Pumps peculiar thereto
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02MSUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M45/00Fuel-injection apparatus characterised by having a cyclic delivery of specific time/pressure or time/quantity relationship
    • F02M45/02Fuel-injection apparatus characterised by having a cyclic delivery of specific time/pressure or time/quantity relationship with each cyclic delivery being separated into two or more parts
    • F02M45/04Fuel-injection apparatus characterised by having a cyclic delivery of specific time/pressure or time/quantity relationship with each cyclic delivery being separated into two or more parts with a small initial part, e.g. initial part for partial load and initial and main part for full load
    • F02M45/08Injectors peculiar thereto
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02MSUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M57/00Fuel-injectors combined or associated with other devices
    • F02M57/02Injectors structurally combined with fuel-injection pumps
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02MSUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M59/00Pumps specially adapted for fuel-injection and not provided for in groups F02M39/00 -F02M57/00, e.g. rotary cylinder-block type of pumps
    • F02M59/20Varying fuel delivery in quantity or timing
    • F02M59/36Varying fuel delivery in quantity or timing by variably-timed valves controlling fuel passages to pumping elements or overflow passages
    • F02M59/366Valves being actuated electrically

Definitions

  • the invention relates to an injection device, in particular a pump nozzle, which is set up for pre-injection and main injection of fuel, according to the preamble of patent claim 1.
  • the pressure chamber associated with the pre-injection is incorporated into the outer circumference of the hollow piston and is constantly in flow communication with the pressure channel leading to the nozzle needle, which is built into the housing of the pump nozzle.
  • a trailing edge of the hollow piston opens a flow connection between the pressure chamber and the pressure chamber, which results in a Pressure relief of the pressure chamber takes place, which results in a pressure collapse in the pressure line causing the return of the nozzle needle to its closed position.
  • a spring-loaded valve piston is let into the hollow piston, which is moved into an open position at low pressure in the pressure chamber and then releases a flow connection to the pressure chamber through an opening in the wall of the hollow piston; the fuel is supplied from the nozzle spring chamber.
  • the known pump nozzle has the particular disadvantage that the pre-injection is ended by establishing a relatively long outflow path between the pressure chamber and the pressure chamber.
  • the pressure drop in the pressure line that triggers the renewed closing movement of the nozzle needle under the action of its closing spring is therefore subject to a large number of variable influences, such as temperature, dynamic influences and speed of the machine.
  • the invention has for its object to provide a generic injection device in which the exact adherence to the injection parameters (injection time and quantity) is ensured with simple means and easy to assemble.
  • the invention offers the advantage of very precise adherence to specified values for the injection time and the injection quantity.
  • the end of the pre-injection is not triggered by a long-term control process that takes time, but by placing the hollow piston on a fixed counterstop. This immediately ends a further reduction in the volume of the pressure chamber for the pre-injection, so that due to the outflow of the pressure standing fuel is immediately reduced by the still open nozzle, the fuel pressure causing the opening of the nozzle.
  • This pressure reduction is not complete, but is limited to a value given by the respective force of the closing spring, so that the main injection pressure does not have to be built up from zero.
  • FIGS. 1 and 2 show longitudinal sections in different operating states and whose FIG. 3 represent the cross section III-III, while FIG. 4 likewise shows another possible connection between the hollow piston and spring plate in a longitudinal section.
  • FIGS. 1 to 3 in particular FIG. 1, in which the position of the various components of the pump nozzle that are of interest here is shown during the base circle phase of a cam serving to actuate them, there are in the through bore 1 in the housing part 2 of the furthermore, the housing parts 3 and 4 having the housing of the pump nozzle in the direction of the longitudinal axis 5, one behind the other, the high-pressure piston 6, the pressure chamber 7 and the hollow piston 8.
  • the bore 1 has the same diameter throughout, which in terms of Manufacturing and finishing the surface of the bore 1 is optimal.
  • a guide 9 is provided in the housing part 3 for the spring plate 10, which is a quite compact component, which has larger transverse dimensions than the bore 1 in the housing part 2.
  • the spring plate 10 is supported under the action of the closing spring 11 for the nozzle needle of the nozzle part of the pump nozzle indicated in FIG. 2 at 11a and accommodated by the housing part 4 on the lower end face 12 of the housing part, which is to be designated as a stop in FIGS. 1 and 2 2 in the rest position shown in Figure 1.
  • the plunger 13 which may be in one piece with the spring plate 10 and which has cylindrical projections 13a, 13b on both sides.
  • the length of the hollow piston 8 is dimensioned in relation to the operating state shown in FIG. 1 so that there is a gap or distance a between the mutually facing end faces of the hollow piston 8 and the spring plate 10 is preserved. It should already be pointed out that this distance a in conjunction with the radius b of the surface of the pressure chamber 15 determines the amount of the pre-injected fuel (pre-injection amount).
  • the ratio of the end face 17 of the hollow piston 8 closed at the end to the pressure space 7 to this area with the dimension b ultimately brings about a desired pressure increase in the pressure channel 18 during the pre-injection, which leads in the usual way to the nozzle needle 11a and there opens into a pressure chamber in such a way that the fuel pressure, if it exceeds a minimum value specified by the choice of the strength of the closing spring 11, lifts the nozzle needle in FIGS. 1 and 2 upwards from its seat and thus the nozzle of the pump nozzle for the pilot injection opens.
  • the housing part 3 which slidably receives it is also designed to be inexpensive to manufacture.
  • the guide 9 can also be manufactured continuously or - before assembly of the housing - from the top side in FIG. 1.
  • the components 8, 10, 13 and 14 can be assembled into a preassembly unit before they are inserted into the housing, which is then practically inserted together with the high-pressure piston 6 into the bore 1 of the upper housing part 2, after which the housing part 3 is threaded onto the spring plate 10 and connected to the housing part 2, but in a predetermined orientation.
  • a large number of channels can be seen in the housing parts 2 and 3, which serve to supply and remove fuel and which run essentially parallel to the longitudinal axis 5. This is also illustrated by the view in FIG. 3.
  • the relatively long design of these channels offers advantages with regard to the cooling of the pump nozzle during operation and with regard to the position of the connections of the pump nozzle for fuel supply and removal.
  • the fuel supply to the pump nozzle is indicated at 23a.
  • the transverse bore 28 of the fuel discharge channel 29 opens into the upper region of the pressure chamber 7 which is released in this operating state leads the middle housing part 3 incorporated fuel drain 30 from the pump nozzle. Fuel can be supplied and removed accordingly from a holder of the pump nozzle, and effective cooling of the nozzle by the fuel is also ensured.
  • the actual spring plate is represented by part 40, which in this exemplary embodiment is made in one piece with the plunger, again designated by 13.
  • the connection between the spring plate and the hollow piston 8 is made via the sleeve-shaped part 42 which forms the second component of the spring plate and is not necessarily connected to part 40, again while maintaining the gap a, whereby this Solution offers the advantage of adjustability of this gap.
  • the junction 18a of the pressure channel 18 is chosen in relation to the position of transverse bores in a continuation of the pressure chamber 15 such that, according to arrow 29 in FIG. 2, the pressure chamber 7 for supplying fuel to the pressure chamber during a relatively short phase of the upward and downward movements of the hollow piston 8 15 is connected to this.
  • the downward movement of the hollow piston 8 until the distance a is eliminated has the result of a reduction in the axial extent of the pressure chamber 15 and thus an increase in the pressure in it, resulting in as an increase in pressure in the pressure channel 18 and thus in an increase of the opening force acting on the nozzle needle:
  • the nozzle needle 11a is lifted from its seat to a value given by the design of the closing spring 11 until this pressure is released, ie fuel is pre-injected into an intake manifold or a combustion chamber of the internal combustion engine.
  • Another advantage of the invention is the fact that the configuration of the cam for driving the high-pressure piston 6 is facilitated due to the pressure or force transmission during the pre-injection (choice of dimension b and the size of the surface 17). In any case, the cam area of maximum speed remains for the main injection, since only a small pressure or a small pressure increase in the pressure chamber 7 is required for the pre-injection.
  • the invention offers not only fundamental advantages with regard to the mode of operation, in particular with regard to the precise ones Adherence to the pre-injection quantity and time, but also with regard to cooling and thus exact compliance with dimensions (gap dimensions) important for the injection parameters as well as with regard to simple production.
  • the measures according to the invention in the context of the pre-injection can advantageously also be used with a normal injection nozzle (possibly without an attached electromagnetic valve), which is not combined with a pump.

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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

Die Erfindung betrifft eine zur Vor- und Haupteinspritzung von Kraftstoff eingerichtete Einspritzvorrichtung, insbesondere Pumpedüse, gemäß dem Oberbegriff des Patentanspruchs 1.The invention relates to an injection device, in particular a pump nozzle, which is set up for pre-injection and main injection of fuel, according to the preamble of patent claim 1.

Bekanntlich werden an derartige zur Kraftstoffspeisung von Brennkraftmaschinen dienende Einspritzvorrichtungen hohe Anforderungen hinsichtlich einer zeit- und mengengenauen Vor- und Haupteinspritzung von Kraftstoff gestellt. Bei einer aus der DE-OS 36 29 754, F02M 45/08, bekannten gattungsgemäßen Pumpedüse mit den Merkmalen des Oberbegriffs des Hauptanspruchs ist die der Voreinspritzung zugeordnete Druckkammer in den Außenumfang des Hohlkolbens eingearbeitet und steht dauernd in Strömungsverbindung mit dem zur Düsennadel führenden Druckkanal, der in das Gehäuse der Pumpedüse eingearbeitet ist. Zur Beendigung der Voreinspritzung, d. h. dann, wenn der Hohlkolben beispielsweise durch eine von einem Nocken auf den Hochdruckkolben ausgeübte und über den Druckraum übertragene Kraft seinen vorgegebenen Voreinspritzhub zurückgelegt hat, gibt eine Abströmkante des Hohlkolbens eine Strömungsverbindung zwischen dem Druckraum und der Druckkammer frei, wodurch eine Druckentlastung der Druckkammer erfolgt, die einen die Rückkehr der Düsennadel in ihre Schließstellung verursachenden Druckzusammenbruch in der Druckleitung zur Folge hat. Zur erneuten Befüllung der der Voreinspritzung zugeordneten Druckkammer ist in den Hohlkolben ein federbelasteter Ventilkolben eingelassen, der bei niedrigem Druck im Druckraum in eine Öffnungsstellung bewegt wird und dann eine Strömungsverbindung zu der Druckkammer durch eine Durchbrechung der Wand des Hohlkolbens freigibt; die Kraftstoffzufuhr erfolgt dort vom Düsenfederraum her.As is known, high demands are placed on such injection devices serving for fuel feeding of internal combustion engines with regard to a precise and precise pre-injection and main injection of fuel. In a generic pump nozzle known from DE-OS 36 29 754, F02M 45/08, with the features of the preamble of the main claim, the pressure chamber associated with the pre-injection is incorporated into the outer circumference of the hollow piston and is constantly in flow communication with the pressure channel leading to the nozzle needle, which is built into the housing of the pump nozzle. To terminate the pre-injection, i.e. when the hollow piston has traveled its predetermined pre-injection stroke, for example due to a force exerted by a cam on the high-pressure piston and transmitted via the pressure chamber, a trailing edge of the hollow piston opens a flow connection between the pressure chamber and the pressure chamber, which results in a Pressure relief of the pressure chamber takes place, which results in a pressure collapse in the pressure line causing the return of the nozzle needle to its closed position. For refilling the pre-injection assigned pressure chamber, a spring-loaded valve piston is let into the hollow piston, which is moved into an open position at low pressure in the pressure chamber and then releases a flow connection to the pressure chamber through an opening in the wall of the hollow piston; the fuel is supplied from the nozzle spring chamber.

Die bekannte Pumpedüse besitzt vor allem den Nachteil, daß die Voreinspritzung beendet wird durch Herstellung eines relativ langen Abströmweges zwischen Druckkammer und Druckraum. Damit unterliegt der die erneute Schließbewegung der Düsennadel unter der Wirkung ihrer Schließfeder auslösende Druckabfall in der Druckleitung einer Vielzahl von veränderlichen Einflüssen, wie Temperatur, dynamischen Einflüssen und Drehzahl der Maschine.The known pump nozzle has the particular disadvantage that the pre-injection is ended by establishing a relatively long outflow path between the pressure chamber and the pressure chamber. The pressure drop in the pressure line that triggers the renewed closing movement of the nozzle needle under the action of its closing spring is therefore subject to a large number of variable influences, such as temperature, dynamic influences and speed of the machine.

Der Erfindung liegt die Aufgabe zugrunde, eine gattungsgemäße Einspritzvorrichtung zu schaffen, bei der mit einfachen Mitteln und montagefreundlicher Bauweise die genaue Einhaltung der Einspritzparameter (Einspritzzeit und -menge) sichergestellt ist.The invention has for its object to provide a generic injection device in which the exact adherence to the injection parameters (injection time and quantity) is ensured with simple means and easy to assemble.

Die erfindungsgemäße Lösung dieser Aufgabe besteht in den kennzeichnenden Merkmalen des Hauptanspruchs, vorteilhafte Ausbildungen der Erfindung beschreiben die Unteransprüche.The achievement of this task consists in the characterizing features of the main claim, advantageous embodiments of the invention describe the subclaims.

Insbesondere dann, wenn durch Heranziehung einer Kraftstoffdurchströmung der Einspritzvorrichtung und entsprechende Anordnung und Ausbildung der Kraftstoffkanäle für eine dauernde Kühlung der Vorrichtung gesorgt ist, bietet die Erfindung den Vorteil einer sehr genauen Einhaltung vorgegebener Werte für Einspritzzeitpunkt und Einspritzmenge. In Abweichung von dem diskutierten Stand der Technik wird das Ende der Voreinspritzung nicht durch einen über lange Wege erfolgenden, Zeit benötigenden Absteuervorgang ausgelöst, sondern durch Auflage der Hohlkolbens auf einem festen Gegenanschlag. Damit wird sofort eine weitere Verringerung des Volumens der Druckkammer für die Voreinspritzung beendet, so daß infolge Abflusses des unter Drucks stehenden Kraftstoffs durch die noch geöffnete Düse unmittelbar der das Öffnen der Düse bewirkende Kraftstoffdruck abgebaut wird. Dieser Druckabbau ist nicht vollständig, sondern auf einen durch die jeweilige Kraft der Schließfeder gegebenen Wert begrenzt, so daß der Haupteinspritzdruck nicht von Null aus aufgebaut werden muß.In particular, if the device is provided with a permanent cooling of the device by using a fuel flow through the injection device and the corresponding arrangement and design of the fuel channels, the invention offers the advantage of very precise adherence to specified values for the injection time and the injection quantity. In a departure from the state of the art discussed, the end of the pre-injection is not triggered by a long-term control process that takes time, but by placing the hollow piston on a fixed counterstop. This immediately ends a further reduction in the volume of the pressure chamber for the pre-injection, so that due to the outflow of the pressure standing fuel is immediately reduced by the still open nozzle, the fuel pressure causing the opening of the nozzle. This pressure reduction is not complete, but is limited to a value given by the respective force of the closing spring, so that the main injection pressure does not have to be built up from zero.

Dagegen kann, wie in den Ansprüchen 11 und 12 dargelegt, die Freigabe eines Strömungsquerschnitts durch den Hohlkolben, wenn er sich in einer bestimmten Position befindet, dazu ausgenutzt werden, eine insofern unkritische Verbindung zwischen Druckraum und Druckkammer zwecks erneuten Druckaufbaus in der Druckkammer freizugeben.In contrast, as set out in claims 11 and 12, the release of a flow cross-section through the hollow piston, when it is in a certain position, can be used to release an uncritical connection between the pressure chamber and pressure chamber for the purpose of renewed pressure build-up in the pressure chamber.

Die weitere Hubbewegung des Hohlkolbens bis zum Wirksamwerden eines seine Längsbewegung verhindernden gehäusefesten Anschlags hat keinen erneuten Druckaufbau in der Druckkammer und in der Druckleitung zur Düse zur Folge, so daß während dieses zweiten Hubbereichs keine Einspritzung erfolgt. Da nunmehr bei weiterer Längsbewegung des Hochdruckkolbens beispielsweise unter dem Einfluß eines Nockens der Hohlkolben seine Lage nicht ändert, wird der Druck im Druckraum erhöht, und zwar auf einen Wert, der angesichts der durch die Längsbewegung des Hohlkolbens zusammengedrückten Schließfeder für die Düsennadel höher ist als der Druckwert zur Voreinspritzung. Schließlich übersteigt die vom Kraftstoffdruck auf die Düsennadel ausgeübte Öffnungskraft die Schließkraft der zusammengedrückten Schließfeder, und die Haupteinspritzung beginnt; sie wird beendet durch Öffnen des elektromagnetischen Ventils, das zur Druckentlastung des Druckraums und damit der Druckleitung führt.The further stroke movement of the hollow piston until a stop fixed to the housing which prevents its longitudinal movement becomes effective does not result in a renewed build-up of pressure in the pressure chamber and in the pressure line to the nozzle, so that no injection takes place during this second stroke range. Since the position of the hollow piston does not change during further longitudinal movement of the high-pressure piston, for example under the influence of a cam, the pressure in the pressure chamber is increased to a value which is higher than that in view of the closing spring for the nozzle needle compressed by the longitudinal movement of the hollow piston Pressure value for pre-injection. Finally, the opening force exerted by the fuel pressure on the nozzle needle exceeds the closing force of the compressed closing spring, and the main injection begins; it is ended by opening the electromagnetic valve, which leads to pressure relief in the pressure chamber and thus in the pressure line.

Zwei Ausführungsbeispiele erfindungsgemäßer Pumpedüsen werden im folgenden anhand der Zeichnung erläutert, deren Figuren 1 und 2 Längsschnitte in verschiedenen Betriebszuständen und deren Figur 3 den Querschnitt III - III wiedergeben, während Figur 4 ebenfalls in einem Längsschnitt eine andere mögliche Verbindung zwischen Hohlkolben und Federteller zeigt.Two exemplary embodiments of pump nozzles according to the invention are explained below with reference to the drawing, the FIGS. 1 and 2 of which show longitudinal sections in different operating states and whose FIG. 3 represent the cross section III-III, while FIG. 4 likewise shows another possible connection between the hollow piston and spring plate in a longitudinal section.

Betrachtet man nun zunächst die Figuren 1 bis 3, und zwar insbesondere Figur 1, in der die Lage der verschiedenen hier teressierenden Bestandteile der Pumpedüse während der Grundkreisphase eines zu ihrer Betätigung dienenden Nockens dargestellt ist, so finden sich in der Durchgangsbohrung 1 im Gehäuseteil 2 des ferner die Gehäuseteile 3 und 4 aufweisenden Gehäuses der Pumpedüse in Richtung der Längsachse 5 hintereinander der Hochdruckkolben 6, der Druckraum 7 und der Hohlkolben 8. Infolge Verwendung gleicher Durchmesser für die Teile 6 und 8 besitzt die Bohrung 1 einen durchgehend gleichen Durchmesser, was hinsichtlich der Fertigung und der Feinbearbeitung der Oberfläche der Bohrung 1 optimal ist. Dagegen ist in dem Gehäuseteil 3 eine Führung 9 für den ein hier recht kompaktes Bauteil darstellenden Federteller 10 vorgesehen, die größere Querabmessungen besitzt als die Bohrung 1 in dem Gehäuseteil 2. In vorteilhafter Weise braucht nur die Führung im Gehäuseteil 2 dichtend ausgeführt zu sein. Demgemäß stützt sich der Federteller 10 unter der Wirkung der Schließfeder 11 für die in Figur 2 bei 11a angedeutete, von dem Gehäuseteil 4 aufgenommene Düsennadel des Düsenteils der Pumpedüse an der demgemäß als Anschlag zu bezeichnenden, in den Figuren 1 und 2 unteren Stirnfläche 12 des Gehäuseteils 2 in der in Figur 1 dargestellten Ruhelage ab.If one now considers FIGS. 1 to 3, in particular FIG. 1, in which the position of the various components of the pump nozzle that are of interest here is shown during the base circle phase of a cam serving to actuate them, there are in the through bore 1 in the housing part 2 of the furthermore, the housing parts 3 and 4 having the housing of the pump nozzle in the direction of the longitudinal axis 5, one behind the other, the high-pressure piston 6, the pressure chamber 7 and the hollow piston 8. As a result of using the same diameter for the parts 6 and 8, the bore 1 has the same diameter throughout, which in terms of Manufacturing and finishing the surface of the bore 1 is optimal. In contrast, a guide 9 is provided in the housing part 3 for the spring plate 10, which is a quite compact component, which has larger transverse dimensions than the bore 1 in the housing part 2. Advantageously, only the guide in the housing part 2 needs to be made sealing. Accordingly, the spring plate 10 is supported under the action of the closing spring 11 for the nozzle needle of the nozzle part of the pump nozzle indicated in FIG. 2 at 11a and accommodated by the housing part 4 on the lower end face 12 of the housing part, which is to be designated as a stop in FIGS. 1 and 2 2 in the rest position shown in Figure 1.

Im Hohlkolben 8 erkennt man den - ggf. mit dem Federteller 10 einstückigen - Tauchkolben 13, welcher beidseitig zylindrische Ansätze 13a, 13b aufweist. Die koaxial zum oberen Ansatz 13a angeordnete Feder 14 presst, sich an der Innenfläche 16 des Hohlkolbens 8 abstützend, den unteren Ansatz 13b auf den Federteller 10. Wichtig ist, daß zwischen der obersten Fläche des Ansatzes 13a und der Innenfläche 16 des topfähnlichen Hohlkolbens 8 ein durch die Feder 14 überbrückter Abstand vorliegt.In the hollow piston 8 one recognizes the plunger 13, which may be in one piece with the spring plate 10 and which has cylindrical projections 13a, 13b on both sides. The spring 14, which is arranged coaxially to the upper attachment 13a, presses against the inner surface 16 of the hollow piston 8 and presses the lower attachment 13b onto the spring plate 10. It is important that a between the uppermost surface of the attachment 13a and the inner surface 16 of the cup-like hollow piston 8 there is a distance bridged by the spring 14.

Wichtig ist ferner, daß der Hohlkolben 8 in seiner Länge in Bezug auf den in Figur 1 dargestellten Betriebszustand so dimensioniert ist, daß zwischen den einander zugekehrten Stirnflächen von Hohlkolben 8 und Federteller 10 ein Spalt oder Abstand a gewahrt ist. Bereits jetzt sei darauf hingewiesen, daß dieser Abstand a in Verbindung mit dem Radius b der Fläche der Druckkammer 15 die Menge des voreingespritzten Kraftstoffs (Voreinspritzmenge) bestimmt. Weiterhin sei bereits jetzt darauf hingewiesen, daß das Verhältnis der den Druckraum 7 begrenzenden Stirnfläche 17 des stirnseitig geschlossenen Hohlkolbens 8 zu dieser Fläche mit dem Maß b eine erwünschte Druckerhöhung letztlich in dem Druckkanal 18 während der Voreinspritzung bewirkt, der in üblicher Weise zur Düsennadel 11a führt und dort so in einen Druckraum einmündet, daß der Kraftstoffdruck, wenn er einen durch die Wahl der Stärke der Schließfeder 11 vorgegebenen Mindestwert übersteigt, die Düsennadel in den Figuren 1 und 2 in Richtung nach oben von ihrem Sitz abhebt und damit die Düse der Pumpedüse für die Voreinspritzung öffnet.It is also important that the length of the hollow piston 8 is dimensioned in relation to the operating state shown in FIG. 1 so that there is a gap or distance a between the mutually facing end faces of the hollow piston 8 and the spring plate 10 is preserved. It should already be pointed out that this distance a in conjunction with the radius b of the surface of the pressure chamber 15 determines the amount of the pre-injected fuel (pre-injection amount). Furthermore, it should already be pointed out that the ratio of the end face 17 of the hollow piston 8 closed at the end to the pressure space 7 to this area with the dimension b ultimately brings about a desired pressure increase in the pressure channel 18 during the pre-injection, which leads in the usual way to the nozzle needle 11a and there opens into a pressure chamber in such a way that the fuel pressure, if it exceeds a minimum value specified by the choice of the strength of the closing spring 11, lifts the nozzle needle in FIGS. 1 and 2 upwards from its seat and thus the nozzle of the pump nozzle for the pilot injection opens.

Betrachtet man nun nochmals die Verhältnisse im Bereich des Federtellers 10, so ist auch der ihn verschiebbar aufnehmende Gehäuseteil 3 fertigungsgünstig gestaltet. Die Führung 9 kann vom Prinzip her ebenfalls durchgehend oder aber - vor dem Zusammenbau des Gehäuses - von der in Figur 1 oberen Seite her gefertigt werden. Was nun die Krafteinleitung in den Federteller 10 zum Zwecke der Ausführung von Längsbewegungen in Richtung der Längsachse 5 anbelangt, so erfolgen Bewegungen entgegen der Kraft der Schließfeder 11, also in den Figuren 1 und 2 in Richtung nach unten, bei durch einen Nocken veranlaßten Längsbewegungen des Hochdruckkolbens 6 in dieser Richtung, die über den Druck im Druckraum 7 und den Hohlkolben 8 dann auf den Federteller 10 übertragen werden, wenn sich der Hohlkolben 8 entgegen der Wirkung der Druckfeder 14 in der Druckkammer 15 unter Überwindung des Abstands a unmittelbar auf der zugekehrten Stirnfläche des Federtellers 10 abgestützt hat. Bewegungen in entgegengesetzter Richtung können die beiden Bauteile 8 und 10 nach Wiederherstellung des Abstands a zwischen ihnen nur gemeinsam ausführen, da der Federteller 10 einen in Figur 1 oberen Bereich 19 mit einer zentrischen Ausnehmung 20 aufweist, deren Begrenzungswand mit dem umlaufenden Hinterschnitt 21 versehen ist, der von hakenförmigen Fortsätzen 22 am Hohlkolben 8 hintergriffen ist (Fangverbindung). Zur Demontage sind Ausnehmungen 23 in der Wand des zylindrischen Federtellerbereichs 19 vorgesehen, die die Einführung eines Werkzeugs zum Zurückdrücken der Haken in Richtung auf die Längsachse 5 ermöglichen.If one now looks again at the conditions in the area of the spring plate 10, the housing part 3 which slidably receives it is also designed to be inexpensive to manufacture. In principle, the guide 9 can also be manufactured continuously or - before assembly of the housing - from the top side in FIG. 1. With regard to the introduction of force into the spring plate 10 for the purpose of executing longitudinal movements in the direction of the longitudinal axis 5, movements take place against the force of the closing spring 11, that is to say downwards in FIGS. 1 and 2, in the event of longitudinal movements of the cam caused by a cam High-pressure piston 6 in this direction, which are then transferred to the spring plate 10 via the pressure in the pressure chamber 7 and the hollow piston 8 when the hollow piston 8 is located directly against the action of the compression spring 14 in the pressure chamber 15, overcoming the distance a, on the facing end face has supported the spring plate 10. Movements in the opposite direction can only be carried out by the two components 8 and 10 after restoring the distance a between them, since the spring plate 10 has an area 19 in FIG. 1 with a central recess 20, the boundary wall of which has the circumferential undercut 21 which is engaged by hook-shaped extensions 22 on the hollow piston 8 (catch connection). For dismantling, recesses 23 are provided in the wall of the cylindrical spring plate area 19, which allow the introduction of a tool for pushing back the hooks in the direction of the longitudinal axis 5.

Bereits jetzt wird erkennbar, daß die Bestandteile 8, 10, 13 und 14 vor ihrem Einsetzen in das Gehäuse zu einer Vormontageeinheit zusammengebaut werden können, die dann praktisch zusammen mit dem Hochdruckkolben 6 in die Bohrung 1 des oberen Gehäuseteils 2 eingeführt wird, wonach der Gehäuseteil 3 auf den Federteller 10 aufgefädelt und mit dem Gehäuseteil 2 verbunden wird, allerdings in einer vorgegebenen Ausrichtung. Man erkennt nämlich eine Vielzahl von Kanälen in den Gehäuseteilen 2 und 3, die der Zuund Abfuhr von Kraftstoff dienen und die im wesentlichen parallel zur Längsachse 5 verlaufen. Dies veranschaulicht auch die Ansicht der Figur 3. Die relativ lange Ausbildung dieser Kanäle bietet Vorteile hinsichtlich der Kühlung der Pumpedüse im Betrieb sowie hinsichtlich der Lage der Anschlüsse der Pumpedüse für Kraftstoffzu- und -abfuhr. Die Kraftstoffzufuhr zur Pumpedüse ist bei 23a angedeutet. Sie führt über den Kanal 24, der mit Querbohrungen versehen ist, sowohl in den die Schließfeder 11 aufnehmenden Raum 25 als auch in den Figuren 1 und 2 in Richtung nach oben über die Querbohrung 26 in den in der in Figur 1 angenommenen Ruhelage freigegebenen unteren Bereich des Druckraums 1. Im Zuge des Querkanals 26 erkennt man das tromagnetventil 27, das von einem Steuergerät her während der Einspritzvorgänge im den Kraftstoffabfluß aus dem Druckraum 7 sperrenden Sinne betätigt wird; dieser Zustand ist in Figur 1 dargestellt.It can already be seen that the components 8, 10, 13 and 14 can be assembled into a preassembly unit before they are inserted into the housing, which is then practically inserted together with the high-pressure piston 6 into the bore 1 of the upper housing part 2, after which the housing part 3 is threaded onto the spring plate 10 and connected to the housing part 2, but in a predetermined orientation. A large number of channels can be seen in the housing parts 2 and 3, which serve to supply and remove fuel and which run essentially parallel to the longitudinal axis 5. This is also illustrated by the view in FIG. 3. The relatively long design of these channels offers advantages with regard to the cooling of the pump nozzle during operation and with regard to the position of the connections of the pump nozzle for fuel supply and removal. The fuel supply to the pump nozzle is indicated at 23a. It leads via the channel 24, which is provided with transverse bores, both in the space 25 receiving the closing spring 11 and in FIGS. 1 and 2 in an upward direction via the transverse bore 26 in the lower region released in the rest position assumed in FIG of the pressure chamber 1. In the course of the transverse channel 26 one recognizes the solenoid valve 27, which is actuated by a control unit during the injection processes in the sense that blocks the fuel flow from the pressure chamber 7; this state is shown in FIG. 1.

Zur Erzielung einer praktisch dauernden Kraftstoffdurchströmung des Druckraums 7 und damit auch einer laufenden Abfuhr von Gas- und Dampfblasen aus dem Kraftstoff mündet in den in diesem Betriebszustand freigegebenen oberen Bereich des Druckraums 7 die Querbohrung 28 des Kraftstoffabfuhrkanals 29 ein, der zu dem in den mittleren Gehäuseteil 3 eingearbeiteten Kraftstoffabfluß 30 aus der Pumpedüse führt. Kraftstoffzu- und -abführung können demgemäß von einer Halterung der Pumpedüse her erfolgen, auch ist eine wirksame Kühlung der Düse durch den Kraftstoff sichergestellt.In order to achieve a practically continuous flow of fuel through the pressure chamber 7 and thus also a continuous removal of gas and vapor bubbles from the fuel, the transverse bore 28 of the fuel discharge channel 29 opens into the upper region of the pressure chamber 7 which is released in this operating state leads the middle housing part 3 incorporated fuel drain 30 from the pump nozzle. Fuel can be supplied and removed accordingly from a holder of the pump nozzle, and effective cooling of the nozzle by the fuel is also ensured.

Ehe auf die Arbeitsweise der dargestellten Pumpedüse eingegangen wird, sei darauf hingewiesen, daß verständlicherweise konstruktive Abänderungen möglich sind. So ist es möglich, die Feder 14 nicht, wie dargestellt, als Wendelfeder, sondern als Elastomerfeder auszuführen, die zugleich Dichtfunktionen übernimmt und die hier durch die hakenförmigen Fortsätze 22 in Verbindung mit dem Hinterschnitt 21 gegebene Fangverbindung zwischen Hohlkolben 8 und Federteller 10 ersetzt. Auch kann der Federteller 10 zweiteilig ausgeführt sein. Eine entsprechende Ausführung ist in Figur 4 dargestellt:Before going into the mode of operation of the pump nozzle shown, it should be pointed out that understandable design changes are possible. It is thus possible, as shown, not to design the spring 14 as a helical spring, but rather as an elastomer spring, which at the same time performs sealing functions and replaces the catch connection between the hollow piston 8 and the spring plate 10 given here by the hook-shaped extensions 22 in connection with the undercut 21. The spring plate 10 can also be made in two parts. A corresponding embodiment is shown in Figure 4:

Der eigentliche Federteller wird durch das Teil 40 dargestellt, das in diesem Ausführungsbeispiel einteilig mit dem wiederum mit 13 bezeichneten Tauchkolben ausgeführt ist. Mittels der den Tauchkolben 13 mit Spiel umschließenden Hohlschraube 41 erfolgt über das den zweiten Bestandteil des Federtellers bildende, mit Teil 40 nicht notwendigerweise verbundene hülsenförmige Teil 42 die Herstellung einer Verbindung zwischen Federteller und Hohlkolben 8, und zwar wiederum unter Wahrung des Spalts a, wobei diese Lösung den Vorteil der Einstellbarkeit dieses Spalts bietet.The actual spring plate is represented by part 40, which in this exemplary embodiment is made in one piece with the plunger, again designated by 13. By means of the hollow screw 41 enclosing the plunger 13 with play, the connection between the spring plate and the hollow piston 8 is made via the sleeve-shaped part 42 which forms the second component of the spring plate and is not necessarily connected to part 40, again while maintaining the gap a, whereby this Solution offers the advantage of adjustability of this gap.

Die Arbeitsweise der in den Figuren 1 bis 3 dargestellten Pumpedüse ist folgende:The operation of the pump nozzle shown in Figures 1 to 3 is as follows:

In Figur 1 ist angenommen, daß der auf die in der Figur obere Stirnfläche des Hochdruckkolbens 6 arbeitenden Nocken (hier kann auch ein anderes mechanisches oder elektromechanisches Glied vorgesehen sein) sich in seiner Grundkreisphase befindet. Solange das Magnetventil 27 geöffnet ist, wird der Druckraum 7 über die Kanalanordnungen 24 und 29 unter Abfuhr von Gasen und Dämpfen von Kraftstoff durchströmt; die Druckkammer 15 steht mit diesen Kanalanordnungen nicht in Verbindung, wohl aber mit dem zur Düse der Pumpedüse führenden Druckkanal 18. Federteller 10 stützt sich unter der Wirkung der Schließfeder 11 in Richtung nach oben an der Stirnfläche 12 des oberen Gehäuseteils 2 ab, und Hohlkolben 8 ist unter der Wirkung der Druckfeder 14 so weit in Richtung nach oben unter Bildung des Spalts a bewegt, wie dies die durch seine hakenförmigen Fortsätze 22 und den Hinterschnitt 21 gegebene Fangverbindung zuläßt. Elektromagnetventil 27 in der Zufuhrkanalanordnung 24 ist bereits im schließenden Sinne von einem der entsprechenden Brennkraftmaschine zugeordneten Steuergerät angesteuert, so daß durch die Kanalanordnung 24 weder eine Kraftstoffzufuhr noch eine Kraftstoffabfuhr zu bzw. aus dem Druckraum 7 erfolgen kann.In FIG. 1 it is assumed that the cam working on the upper end face of the high-pressure piston 6 in the figure (another mechanical or electromechanical element can also be provided here) is in its base circle phase. As long as the solenoid valve 27 is open, the pressure chamber 7 flows through the channel arrangements 24 and 29 with removal of gases and vapors of fuel; the pressure chamber 15 is not connected to these channel arrangements, but it is connected to the pressure channel 18 leading to the nozzle of the pump nozzle. Spring plate 10 is supported under the action of the closing spring 11 in the upward direction on the end face 12 of the upper housing part 2, and hollow piston 8 is moved under the action of the compression spring 14 as far upwards to form the gap a as the catch connection given by its hook-shaped extensions 22 and the undercut 21 permits. Solenoid valve 27 in the supply channel arrangement 24 is already controlled in the closing sense by a control device assigned to the corresponding internal combustion engine, so that neither a fuel supply nor a fuel discharge to or from the pressure chamber 7 can take place through the channel arrangement 24.

Eine Abwärtsbewegung des Hochdruckkolbens 6 unter der Wirkung des zugeordneten Nockens hat nun zunächst ein Herausdrücken von Gasen und Dämpfen in den Querkanal 28, dann ein Verschließen desselben und schließlich - da das Magnetventil 27 sperrt - einen Druckaufbau im Druckraum 7 zur Folge, der unter Überwindung der Kraft der Feder 14 gemäß Figur 2 zu einer nach unten gerichteten Bewegung des Hohlkolbens 8 bis zur Überwindung des Spalts a führt. Die Einmündungsstelle 18a des Druckkanals 18 ist in Bezug auf die Lage von Querbohrungen in Fortsetzung der Druckkammer 15 so gewählt, daß entsprechend dem Pfeil 29 in Figur 2 während einer relativ kurzen Phase der Auf- und Abwärtsbewegungen des Hohlkolbens 8 der Druckraum 7 zur Kraftstoffbelieferung der Druckkammer 15 mit dieser in Verbindung steht.A downward movement of the high-pressure piston 6 under the action of the assigned cam now has a first pushing out of gases and vapors in the transverse channel 28, then closing the same and finally - since the solenoid valve 27 blocks - a pressure build-up in the pressure chamber 7, which is overcome by overcoming the The force of the spring 14 according to FIG. 2 leads to a downward movement of the hollow piston 8 until the gap a is overcome. The junction 18a of the pressure channel 18 is chosen in relation to the position of transverse bores in a continuation of the pressure chamber 15 such that, according to arrow 29 in FIG. 2, the pressure chamber 7 for supplying fuel to the pressure chamber during a relatively short phase of the upward and downward movements of the hollow piston 8 15 is connected to this.

Die Abwärtsbewegung des Hohlkolbens 8 bis zur Beseitigung des Abstands a, d. h. bis zur gegenseitigen Kontaktierung der einander zugekehrten Stirnflächen von Hohlkolben 8 und Federteller 10, hat eine Verringerung der axialen Erstreckung der Druckkammer 15 und damit eine Erhöhung des Drucks in ihr zur Folge, die sich als Druckerhöhung im Druckkanal 18 und damit in einer Erhöhung der auf die Düsennadel wirkenden Öffnungskraft äußert: Die Düsennadel 11a wird bis zum Abbau dieses Drucks auf einen durch die Auslegung der Schließfeder 11 gegebenen Wert von ihrem Sitz abgehoben, d. h. es kommt zur Voreinspritzung von Kraftstoff in ein Saugrohr oder einen Brennraum der Brennkraftmaschine.The downward movement of the hollow piston 8 until the distance a is eliminated, that is to say until the mutually facing end faces of the hollow piston 8 and the spring plate 10 come into contact with one another, has the result of a reduction in the axial extent of the pressure chamber 15 and thus an increase in the pressure in it, resulting in as an increase in pressure in the pressure channel 18 and thus in an increase of the opening force acting on the nozzle needle: The nozzle needle 11a is lifted from its seat to a value given by the design of the closing spring 11 until this pressure is released, ie fuel is pre-injected into an intake manifold or a combustion chamber of the internal combustion engine.

Wichtig ist für die genaue Einhaltung von Voreinspritzmenge und Voreinspritzzeit die Tatsache, daß das Ende des Voreinspritzvorgangs nicht durch irgendeinen Abströmvorgang zur Druckverringerung, sondern durch Wirksamwerden eines mechanischen Anschlags, gebildet durch die einander zugekehrten Stirnflächen der Teile 8 und 10, definiert ist.It is important for the precise maintenance of the pre-injection quantity and pre-injection time that the end of the pre-injection process is not defined by any outflow process to reduce the pressure, but by the action of a mechanical stop, formed by the facing end faces of parts 8 and 10.

An die beschriebene Beendigung des Voreinspritzvorgangs schließt sich nun eine Einspritzpause an, d. h. eine Phase, während der die Düsennadel auf ihrem Sitz verbleibt. Unter dem Einfluß des Nockens bewegt sich der Hochdruckkolben 6, wie in Figur 2 dargestellt, unter begrenzter Vergrößerung des Drucks im Druckraum 7 infolge axialer Verkleinerung desselben weiter nach unten, wodurch zunächst auch der Hohlkolben 8 zusammen mit dem Federteller 10 in Richtung Düse entgegen der zunehmenden Kraft der Schließfeder 11 verschoben wird. Diese Verschiebung wird aber beendet, sobald die Schulter 30 des Federtellers 10 sich an dem gehäusefesten Gegenanschlag 31 abstützt. Das bedeutet, daß von diesem Zeitpunkt an weitere nach unten gerichtete Bewegungen des Hochdruckkolbens 6 unmittelbar zu einer Verringerung der axialen Abmessung des Druckraums 7 und damit zu einer Erhöhung des Drucks in ihm führen, die, da nunmehr die Einmündungsstelle 18a des Druckkanals 18 in Höhe eines unteren Bereichs des Druckraums 7 liegt, einen entsprechenden Druckaufbau an der Düsennadel zur Folge hat. Sobald dort ein Druckwert erreicht ist, der infolge des jetzt etwas komprimierten Zustands der Schließfeder 11 höher ist als der für die Voreinspritzung erforderliche Druckwert und der zur Überwindung der Kraft der Schließfeder 11 ausreicht, wird die Düsennadel 11a von ihrem Sitz abgehoben, und der Haupteinspritzvorgang beginnt. Dieser wird beendet durch einen gezielten Druckabbau infolge Ansteuerung des Magnetventils 27 im die Kanalanordnung 24 aufsteuernden Sinne. Diese Öffnungsstellung des Magnetventils 27 ist in Figur 2 dargestellt.The described termination of the pre-injection process is now followed by an injection pause, ie a phase during which the nozzle needle remains in its seat. Under the influence of the cam, the high-pressure piston 6, as shown in FIG. 2, moves further downward with a limited increase in the pressure in the pressure chamber 7 due to the axial reduction thereof, as a result of which the hollow piston 8 together with the spring plate 10 in the direction of the nozzle counter to the increasing one Force of the closing spring 11 is shifted. However, this displacement is ended as soon as the shoulder 30 of the spring plate 10 is supported on the counter stop 31 fixed to the housing. This means that from this point in time further downward movements of the high-pressure piston 6 lead directly to a reduction in the axial dimension of the pressure chamber 7 and thus to an increase in the pressure in it, which, since the junction 18a of the pressure channel 18 now amounts to a is lower region of the pressure chamber 7, a corresponding pressure build-up on the nozzle needle results. As soon as a pressure value is reached there which, due to the now somewhat compressed state of the closing spring 11, is higher than the pressure value required for the pre-injection and which is sufficient to overcome the force of the closing spring 11, the nozzle needle 11a is lifted from its seat and the main injection process begins . This is ended by a targeted Pressure reduction as a result of actuation of the solenoid valve 27 in the sense that controls the channel arrangement 24. This open position of the solenoid valve 27 is shown in Figure 2.

Von Vorteil bei der Erfindung ist auch die Tatsache, daß infolge der Druck- bzw. Kraftübersetzung bei der Voreinspritzung (Wahl des Maßes b und der Größe der Fläche 17) die Ausgestaltung des Nockens zum Antrieb des Hochdruckkolbens 6 erleichtert ist. In jedem Falle verbleibt für die Haupteinspritzung der Nockenbereich maximaler Geschwindigkeit, da für die Voreinspritzung nur ein kleiner Druck bzw. eine kleine Druckerhöhung im Druckraum 7 erforderlich ist.Another advantage of the invention is the fact that the configuration of the cam for driving the high-pressure piston 6 is facilitated due to the pressure or force transmission during the pre-injection (choice of dimension b and the size of the surface 17). In any case, the cam area of maximum speed remains for the main injection, since only a small pressure or a small pressure increase in the pressure chamber 7 is required for the pre-injection.

Durch Veränderung der Größe des Spalts a, der axialen Lage des Gegenanschlags 31 und anderer, den Ablauf des Einspritzvorgangs bestimmender Abmessungen, z. B. durch Austausch vorgefertigter Teile, läßt sich leicht eine Anpassung an die Erfordernisse verschiedener Maschinen vornehmen.By changing the size of the gap a, the axial position of the counterstop 31 and other dimensions determining the course of the injection process, for. B. by exchanging prefabricated parts, can be easily adapted to the requirements of different machines.

Nach Beendigung der Haupteinspritzung erfolgt ein weiterer Druckabbau im Druckraum 7, und zwar zunächst durch Druckangleichung über die Kanalanordnung 24 und dann durch erneute Aufwärtsbewegung des Hochdruckkolbens 6, ermöglicht durch die Form des Nockens. Die sich etwas entspannende Schließfeder 11 drückt den Hohlkolben 8 und den Federteller 10 nach oben, bis sich letzterer an die Stirnfläche 12 des Gehäuseteils 2 anlegt; die Feder 14 in der Druckkammer 15 sorgt für die weitere Aufwärtsbewegung des Hohlkolbens 8 unter Bildung des Spalts a, bis die hakenartigen Fortsätze 22 in Verbindung mit dem Hinterschnitt 21 eine weitere Axialbewegung des Hohlkolbens 8 unterbinden: die in Figur 1 dargestellte Ausgangslage der verschiedenen Teile ist wieder erreicht.After the main injection has ended, there is a further reduction in pressure in the pressure chamber 7, first by equalizing the pressure via the channel arrangement 24 and then by renewed upward movement of the high-pressure piston 6, made possible by the shape of the cam. The somewhat relaxing closing spring 11 presses the hollow piston 8 and the spring plate 10 upwards until the latter contacts the end face 12 of the housing part 2; the spring 14 in the pressure chamber 15 ensures the further upward movement of the hollow piston 8, forming the gap a, until the hook-like extensions 22 in conjunction with the undercut 21 prevent further axial movement of the hollow piston 8: the starting position of the various parts shown in FIG. 1 reached again.

Wie auch aus der Beschreibung von Ausführungsbeispielen ersichtlich, bietet die Erfindung nicht nur grundlegende Vorteile hinsichtlich der Arbeitsweise, insbesondere hinsichtlich der genauen Einhaltung von Voreinspritzmenge und -zeit, sondern auch bezüglich der Kühlung und damit der genauen Einhaltung auch für die Einspritzparameter wichtiger Abmessungen (Spaltmaße) sowie hinsichtlich der einfachen Fertigung.As can also be seen from the description of exemplary embodiments, the invention offers not only fundamental advantages with regard to the mode of operation, in particular with regard to the precise ones Adherence to the pre-injection quantity and time, but also with regard to cooling and thus exact compliance with dimensions (gap dimensions) important for the injection parameters as well as with regard to simple production.

Abschließend sei darauf hingewiesen, daß verständlicherweise die erfindungsgemäßen Maßnahmen im Rahmen der Voreinspritzung mit Vorteil auch bei einer normalen Einspritzdüse (ggf. ohne angebautes Elektromagnetventil), die nicht mit einer Pumpe kombiniert ist, Einsatz finden können.In conclusion, it should be pointed out that, understandably, the measures according to the invention in the context of the pre-injection can advantageously also be used with a normal injection nozzle (possibly without an attached electromagnetic valve), which is not combined with a pump.

Claims (12)

  1. Fuel-injection device arranged for the purpose of injecting the pre-injection and main injection quantities of fuel and having a housing (2, 3, 4) in which is received in a longitudinally displaceable manner and in sequence in this direction a high pressure piston (6), a pressure chamber (7) and a hollow piston (8),
    wherein the high pressure piston (6) is subjected at times to an actuating force which acts upon its end face remote from the pressure chamber (7) causing a longitudinal displacement in the direction of the hollow piston (8) which is supported by way of a first spring (14) in the direction of the high pressure piston (6),
    furthermore having a solenoid valve (27) within a duct arrangement between a fuel supply line (23a) to the injection device and the pressure chamber (7) which is controlled in the direction blocking this duct arrangement during injection processes,
    furthermore having a pressure chamber (15) which is formed in the hollow piston (8) and is defined in a longitudinal direction by a pressure surface on the hollow piston (8), wherein the pressure surface is smaller than an end face (17) of the hollow piston (8) adjacent to the pressure chamber (7), so that its volume is compressed in the longitudinal direction against the force of the spring (14) during a first range of longitudinal movements of the hollow piston (8), causing a defined pre-injection quantity of fuel to be supplied by way of a pressure duct (18) which is fixed to the housing, communicates with an injection needle (11a) of the injection device and is flow connected to the pressure chamber (7),
    and having a counterstop (31), which is fixed to the housing, for terminating an injection pausing stroke of the hollow piston (8) which follows on from the pre-injection stroke,
    characterised in that a plunger (13), which is provided on both sides with cylindrical projections (13a, 13b) protrudes into the hollow piston (8) which encompasses the pressure chamber (15), wherein the spring (14) which Is disposed coaxial to the upper projection (13a) is supported at one end on the plunger (13) and at the other end on an inner surface (16) of the hollow piston (8) and wherein the pressure surface is defined by the radius (b) of the pressure chamber (15) and the upper projection (13a), and wherein the spring (14) holds the lower projection (13b) in position with a spring plate (10) which for its part is inserted into the housing (2, 3, 4) by a second spring (11), which is dimensioned greater than the spring (14) and simultaneously forms a closing spring of the injection needle (11a), influenced in the direction of the pressure chamber (7) displaceable in a longitudinal direction, and wherein for the purpose of initiating the pre-injection stroke the spring plate (10) adjacent to a lower end face (12) of a housing part (2) is at a small spaced disposition (a) with respect to the hollow piston (8), which space is overcome for the purpose of injecting the pre-injection quantity by means of the longitudinal movement of the hollow piston (8), Wherein the relative displacement of the plunger (13) in the hollow piston (8) displaces the pre-injection quantity of fuel,
    and wherein in order to terminate the injection pausing stroke a stop formed as a shoulder (30) on the spring plate (10) moves into position against the housing-side counterstop (31).
  2. Injection device according to claim 1, characterised in that the spring plate (10) is capture-connected (21, 22) to the hollow piston (8)* for longitudinal movements in the direction of the high pressure piston (6).
  3. Injection device according to claim 2, characterised in that the hook-shaped extensions (22) on the hollow piston (8) protrude into a hollow cylindrical region (19) of the spring plate (10) provided with undercuts (21 ) and engage behind said undercuts.
  4. Injection device according to claim 3, characterised by radial recesses (23) in the hollow cylindrical region (19) at the level of the undercuts (21).
  5. Injection device according to claim 2, characterised in that the capture-connection comprises a hollow screw (41) which surrounds the plunger (13) in regions and is screwed into an inner thread in the hollow piston (8).
  6. Injection device according to any one of claims to 5, characterised in that the high pressure piston (6), pressure chamber (7) and hollow piston (8) are received by a bore (1) of constant diameter in the housing (2, 3, 4).
  7. Injection device according to claim 6, characterised in that the housing is subdivided into a first housing part (2) which comprises a sealing guide for the hollow piston (8) and a second housing part (3) comprising a rough guide (9) having a greater diameter for the spring plate (10).
  8. Injection device according to any one of claims 1 to 7, characterised by duct arrangements (24, 29) which extend substantially in the longitudinal direction in the wall of the housing (2, 3, 4) for supplying and carrying-off fuel.
  9. Injection device according to claim 8, characterised in that transverse ducts (26, 28) of the duct arrangements (24, 29) for supplying and carrying-off fuel issue simultaneously into a region of the pressure chamber (7) which is adjacent to the hollow piston or adjacent to a high pressure piston when the hollow piston (9) is located in an inoperative position and the pressure chamber (7) is at its maximum longitudinal dimension.
  10. Injection device according to any one of claims to 9, characterised in that a fuel supply line and fuel carrying-off line (23a, 30) are provided leading to or from the injection device at a region of the housing (2, 3, 4) adjacent to the injection nozzle.
  11. Injection device according to any one of claims 1 to 10, characterised by a connection duct arranged in the housing (2, 3, 4) in such a manner that it connects the pressure chamber (7) to the pressure chamber (15) at times for the purpose of supplying fuel after termination of the pre-injection stroke of the hollow piston (8).
  12. Injection device according to claim 11, characterised in that the connection duct Is formed by means of a pressure chamber-side junction site (18a) of the pressure duct (18).
EP94117904A 1993-12-02 1994-11-12 Fuel injection device for pilot and main injection Expired - Lifetime EP0656472B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE4341089 1993-12-02
DE4341089 1993-12-02

Publications (2)

Publication Number Publication Date
EP0656472A1 EP0656472A1 (en) 1995-06-07
EP0656472B1 true EP0656472B1 (en) 1997-04-16

Family

ID=6504011

Family Applications (1)

Application Number Title Priority Date Filing Date
EP94117904A Expired - Lifetime EP0656472B1 (en) 1993-12-02 1994-11-12 Fuel injection device for pilot and main injection

Country Status (3)

Country Link
EP (1) EP0656472B1 (en)
DE (2) DE4405309C1 (en)
ES (1) ES2100615T3 (en)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB9507115D0 (en) * 1995-04-06 1995-05-31 Lucas Ind Plc Fuel pumping apparatus
DE19755591A1 (en) * 1997-12-15 1999-06-17 Volkswagen Ag Fuel injection device for IC engines
US6227175B1 (en) * 1999-12-27 2001-05-08 Detroit Diesel Corporation Fuel injector assembly having a combined initial injection and a peak injection pressure regulator
DE10022421A1 (en) * 2000-05-09 2001-11-15 Bosch Gmbh Robert Pre-injection valve for controlling the fuel flow of a fuel injector

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3334619C2 (en) * 1983-09-24 1995-01-19 Bosch Gmbh Robert Fuel injector
DE3610360A1 (en) * 1986-03-27 1987-10-01 Bosch Gmbh Robert FUEL INJECTION NOZZLE FOR INTERNAL COMBUSTION ENGINES
DE3629754C2 (en) * 1986-09-01 1994-07-14 Bosch Gmbh Robert Device for generating pilot injections in pump nozzles
DE3629751C2 (en) * 1986-09-01 1998-07-02 Bosch Gmbh Robert Pre-injection device for internal combustion engines
DE3731240C2 (en) * 1987-09-17 1995-04-06 Volkswagen Ag Injector

Also Published As

Publication number Publication date
DE4405309C1 (en) 1995-04-20
EP0656472A1 (en) 1995-06-07
DE59402437D1 (en) 1997-05-22
ES2100615T3 (en) 1997-06-16

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