EP0267421B1 - Fuel injection nozzle for internal-combustion engines - Google Patents

Fuel injection nozzle for internal-combustion engines Download PDF

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Publication number
EP0267421B1
EP0267421B1 EP19870114511 EP87114511A EP0267421B1 EP 0267421 B1 EP0267421 B1 EP 0267421B1 EP 19870114511 EP19870114511 EP 19870114511 EP 87114511 A EP87114511 A EP 87114511A EP 0267421 B1 EP0267421 B1 EP 0267421B1
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EP
European Patent Office
Prior art keywords
valve needle
piston
nozzle
stop
valve
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
Application number
EP19870114511
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German (de)
French (fr)
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EP0267421A1 (en
Inventor
Karl Hofmann
Paul Dipl.-Ing. Füssner
Kurt Seifert
Wilhelm Christ
Siegfried Schlaf
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Robert Bosch GmbH
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Robert Bosch GmbH
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Publication of EP0267421A1 publication Critical patent/EP0267421A1/en
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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • 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
    • 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
    • F02M45/00—Fuel-injection apparatus characterised by having a cyclic delivery of specific time/pressure or time/quantity relationship
    • F02M45/02—Fuel-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
    • F02M45/04—Fuel-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
    • F02M45/08—Injectors peculiar thereto
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M2200/00—Details of fuel-injection apparatus, not otherwise provided for
    • F02M2200/50—Arrangements of springs for valves used in fuel injectors or fuel injection pumps
    • F02M2200/505—Adjusting spring tension by sliding spring seats

Definitions

  • a pump piston bush in which a pump piston can be moved back and forth, and a nozzle body, in which a valve seat is formed and a valve needle lifting off inwardly, is displaceably mounted, are adjacent an intermediate washer, an intermediate bush is connected, in which a hollow, displaceable between two stops, a hollow evasive piston and a spring which is surrounded by the latter and on the one hand supporting and on the other acting on the valve needle are arranged in a bore.
  • the intermediate bushing has a fuel inlet channel with a valve seat forming the first stop, with which a valve part on the pressure side of the evasive piston interacts.
  • the second stop is towards the nozzle body on the washer.
  • the closing spring and the evasive piston with its valve part are arranged in a bore of a nozzle holding body designed as a screw part, against which the nozzle body is tensioned with the interposition of an intermediate disk.
  • the valve seat forming the stop and the fuel inlet channel are also formed in the nozzle holder body.
  • a fuel injection nozzle in which in a sleeve-shaped part of a two-part nozzle holder, against the other part of which the nozzle body rests, a spring-loaded adjusting piston is displaceable, which has a valve cone Relief hole controls.
  • an evasive piston In an inner bore of the actuating piston, an evasive piston can also be displaced, which controls a flattening of the increase in the quantity of the injection quantity after the start of injection.
  • GB-A 20 17 210 shows an injection nozzle with a nozzle holding body, in which a sleeve is displaceably mounted in a bore, which is acted upon by a control pressure separate from the injection pressure and which serves to change the stroke of the valve needle.
  • the invention has for its object to provide a fuel injector in which a pre-injection and main injection is controlled with an evasive piston, and in which the arrangement of the evasive piston is designed in a simple manner.
  • This object is achieved according to the invention by the combination of features specified in claim 1.
  • the fuel injection nozzle according to the invention has the advantage that the material for the intermediate bushing which guides the escape piston and forms the valve seat at the entrance to the cylinder chamber of the backup piston can be selected independently of the requirements imposed on the holding body. Furthermore, a normal hardening process is possible for the intermediate bushing, whereas special measures would have to be taken when hardening the holding body in order to keep the threads on the connecting piece for the fuel supply line soft.
  • the intermediate bush is also easier to handle during grinding, lapping and other manufacturing processes than the holding body provided with the threaded connector. A uniform component can be provided for the intermediate bush; the changes in length for different versions are accommodated in the holding body. In the case of scrap or replacement after wear, only the intermediate bush is to be replaced, which is smaller and cheaper than the holding body.
  • FIG. 1 An embodiment of the invention is shown in the drawing and explained in more detail in the following description.
  • the figure shows, on an enlarged scale, a longitudinal section through the combustion chamber-side section of an injection nozzle for a self-igniting internal combustion engine.
  • the injection nozzle has a nozzle body 10 which, together with an intermediate disk 12 and an intermediate bush 14, is clamped against a nozzle holder 18 by a union nut 16.
  • a valve seat is formed which is directed counter to the fuel flow and is arranged upstream of at least one spray orifice and a valve needle 20 which is lifted inward therefrom is slidably mounted.
  • the nozzle holder 18 has a connecting piece, not shown in the drawing, for a fuel feed line, from which a channel 22 leads to a pressure chamber in the nozzle body 10 surrounding the valve needle 20, from which the fuel reaches the valve seat.
  • the valve needle 20 In the area of the pressure chamber, the valve needle 20 has a pressure shoulder on which the fuel acts in the opening direction of the valve needle.
  • the intermediate bush 14 is provided with a blind bore 24 which is open toward the intermediate disc 12 and in which an evasive piston 26 is slidably mounted.
  • This has a blind bore 28 which is open towards the intermediate disk 12 and which receives a closing spring 30 which acts on the valve needle 20 in the closing direction via a pressure piece 32.
  • the closing spring 30 is supported on the bottom of the blind bore 28 and presses the evasive piston 26 with a sealing edge 33 against a valve seat 34 on the intermediate bush 14.
  • the diameter of the sealing edge 33 on the avoiding piston 26 is considerably smaller than its outer diameter.
  • the escape piston 26 is assigned a second stop shoulder fixed to the housing, which is formed by an annular surface 40 on the upper end face of the intermediate disk 12.
  • the length of the escape piston 26 is dimensioned such that it can execute a stroke h K between the valve seat 34 and the annular surface 40.
  • the valve needle 20 is provided with an annular shoulder 42 which, as usual, with the lower end face of the intermediate disk 12, the total stroke h N of the valve needle 20 limited.
  • the blind bore 28 in the evasive piston 26 and the free space 44 in the intermediate disk 12 are connected by a radial groove 46 in the intermediate disk 12 and a channel 48 passing through the intermediate bush 14 and the nozzle holder 18 to a leakage oil connection, not shown, on the nozzle holder 18.
  • the diameter of the sealing edge 33 of the evasive piston 26 is so matched to the size of the pressure shoulder of the valve needle 20 that the increasing fuel pressure at the start of an injection process initially only lifts the valve needle 20 from its seat and shifts it by the pre-injection stroke.
  • the fuel pressure has risen to such an extent that it also lifts the escape piston 26 from the valve seat 34, whereupon the fuel pressure in the fuel chamber 38 abruptly acts on the entire cross-sectional area of the escape piston 26.
  • the evasive piston 26 is thereby displaced by the distance h K , at the end of which it strikes the intermediate disk 12.
  • fuel flows into the fuel chamber 38, as a result of which the pressure rise curve of the fuel suffers a drop.
  • the closing spring 30 is biased more strongly by the displacement of the escape piston 26.
  • the parts can be matched to one another and to the delivery characteristics of the injection pump in such a way that the valve needle 20 is temporarily returned to its valve seat in idle and in the lower part-load range.
  • the fuel pressure continues to rise after the evasive piston 26 strikes the intermediate plate 12 and the fuel chamber 38 is filled, the valve needle 20 possibly from The valve seat is lifted off again and moved in the opening direction until it has covered the total stroke h N.
  • the adjustment can also be such that at higher speeds the pressure rise of the fuel takes place so quickly that the valve needle movement is not reversed at the end of the preliminary stroke, but is only braked temporarily. After the pressure stage, the majority of the fuel is injected. At the end of the injection process, the valve needle 20 and the evasive piston 26 return to the starting position shown.

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

Description

Stand der TechnikState of the art

Bei einer Pumpendüsebaueinheit nach der EP-A 267 177 (nicht vorver­öffentlichtes Dokument) ist zwischen einer Pumpenkolbenbüchse, in der ein Pumpenkolben hin- und herbewegbar ist, und einem Düsenkörper, in dem ein Ventilsitz gebildet und eine nach innen abhebende Ventilnadel verschiebbar gelagert ist, neben einer Zwischenscheibe eine Zwischen­buchse geschaltet, in welcher in einer Bohrung ein zwischen zwei Anschlägen verschiebbarer, hohler Ausweichkolben und eine von diesem umgebenen und einerseits diesen abstützenden und andererseits auf die Ventilnadel einwirkende Schließfeder angeordnet sind. Zur Pumpen­kolbenbuchse hin hat die Zwischenbuchse einen Kraftstoffzulaufkanal mit einem den ersten Anschlag bildenden Ventilsitz, mit dem ein Ventilteil auf der Druckseite des Ausweichkolbens zusammenwirkt. Der zweite Anschlag befindet sich zum Düsenkörper hin an der Zwischen­scheibe. Beim Förderhub des Pumpenkolbens hebt bei Druckanstieg zu­nächst die Ventilnadel entgegen der Schließfederkraft vom Ventilsitz ab, so daß eine Voreinspritzung beginnt. Bei weiterem Druckanstieg hebt auch der Ventilteil des Ausweichkolbens von seinem Sitz ab, wobei ein großes Ausweichvolumen vor der Druckseite des Ausweich­kolbens freigegeben wird, so daß es zu einer schlagartigen Druckent­lastung kommt, infolge der die Ventilnadel wieder auf den Ventilsitz zurückkehrt. Wenn darauf bei weiterer Kraftstofförderung der Aus­weichkolben am zweiten Anschlag zur Anlage kommt, steigt der Druck wieder an, so daß bei Erreichen des Düsenöffnungsdruckes die Haupt­einspritzung erfolgt.In a pump nozzle assembly according to EP-A 267 177 (not a previously published document), a pump piston bush, in which a pump piston can be moved back and forth, and a nozzle body, in which a valve seat is formed and a valve needle lifting off inwardly, is displaceably mounted, are adjacent an intermediate washer, an intermediate bush is connected, in which a hollow, displaceable between two stops, a hollow evasive piston and a spring which is surrounded by the latter and on the one hand supporting and on the other acting on the valve needle are arranged in a bore. Towards the pump piston bushing, the intermediate bushing has a fuel inlet channel with a valve seat forming the first stop, with which a valve part on the pressure side of the evasive piston interacts. The second stop is towards the nozzle body on the washer. During the delivery stroke of the pump piston, when the pressure rises, the valve needle first lifts off the valve seat against the closing spring force, so that a pre-injection begins. If the pressure rises further, the valve part of the evasive piston lifts off its seat, a large evasive volume being released in front of the pressure side of the evasive piston, so that there is an abrupt pressure relief, as a result of which the valve needle returns to the valve seat. If the evasive piston comes to rest on the second stop when the fuel is delivered, the pressure rises again, so that the main injection takes place when the nozzle opening pressure is reached.

Bei einer ähnlich aufgebauten Einspritzdüse nach Figur 2 der oben angeführten EP-A 267 177 sind die Schließfeder und der Ausweichkolben mit seinem Ventilteil in einer Bohrung eines als ein Schraubteil ausgebildeten Düsenhaltekörpers angeordnet, gegen den der Düsenkörper unter Zwischenschaltung einer Zwischenscheibe gespannt ist. Der den Anschlag bildende Ventilsitz und der Kraftstoffzulaufkanal sind eben­falls im Düsenhaltekörper ausgebildet.In a similarly constructed injection nozzle according to FIG. 2 of the above-mentioned EP-A 267 177, the closing spring and the evasive piston with its valve part are arranged in a bore of a nozzle holding body designed as a screw part, against which the nozzle body is tensioned with the interposition of an intermediate disk. The valve seat forming the stop and the fuel inlet channel are also formed in the nozzle holder body.

Aus der DE-A 23 01 628 (Figur 4) ist eine Kraftstoff-Einspritzdüse bekannt, bei der in einem büchsenförmigen Teil eines zweiteiligen Düsenhalters, gegen dessen anderes Teil der Düsenkörper anliegt, ein von einer Feder belasteter Stellkolben verschiebbar, der mit einem Ventilkegel eine Entlastungsbohrung steuert. In einer Innenbohrung des Stellkolbens ist ferner ein Ausweichkolben verschiebbar, der eine Abflachung der Mengenzunahme der Einspritzmenge anschließend an den Einspritzbeginn steuert.From DE-A 23 01 628 (Figure 4) a fuel injection nozzle is known, in which in a sleeve-shaped part of a two-part nozzle holder, against the other part of which the nozzle body rests, a spring-loaded adjusting piston is displaceable, which has a valve cone Relief hole controls. In an inner bore of the actuating piston, an evasive piston can also be displaced, which controls a flattening of the increase in the quantity of the injection quantity after the start of injection.

Außerdem zeigt die GB-A 20 17 210 eine Einspritzdüse mit einem Düsen­haltekörper, in dem in einer Bohrung eine Büchse verschiebbar ge­lagert ist, die von einem vom Einspritzdruck gesonderten Steuerdruck beaufschlagt wird, und die dazu dient, den Hub der Ventilnadel zu verändern.In addition, GB-A 20 17 210 shows an injection nozzle with a nozzle holding body, in which a sleeve is displaceably mounted in a bore, which is acted upon by a control pressure separate from the injection pressure and which serves to change the stroke of the valve needle.

Aufgabe und LösungTask and solution

Der Erfindung liegt die Aufgabe zugrunde, eine Kraftstoff-Einspritz­düse zu schaffen, bei der mit einem Ausweichkolben eine Vor- und Haupteinspritzung gesteuert wird, und bei der die Anordnung des Aus­weichkolbens in einfacher Weise gestaltet ist. Diese Aufgabe wird erfindungsgemäß durch die im Anspruch 1 angegebenen Merkmalskom­bination gelöst.The invention has for its object to provide a fuel injector in which a pre-injection and main injection is controlled with an evasive piston, and in which the arrangement of the evasive piston is designed in a simple manner. This object is achieved according to the invention by the combination of features specified in claim 1.

Vorteile der ErfindungAdvantages of the invention

Die erfindungsgemäße Kraftstoff-Einspritzdüse hat den Vorteil, daß der Werkstoff für die den Ausweichkolben führende und den Ventilsitz am Eingang zur Zylinderkammer des Ausweichkolbens bildende Zwischen­buchse unabhängig von den an den Haltekörper gestellten Anforderungen gewählt werden kann. Ferner ist für die Zwischenbuchse ein normales Härteverfahren möglich, wogegen beim Härten des Haltekörpers beson­dere Maßnahmen getroffen werden müßten, um daff Gewinde am Anschluß­stutzen für die Kraftstoffzuleitung weich zu erhalten. Die Zwischen­buchse ist ferner besser handhabbar beim Schleifen, Läppen und anderen Fertigungsvorgängen als der mit dem Gewindestutzen versehene Haltekörper. Für die Zwischenbuchse kann ein einheitliches Bauteil vorgesehen werden; die Baulängenänderungen für verschiedene Aus­führungen sind im Haltekörper untergebracht. Bei Ausschuß bzw. Ersatz nach Verschleiß ist nur die Zwischenbuchse auszuwechseln, die kleiner und billiger als der Haltekörper ist.The fuel injection nozzle according to the invention has the advantage that the material for the intermediate bushing which guides the escape piston and forms the valve seat at the entrance to the cylinder chamber of the backup piston can be selected independently of the requirements imposed on the holding body. Furthermore, a normal hardening process is possible for the intermediate bushing, whereas special measures would have to be taken when hardening the holding body in order to keep the threads on the connecting piece for the fuel supply line soft. The intermediate bush is also easier to handle during grinding, lapping and other manufacturing processes than the holding body provided with the threaded connector. A uniform component can be provided for the intermediate bush; the changes in length for different versions are accommodated in the holding body. In the case of scrap or replacement after wear, only the intermediate bush is to be replaced, which is smaller and cheaper than the holding body.

Zeichnungdrawing

Ein Ausführungsbeispiel der Erfindung ist in der Zeichnung darge­stellt und in der nachfolgenden Beschreibung näher erläutert. Die Figur zeigt in vergrößertem Maßstab einen Längsschnitt durch den brennraumseitigen Abschnitt einer Einspritzdüse für eine selbst­zündende Brennkraftmaschine.An embodiment of the invention is shown in the drawing and explained in more detail in the following description. The figure shows, on an enlarged scale, a longitudinal section through the combustion chamber-side section of an injection nozzle for a self-igniting internal combustion engine.

Beschreibung des AusführungsbeispielsDescription of the embodiment

Die Einspritzdüse hat einen Düsenkörper 10, der zusammen mit einer Zwischenscheibe 12 und einer Zwischenbuchse 14 durch eine Überwurf­mutter 16 gegen einen Düsenhalter 18 gespannt ist. Im Düsenkörper 10 ist ein der Kraftstoffströmung entgegengerichteter, mindestens einer Spritzöffnung vorgelagerter Ventilsitz gebildet und eine von diesem nach innen abhebende Ventilnadel 20 verschiebbar gelagert. Der Düsenhalter 18 hat einen in der Zeichnung nicht dargestellten Anschlußstutzen für eine Kraftstoff-Zuleitung, von welchem ein Kanal 22 zu einem die Ventilnadel 20 umgebenden Druckraum im Düsenkörper 10 führt, aus welchem der Kraftstoff zum Ventilsitz gelangt. Im Bereich des Druckraums hat die Ventilnadel 20 eine Druckschulter, an welcher der Kraftstoff im Öffnungssinn der Ventilnadel angreift.The injection nozzle has a nozzle body 10 which, together with an intermediate disk 12 and an intermediate bush 14, is clamped against a nozzle holder 18 by a union nut 16. In the nozzle body 10 a valve seat is formed which is directed counter to the fuel flow and is arranged upstream of at least one spray orifice and a valve needle 20 which is lifted inward therefrom is slidably mounted. The nozzle holder 18 has a connecting piece, not shown in the drawing, for a fuel feed line, from which a channel 22 leads to a pressure chamber in the nozzle body 10 surrounding the valve needle 20, from which the fuel reaches the valve seat. In the area of the pressure chamber, the valve needle 20 has a pressure shoulder on which the fuel acts in the opening direction of the valve needle.

Die Zwischenbuchse 14 ist mit einer zur Zwischenscheibe 12 hin offenen Sackbohrung 24 versehen, in der ein Ausweichkolben 26 verschiebbar gelagert ist. Dieser hat eine zur Zwischenscheibe 12 hin offene Sackbohrung 28, die eine Schließfeder 30 aufnimmt, welche über ein Druckstück 32 im Schließsinn auf die Ventilnadel 20 einwirkt. Die Schließfeder 30 stützt sich am Boden der Sackbohrung 28 ab und drückt den Ausweichkolben 26 mit einer Dichtkante 33 gegen einen Ventilsitz 34 an der Zwischenbuchse 14. Dieser umgibt die Einmündung eines vom Kanal 22 abgezweigten Kanals 36 in eine Kraftstoffkammer 38, die in der Zwischenbuchse 14 zwischen dem Ausweichkolben 26 und dem Boden der Sackbohrung 24 gebildet ist. Der Durchmesser der Dichtkante 33 am Ausweichkolben 26 ist wesentlich kleiner als dessen Außendurchmesser.The intermediate bush 14 is provided with a blind bore 24 which is open toward the intermediate disc 12 and in which an evasive piston 26 is slidably mounted. This has a blind bore 28 which is open towards the intermediate disk 12 and which receives a closing spring 30 which acts on the valve needle 20 in the closing direction via a pressure piece 32. The closing spring 30 is supported on the bottom of the blind bore 28 and presses the evasive piston 26 with a sealing edge 33 against a valve seat 34 on the intermediate bush 14. This surrounds the opening of a duct 36 branched off from the duct 22 into a fuel chamber 38 which is in the intermediate bush 14 is formed between the escape piston 26 and the bottom of the blind bore 24. The diameter of the sealing edge 33 on the avoiding piston 26 is considerably smaller than its outer diameter.

Dem Ausweichkolben 26 ist außer dem Ventilsitz 34 eine zweite gehäusefeste Anschlagschulter zugeordnet, die durch eine Ringfläche 40 an der oberen Stirnseite der Zwischenscheibe 12 gebildet ist. Die Länge des Ausweichkolbens 26 ist so bemessen, daß er zwischen Ventilsitz 34 und Ringfläche 40 einen Hub hK ausführen kann. Die Ventilnadel 20 ist mit einer Ringschulter 42 versehen, die wie üblich mit der unteren Stirnfläche der Zwischenscheibe 12 den Gesamthub hN der Ventilnadel 20 begrenzt. Die Sackbohrung 28 im Ausweichkolben 26 und der Freiraum 44 in der Zwischenscheibe 12 sind durch eine Radialnut 46 in der Zwischenscheibe 12 und einen die Zwischenbuchse 14 und den Düsenhalter 18 durchsetzenden Kanal 48 mit einem nicht dargestellten Leckölanschluß am Düsenhalter 18 verbunden.In addition to the valve seat 34, the escape piston 26 is assigned a second stop shoulder fixed to the housing, which is formed by an annular surface 40 on the upper end face of the intermediate disk 12. The length of the escape piston 26 is dimensioned such that it can execute a stroke h K between the valve seat 34 and the annular surface 40. The valve needle 20 is provided with an annular shoulder 42 which, as usual, with the lower end face of the intermediate disk 12, the total stroke h N of the valve needle 20 limited. The blind bore 28 in the evasive piston 26 and the free space 44 in the intermediate disk 12 are connected by a radial groove 46 in the intermediate disk 12 and a channel 48 passing through the intermediate bush 14 and the nozzle holder 18 to a leakage oil connection, not shown, on the nozzle holder 18.

Die beschriebene Einrichtung arbeitet wie folgt:The described device works as follows:

Der Durchmesser der Dichtkante 33 des Ausweichkolbens 26 ist so auf die Größe der Druckschulter der Ventilnadel 20 abgestimmt, daß der bei Beginn eines Einspritzvorganges ansteigende Kraftstoffdruck zunächst nur die Ventilnadel 20 von ihrem Sitz abhebt und um den Voreinspritzhub verschiebt. Am Ende des Voreinspritzhubes ist der Kraftstoffdruck soweit angestiegen, daß er auch den Ausweichkolben 26 vom Ventilsitz 34 abhebt, worauf der Kraftstoffdruck in der Kraftstoffkammer 38 schlagartig die gesamte Querschnittsfläche des Ausweichkolbens 26 beaufschlagt. Der Ausweichkolben 26 wird dadurch um den Weg hK verschoben, an dessen Ende er an der Zwischenscheibe 12 anschlägt. Bei dieser Bewegung strömt Kraftstoff in die Kraftstoffkammer 38 nach, wodurch der Druckanstiegsverlauf des Kraftstoffs einen Einbruch erleidet. Gleichzeitig wird durch die Verschiebung des Ausweichkolbens 26 die Schließfeder 30 stärker vorgespannt.The diameter of the sealing edge 33 of the evasive piston 26 is so matched to the size of the pressure shoulder of the valve needle 20 that the increasing fuel pressure at the start of an injection process initially only lifts the valve needle 20 from its seat and shifts it by the pre-injection stroke. At the end of the pre-injection stroke, the fuel pressure has risen to such an extent that it also lifts the escape piston 26 from the valve seat 34, whereupon the fuel pressure in the fuel chamber 38 abruptly acts on the entire cross-sectional area of the escape piston 26. The evasive piston 26 is thereby displaced by the distance h K , at the end of which it strikes the intermediate disk 12. During this movement, fuel flows into the fuel chamber 38, as a result of which the pressure rise curve of the fuel suffers a drop. At the same time, the closing spring 30 is biased more strongly by the displacement of the escape piston 26.

Die Teile können so aufeinander und auf die Fördercharakteristik der Einspritzpumpe abgestimmt sein, daß im Leerlauf und im unteren Teillastbereich die Ventilnadel 20 vorübergehend auf ihren Ventilsitz zurückgeführt wird. Im Vollast- und oberen Teillast- bzw. Drehzahlbereich steigt der Kraftstoffdruck nach dem Anschlagen des Ausweichkolbens 26 an der Zwischenscheibe 12 und Auffüllen der Kraftstoffkammer 38 weiter an, wobei die Ventilnadel 20 gegebenenfalls vom Ventilsitz wieder abgehoben und in Öffnungsrichtung verschoben wird, bis sie den Gesamthub hN zurückgelegt hat. Die Abstimmung kann auch so sein, daß bei höheren Drehzahlen der Druckanstieg des Kraftstoffs so schnell erfolgt, daß die Ventilnadelbewegung am Ende des Vorhubes nicht umgekehrt, sondern nur vorrübergehend abgebremst wird. Nach der Druckstufe wird die Hauptmenge des Kraftstoffes eingespritzt. Am Ende des Einspritzvorganges kehren die Ventilnadel 20 und der Ausweichkolben 26 in die dargestellte Ausgangslage zurück.The parts can be matched to one another and to the delivery characteristics of the injection pump in such a way that the valve needle 20 is temporarily returned to its valve seat in idle and in the lower part-load range. In the full-load and upper part-load or speed range, the fuel pressure continues to rise after the evasive piston 26 strikes the intermediate plate 12 and the fuel chamber 38 is filled, the valve needle 20 possibly from The valve seat is lifted off again and moved in the opening direction until it has covered the total stroke h N. The adjustment can also be such that at higher speeds the pressure rise of the fuel takes place so quickly that the valve needle movement is not reversed at the end of the preliminary stroke, but is only braked temporarily. After the pressure stage, the majority of the fuel is injected. At the end of the injection process, the valve needle 20 and the evasive piston 26 return to the starting position shown.

Claims (2)

1. Fuel injection nozzle for internal-combustion engines, having a nozzle body (10) in which a valve seat is formed and a valve needle (20) lifting off inwards from the latter is displaceably mounted, furthermore having a nozzle holder (18) and a closing spring (30) which, on the one side, acts on the valve needle and, on the other side, is supported against an escape piston (26) which is mounted so as to be displaceable between two stops (34, 40) fixed in relation to the housing in a cylinder bore (24) arranged coaxially to the closing spring, the first stop (34), which is situated further away from the valve needle, forming a valve seat which cooperates with a valve part (33) of the escape piston (26) and surrounding a fuel inlet passage (36) which opens into a chamber (38) in the cylinder bore, said chamber being limited by the escape piston, and the closing spring being arranged, over at least part of its length, in a central bore (28) of the escape piston and the stop (40) for the escape piston, which stop faces the valve needle and is fixed in relation to the housing, being provided on the nozzle body or on an intermediate washer (12) clamped between the nozzle body and the nozzle holder and limiting the stroke of the valve needle, and having an intermediate bushing (14) which is clamped between the nozzle holder (18) and the part (12) limiting the stroke of the valve needle (20), in which bushing the escape piston (26) is displaceably mounted and on which also the stop (34) for the escape piston (26) is formed, which stop surrounds the fuel inlet passage (36).
2. Fuel injection nozzle according to Claim 1, characterized in that the intermediate bushing (14) is clamped against the nozzle holder (18) by a union nut (16) which surrounds said intermediate bushing and also clamps the nozzle body (10) or the additional washer (12) against the intermediate bushing.
EP19870114511 1986-11-05 1987-10-05 Fuel injection nozzle for internal-combustion engines Expired - Lifetime EP0267421B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3637729 1986-11-05
DE19863637729 DE3637729A1 (en) 1986-11-05 1986-11-05 FUEL INJECTION NOZZLE FOR INTERNAL COMBUSTION ENGINES

Publications (2)

Publication Number Publication Date
EP0267421A1 EP0267421A1 (en) 1988-05-18
EP0267421B1 true EP0267421B1 (en) 1991-02-06

Family

ID=6313248

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19870114511 Expired - Lifetime EP0267421B1 (en) 1986-11-05 1987-10-05 Fuel injection nozzle for internal-combustion engines

Country Status (3)

Country Link
EP (1) EP0267421B1 (en)
JP (1) JPS63117162A (en)
DE (2) DE3637729A1 (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3907569A1 (en) * 1989-03-09 1990-09-13 Bosch Gmbh Robert FUEL INJECTION NOZZLE FOR INTERNAL COMBUSTION ENGINES

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2301628A1 (en) * 1973-01-13 1974-07-18 Bosch Gmbh Robert FUEL INJECTOR
DE2812519C2 (en) * 1978-03-22 1984-05-30 M.A.N. Maschinenfabrik Augsburg-Nürnberg AG, 8500 Nürnberg Fuel injection nozzle with needle lift control for direct injection internal combustion engines
JPS57102527A (en) * 1980-12-15 1982-06-25 Diesel Kiki Co Ltd Fuel injection nozzle unit
EP0267177A1 (en) * 1986-10-30 1988-05-11 VOEST-ALPINE AUTOMOTIVE Gesellschaft m.b.H. Fuel injection nozzle

Also Published As

Publication number Publication date
EP0267421A1 (en) 1988-05-18
JPS63117162A (en) 1988-05-21
DE3637729A1 (en) 1988-05-11
DE3767972D1 (en) 1991-03-14

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