EP0126947B1 - Fuel injection nozzle for internal-combustion engines - Google Patents

Fuel injection nozzle for internal-combustion engines Download PDF

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Publication number
EP0126947B1
EP0126947B1 EP84104321A EP84104321A EP0126947B1 EP 0126947 B1 EP0126947 B1 EP 0126947B1 EP 84104321 A EP84104321 A EP 84104321A EP 84104321 A EP84104321 A EP 84104321A EP 0126947 B1 EP0126947 B1 EP 0126947B1
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EP
European Patent Office
Prior art keywords
cap
shoulder
valve needle
injection nozzle
fuel
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP84104321A
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German (de)
French (fr)
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EP0126947A3 (en
EP0126947A2 (en
Inventor
Dietrich Dipl.-Ing. Trachte
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Robert Bosch GmbH
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Robert Bosch GmbH
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Filing date
Publication date
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Publication of EP0126947A2 publication Critical patent/EP0126947A2/en
Publication of EP0126947A3 publication Critical patent/EP0126947A3/en
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Publication of EP0126947B1 publication Critical patent/EP0126947B1/en
Expired legal-status Critical Current

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M61/00—Fuel-injectors not provided for in groups F02M39/00 - F02M57/00 or F02M67/00
    • F02M61/16—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
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M61/00—Fuel-injectors not provided for in groups F02M39/00 - F02M57/00 or F02M67/00
    • F02M61/04—Fuel-injectors not provided for in groups F02M39/00 - F02M57/00 or F02M67/00 having valves, e.g. having a plurality of valves in series
    • F02M61/08—Fuel-injectors not provided for in groups F02M39/00 - F02M57/00 or F02M67/00 having valves, e.g. having a plurality of valves in series the valves opening in direction of fuel flow

Definitions

  • the invention relates to a fuel injection nozzle according to the preamble of the main claim.
  • Injection nozzles of this type are the subject of EP-A-0 084 662 published on 3.8.1983, which claims the priorities of 26.1.1982 and 29.5.1982 and therefore belongs to the state of the art according to Art. 54 (3) of the EPC.
  • the opening movement of the valve needle after the undamped advance stroke is delayed or damped by the fact that the fuel can only flow throttled into the expanding damping space.
  • the undamped pre-stroke is achieved in that the cap enclosing the damping chamber rests in the closed position of the valve needle on the end face of the piston-like extension of the valve needle and the length of the extension is dimensioned such that the cap is at a distance from the associated one that corresponds to the undamped pre-stroke locking shoulder fixed to the housing is removed.
  • the cap can initially follow the valve needle unhindered until it strikes the locking shoulder.
  • This arrangement is very simple and may also be done without additional parts.
  • the distance of the cap from the locking shoulder fixed to the housing in the closed position of the valve needle is influenced by a large number of dimensional tolerances, so that exact compliance with the setpoint value of the undamped forward stroke requires very high manufacturing accuracy of several parts or additional adjustment measures.
  • the arrangement according to the invention with the characterizing features of the main claim has the advantage that the desired length of the undamped forward stroke can be exactly maintained with simple means that can be attached already when the injection nozzle is being assembled.
  • the actual length of the forward stroke is only determined by the dimensional tolerances between the support shoulders on the spacer body and between the counter shoulder and the front edge shoulder of the cap.
  • the spacer body is designed as a ring with two differently sized diameter sections, at the transition of which the support shoulder assigned to the counter shoulder of the cap is formed.
  • the larger diameter section of the ring can advantageously overlap an edge flange of the cap and be provided with a plurality of edge notches, between which individual support tabs are formed.
  • the cap can be formed without an edge flange or another circumferential shoulder if, according to a further proposal of the invention, the spacer body is a sleeve provided with a bottom, the depth of which is greater than the length of the cap by the undamped advance stroke.
  • FIG. 1 shows an injection nozzle according to the first embodiment in longitudinal section
  • FIG. 2 enlarges several individual parts of FIG. 1
  • FIG. 3 shows the second embodiment in a representation corresponding to FIG. 2.
  • the injection nozzle according to FIG. 1 has a nozzle body 10 which is clamped to a nozzle holder 14 by a union nut 12.
  • a sleeve 16 Arranged between the nozzle body 10 and the nozzle holder 14 is a sleeve 16 which has an inwardly directed collar 18 which divides a chamber 20 from a chamber 22 of larger diameter in the interior of the injection nozzle.
  • a valve seat 24 is formed in the nozzle body 10 and a valve needle 26 is displaceably mounted, the sealing cone 27 of which is pressed against the valve seat 24 by a closing spring 28.
  • the closing spring 28 is supported on the nozzle body 10 and engages via a flange part 30 on a support disk 32, which in turn is supported on a shoulder 34 of the valve needle 26.
  • an inlet bore 36 is formed, which opens into the chamber 20, which is connected to the chamber 22 via an opening 38 surrounded by the collar 18. From this, a bore 40 in the nozzle body 10 leads into an annular space 42 which is formed between the central bore wall of the nozzle body 10 and the circumference of a section 44 of the valve needle 26 with a reduced diameter and extends directly up to the valve seat 24. There is a distance hg between the flange part 30 and the nozzle body 10 in the illustrated closed position, which corresponds to the total stroke of the valve needle 26.
  • the valve needle 26 is displaced outward in the opening direction by the fuel pressure against the closing spring 28 until the flange part 30 strikes the nozzle body 10. When the valve closes, the closing spring 28 returns the valve needle 26 inward to the closed position shown.
  • a piston-shaped extension 46 adjoins the shoulder 34 of the valve needle 26, which extends through the opening 38 and projects into the chamber 20.
  • the diameter of the extension 46 suitably corresponds to the guide diameter of the valve needle 26.
  • a cap 48 is placed on the extension 46, which has a bottom 50, has a jacket part 52 and a flange edge 54 provided with a plurality of radial slots 53 (FIG. 2).
  • a damping chamber 55 is formed in the cap 48 between the end face of the projection 46 and the base 50, which is connected to the flow path of the fuel in a throttled manner via the radial play between the projection 46 and the jacket part 52 of the cap 48.
  • a spacer ring 56 is pushed onto the jacket part 52 and is provided with an annular flange 58, on the outer circumference of which three axially directed support tabs 60 are formed, which extend over the flange edge 54 of the cap 48 and are evenly distributed.
  • a return spring 62 for the cap 48 engages the ring flange 58 and presses the spacer ring 56 with its support tab 60 against the collar 18 of the sleeve 16.
  • the spacer ring 56 has two support shoulders 64 and 66 which are offset from one another in the axial direction, one of which, 64, is formed by the lower side face of the ring flange 58 and the other, 66, by the end faces of the support tab 60 lying in a common plane is.
  • the support shoulder 64 is assigned to a counter shoulder 68 on the cap 48, which is formed by the upper ring surface of the flange edge 54.
  • the lower side surface of the flange rim 54 forms a front edge shoulder 70 which is assigned to the collar 18 serving as a locking shoulder fixed to the housing.
  • the axial distance between the support shoulders 64, 66 corresponds to the sum of the height of the flange edge 54 and the length of an undamped forward stroke h v .
  • the return spring 62 has placed the spacer ring 56 on the collar 18 and, displacing fuel from the damping space 55, has pushed the cap 48 against the collar 18 to such an extent that between the front edge shoulder 70 of the cap 48 and the collar 18 a gap corresponding to the undamped preliminary stroke h v remains. Due to the increasing fuel pressure at the beginning of an injection process, the valve needle 26 together with extension 46 and cap 48 are initially moved together by the forward stroke h v , the volume of the damping space remaining virtually unchanged and the valve needle movement taking place virtually undamped.
  • the cap 48 comes to rest on the collar 18, which prevents the cap 48 from moving further with the valve needle 26.
  • the fuel can reach the opening 38 practically unthrottled between the support tabs 60 and through the slots 53 in the cap 48 and from there to the valve seat 24 as described.
  • the cap 48 is centered on the valve needle 26 and has a sufficiently large radial play with respect to the nozzle holder 14 so that the valve needle 26 can work without jamming.
  • the return spring 62 for the cap 48 extends partially over the cap 48, so that in this embodiment the means for partially damping the opening stroke of the valve needle 26 take up little space in the axial direction of the injection nozzle.
  • a pre-jet can be formed which practically delivers a constant injection quantity from the start of injection. With appropriately hard damping, a pronounced transition from the pre-jet to the main jet can be achieved.
  • the arrangement described can also be used expediently in the case of those injection nozzles in which the damping is canceled again before the valve needle stroke has ended and as a result a main jet which is clearly separated in terms of quantity and intensity from a pilot jet is generated.
  • an undamped forward stroke of the valve needle can expediently be provided to prevent the valve needle from creeping open.
  • the feed is only determined by the assignment of two parts and is also not influenced when the position of the collar 18 changes, which e.g. can result from an incorrect tightening torque of the union nut 12, plastic or elastic deformation of the nozzle holder 14 and the sleeve 16 or through other manufacturing tolerances.
  • a valve needle 26 ' is provided with a piston-like extension 46' which is weakened in diameter and onto which a cap 48 'is attached, which has a smooth-cylindrical jacket part 52'.
  • the spacer body here is a sleeve 56 'which is plugged onto the cap 48', the base 80 of which forms a support shoulder 64 'which cooperates with the base 50' of the cap 48 'which acts as a counter shoulder 68'.
  • the sleeve 56 ' has a flange edge 82, on which the return spring 62' engages and which forms the second support shoulder 66 ', which is assigned to the housing-fixed collar 18'.
  • This is provided with a plurality of local recesses 84 distributed over the circumference, through which the Fuel can reach valve seat 24 without hindrance.
  • the damping space 55' formed between the cap 48 'and the shoulder 46' has its smallest volume and the front edge shoulder 70 'of the cap 48' facing the collar 18 'is removed from the collar 18' by the amount h v .
  • the cap 48' comes into contact with the collar 18 'after the undamped preliminary stroke h v , after which the further opening movement of the valve needle 26' takes place in a damped manner, as in the exemplary embodiment described above.

Description

Stand der TechnikState of the art

Die Erfindung geht aus von einer Kraftstoff-Einspritzdüse nach der Gattung des Hauptanspruchs.The invention relates to a fuel injection nozzle according to the preamble of the main claim.

Einspritzdüsen dieser Gattung sind Gegenstand der am 3.8.1983 veröffentlichten EP-A-0 084 662, welche die Prioritäten vom 26.1.1982 und 29.5.1982 beansprucht und daher gemäss Art. 54(3) des EPÜ zum Stand der Technik zählt.Injection nozzles of this type are the subject of EP-A-0 084 662 published on 3.8.1983, which claims the priorities of 26.1.1982 and 29.5.1982 and therefore belongs to the state of the art according to Art. 54 (3) of the EPC.

Bei diesen Einspritzdüsen wird die Öffnungsbewegung der Ventilnadel nach dem ungedämpften Vorhub dadurch verzögert bzw. gedämpft, dass der Kraftstoff nur gedrosselt in den sich dabei vergrössernden Dämpfungsraum nachströmen kann. Beim Schliesshub der Ventilnadel ist dafür gesorgt, dass die Ventilnadel ohne Behinderung durch die Dämpfungsmittel rasch in ihre Schliessstellung zurückkehren kann. Der ungedämpfte Vorhub wird dadurch erzielt, dass die den Dämpfungsraum umschliessende Kappe in der Schliessstellung der Ventilnadel auf der Stirnseite des kolbenartigen Ansatzes der Ventilnadel aufliegt und die Länge des Ansatzes so bemessen ist, dass die Kappe um eine dem ungedämpften Vorhub entsprechende Distanz von der ihr zugeordneten gehäusefesten Sperrschulter entfernt ist. Beim Öffnungshub der Ventilnadel kann die Kappe der Ventilnadel zunächst ungehindert folgen, bis sie an der Sperrschulter anschlägt. Diese Anordnung ist sehr einfach und kommt gegebenenfalls auch ohne zusätzliche Teile aus. Jedoch wird der Abstand der Kappe von der gehäusefesten Sperrschulter in der Schliesslage der Ventilnadel von einer Vielzahl von Masstoleranzen beeinflusst, so dass eine exakte Einhaltung des Sollwertes des ungedämpften Vorhubs eine sehr hohe Fertigungsgenauigkeit mehrerer Teile oder zusätzliche Einstellmassnahmen bedingt.With these injection nozzles, the opening movement of the valve needle after the undamped advance stroke is delayed or damped by the fact that the fuel can only flow throttled into the expanding damping space. During the closing stroke of the valve needle, it is ensured that the valve needle can quickly return to its closed position without being impeded by the damping means. The undamped pre-stroke is achieved in that the cap enclosing the damping chamber rests in the closed position of the valve needle on the end face of the piston-like extension of the valve needle and the length of the extension is dimensioned such that the cap is at a distance from the associated one that corresponds to the undamped pre-stroke locking shoulder fixed to the housing is removed. During the opening stroke of the valve needle, the cap can initially follow the valve needle unhindered until it strikes the locking shoulder. This arrangement is very simple and may also be done without additional parts. However, the distance of the cap from the locking shoulder fixed to the housing in the closed position of the valve needle is influenced by a large number of dimensional tolerances, so that exact compliance with the setpoint value of the undamped forward stroke requires very high manufacturing accuracy of several parts or additional adjustment measures.

Vorteile der ErfindungAdvantages of the invention

Die erfindungsgemässe Anordnung mit den kennzeichnenden Merkmalen des Hauptanspruchs hat demgegenüber den Vorteil, dass mit einfachen und bereits beim Zusammenbauen der Einspritzdüse anbringbaren Mitteln die gewünschte Länge des ungedämpften Vorhubs genau eingehalten werden kann. Die tatsächliche Länge des Vorhubs wird nur noch durch die Masstoleranzen zwischen den Stützschultern am Distanzkörper und zwischen Gegenschulter und Stirnrandschulter der Kappe bestimmt.The arrangement according to the invention with the characterizing features of the main claim has the advantage that the desired length of the undamped forward stroke can be exactly maintained with simple means that can be attached already when the injection nozzle is being assembled. The actual length of the forward stroke is only determined by the dimensional tolerances between the support shoulders on the spacer body and between the counter shoulder and the front edge shoulder of the cap.

Durch die in den Unteransprüchen aufgeführten Massnahmen sind vorteilhafte Weiterbildungen der im Hauptanspruch angegebenen Anordnung möglich.The measures listed in the subclaims permit advantageous developments of the arrangement specified in the main claim.

Ein einfacher und wenig Material beanspruchender Distanzkörper ergibt sich, wenn der Distanzkörper als Ring mit zwei unterschiedlich grossen Durchmesserabschnitten ausgebildet ist, an deren Übergang die der Gegenschulter der Kappe zugeordnete Stützschulter gebildet ist. Der grössere Durchmesserabschnitt des Ringes kann vorteilhaft einen Randflansch der Kappe übergreifen und mit mehreren Randausklinkungen versehen sein, zwischen denen einzelne Stützlappen gebildet sind.A simple spacer body that requires little material is obtained if the spacer body is designed as a ring with two differently sized diameter sections, at the transition of which the support shoulder assigned to the counter shoulder of the cap is formed. The larger diameter section of the ring can advantageously overlap an edge flange of the cap and be provided with a plurality of edge notches, between which individual support tabs are formed.

Die Kappe kann ohne Randflansch oder eine sonstige Umfangsschulter ausgebildet werden, wenn gemäss einem weiteren Vorschlag der Erfindung der Distanzkörper eine mit einem Boden versehene Hülse ist, deren Tiefe um den ungedämpften Vorhub grösser als die Länge der Kappe ist.The cap can be formed without an edge flange or another circumferential shoulder if, according to a further proposal of the invention, the spacer body is a sleeve provided with a bottom, the depth of which is greater than the length of the cap by the undamped advance stroke.

Zeichnungdrawing

Zwei Ausführungsbeispiele der Erfindung sind in der Zeichnung dargestellt und in der nachfolgenden Beschreibung näher erläutert. Es zeigen Figur 1 eine Einspritzdüse nach dem ersten Ausführungsbeispiel im Längsschnitt, Figur 2 vergrössert mehrere Einzelteile der Figur 1, und Figur 3 das zweite Ausführungsbeispiel in einer der Figur 2 entsprechenden Darstellung.Two embodiments of the invention are shown in the drawing and explained in more detail in the following description. FIG. 1 shows an injection nozzle according to the first embodiment in longitudinal section, FIG. 2 enlarges several individual parts of FIG. 1, and FIG. 3 shows the second embodiment in a representation corresponding to FIG. 2.

Beschreibung der AusführungsbeispieleDescription of the embodiments

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

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

An die Schulter 34 der Ventilnadel 26 schliesst sich ein kolbenförmiger Ansatz 46 an, welcher durch den Durchbruch 38 hindurchtritt und in die Kammer 20 ragt. Der Durchmesser des Ansatzes 46 entspricht zweckmässig dem Führungsdurchmesser der Ventilnadel 26. Auf den Ansatz 46 ist eine Kappe 48 aufgesetzt, welche einen Boden 50, ein Mantelteil 52 und einen mit mehreren radialen Schlitzen 53 (Fig. 2) versehenen Flanschrand 54 hat. Zwischen der Stirnseite des Ansatzes 46 und dem Boden 50 ist in der Kappe 48 ein Dämpfungsraum 55 gebildet, welcher über das Radialspiel zwischen dem Ansatz 46 und dem Mantelteil 52 der Kappe 48 gedrosselt mit dem Strömungsweg des Kraftstoffs verbunden ist.A piston-shaped extension 46 adjoins the shoulder 34 of the valve needle 26, which extends through the opening 38 and projects into the chamber 20. The diameter of the extension 46 suitably corresponds to the guide diameter of the valve needle 26. A cap 48 is placed on the extension 46, which has a bottom 50, has a jacket part 52 and a flange edge 54 provided with a plurality of radial slots 53 (FIG. 2). A damping chamber 55 is formed in the cap 48 between the end face of the projection 46 and the base 50, which is connected to the flow path of the fuel in a throttled manner via the radial play between the projection 46 and the jacket part 52 of the cap 48.

Auf den Mantelteil 52 ist ein Distanzring 56 aufgeschoben, der mit einem Ringflansch 58 versehen ist, an dessen Aussenumfang gleichmässig verteilt drei axial gerichtete, den Flanschrand 54 der Kappe 48 übergreifende Stützlappen 60 angeformt sind. Am Ringflansch 58 greift eine Rückführfeder 62 für die Kappe 48 an, welche den Distanzring 56 mit seinen Stützlappen 60 gegen den Kragen 18 der Hülse 16 drückt.A spacer ring 56 is pushed onto the jacket part 52 and is provided with an annular flange 58, on the outer circumference of which three axially directed support tabs 60 are formed, which extend over the flange edge 54 of the cap 48 and are evenly distributed. A return spring 62 for the cap 48 engages the ring flange 58 and presses the spacer ring 56 with its support tab 60 against the collar 18 of the sleeve 16.

Durch die beschriebene Ausbildung hat der Distanzring 56 zwei in Achsrichtung zueinander versetzte Stützschultern 64 und 66, von denen die eine, 64, durch die untere Seitenfläche des Ringflansches 58 und die andere, 66, durch die in einer gemeinsamen Ebene liegenden Stirnflächen der Stützlappen 60 gebildet ist. Die Stützschulter 64 ist einer Gegenschulter 68 an der Kappe 48 zugeordnet, welche durch die obere Ringfläche des Flanschrandes 54 gebildet ist. Die untere Seitenfläche des Flanschrandes 54 bildet eine Stirnrandschulter 70, welche dem als gehäusefeste Sperrschulter dienenden Kragen 18 zugeordnet ist. Der axiale Abstand der Stützschultern 64, 66 entspricht der Summe aus der Höhe des Flanschrandes 54 und der Länge eines ungedämpften Vorhubs hv.As a result of the design described, the spacer ring 56 has two support shoulders 64 and 66 which are offset from one another in the axial direction, one of which, 64, is formed by the lower side face of the ring flange 58 and the other, 66, by the end faces of the support tab 60 lying in a common plane is. The support shoulder 64 is assigned to a counter shoulder 68 on the cap 48, which is formed by the upper ring surface of the flange edge 54. The lower side surface of the flange rim 54 forms a front edge shoulder 70 which is assigned to the collar 18 serving as a locking shoulder fixed to the housing. The axial distance between the support shoulders 64, 66 corresponds to the sum of the height of the flange edge 54 and the length of an undamped forward stroke h v .

In der dargestellten Schliesslage der Ventilnadel 26 hat die Rückführfeder 62 den Distanzring 56 an den Kragen 18 angelegt und die Kappe 48 unter Verdrängung von Kraftstoff aus dem Dämpfungsraum 55 soweit gegen den Kragen 18 verschoben, dass zwischen der Stirnrandschulter 70 der Kappe 48 und dem Kragen 18 ein dem ungedämpften Vorhub hv entsprechender Spalt verbleibt. Durch den ansteigenden Kraftstoffdruck am Beginn eines Einspritzvorganges werden zunächst die Ventilnadel 26 samt Ansatz 46 und Kappe 48 gemeinsam um den Vorhub hv verschoben, wobei das Volumen des Dämpfungsraumes annähernd unverändert bleibt und die Ventilnadelbewegung praktisch ungedämpft erfolgt.In the illustrated closed position of the valve needle 26, the return spring 62 has placed the spacer ring 56 on the collar 18 and, displacing fuel from the damping space 55, has pushed the cap 48 against the collar 18 to such an extent that between the front edge shoulder 70 of the cap 48 and the collar 18 a gap corresponding to the undamped preliminary stroke h v remains. Due to the increasing fuel pressure at the beginning of an injection process, the valve needle 26 together with extension 46 and cap 48 are initially moved together by the forward stroke h v , the volume of the damping space remaining virtually unchanged and the valve needle movement taking place virtually undamped.

Am Ende des Vorhubes hv kommt die Kappe 48 zur Anlage am Kragen 18, welcher die Kappe 48 an einer Weiterbewegung mit der Ventilnadel 26 hindert. Bei dieser Weiterbewegung fällt entweder der Druck im Dämpfungsraum 55 ab oder der Druckanstieg im Dämpfungsraum 55 erfolgt langsamer als in der Kammer 20, so dass die Bewegung der Ventilnadel 26 verzögert bzw. gedämpft wird, bis das Flanschteil 30 am Düsenkörper 10 anschlägt und den Öffnungshub beendet. Der Kraftstoff kann zwischen den Stützlappen 60 und durch die Schlitze 53 in der Kappe 48 praktisch ungedrosselt in den Durchbruch 38 und von dort wie beschrieben weiter zum Ventilsitz 24 gelangen.At the end of the preliminary stroke h v , the cap 48 comes to rest on the collar 18, which prevents the cap 48 from moving further with the valve needle 26. During this further movement, either the pressure in the damping chamber 55 drops or the pressure rise in the damping chamber 55 takes place more slowly than in the chamber 20, so that the movement of the valve needle 26 is delayed or damped until the flange part 30 strikes the nozzle body 10 and ends the opening stroke . The fuel can reach the opening 38 practically unthrottled between the support tabs 60 and through the slots 53 in the cap 48 and from there to the valve seat 24 as described.

Beim gedämpften bzw. verzögerten Öffnungshub der Ventilnadel 26 wird Kraftstoff durch das Radialspiel zwischen dem Ansatz 46 und dem Mantelteil 52 der Kappe 48 in den Dämpfungsraum 55 eingedrückt. Bei der Schliessbewegung der Ventilnadel 26 wird über das eingeströmte Kraftstoffpolster im Dämpfungsraum 55 die Kappe 48 mit nach oben genommen, wobei die Rückführfeder 62 der wesentlich stärkeren Schliessfeder 28 nur einen verhältnismässig geringen Widerstand entgegensetzt. Die Rückführfeder 62 ist so bemessen, dass die in den Dämpfungsraum 55 eingeströmte Kraftstoffmenge vom Beginn des Schliesshubs der Ventilnadel 26 bis zum Beginn des nächsten Öffnungshubes bis auf ein Restvolumen aus dem Dämpfungsraum 55 herausgedrückt ist und der Distanzring 55 wieder zur Anlage an den Kragen 18 gekommen ist.During the damped or delayed opening stroke of the valve needle 26, fuel is pressed into the damping space 55 by the radial play between the shoulder 46 and the jacket part 52 of the cap 48. During the closing movement of the valve needle 26, the cap 48 is taken upward via the inflated fuel cushion in the damping chamber 55, the return spring 62 only providing a relatively low resistance to the much stronger closing spring 28. The return spring 62 is dimensioned such that the amount of fuel flowing into the damping chamber 55 is pressed out of the damping chamber 55 from the beginning of the closing stroke of the valve needle 26 to the beginning of the next opening stroke, and the spacer ring 55 comes back into contact with the collar 18 is.

Die Kappe 48 zentriert sich auf der Ventilnadel 26 und hat ein ausreichend grosses radiales Spiel gegenüber dem Düsenhalter 14, so dass die Ventilnadel 26 klemmfrei arbeiten kann. Die Rückführfeder 62 für die Kappe 48 erstreckt sich zum Teil über die Kappe 48 hinweg, so dass bei dieser Ausführung die Mittel zum partiellen Dämpfen des Öffnungshubes der Ventilnadel 26 nur wenig Platz in Achsrichtung der Einspritzdüse benötigen.The cap 48 is centered on the valve needle 26 and has a sufficiently large radial play with respect to the nozzle holder 14 so that the valve needle 26 can work without jamming. The return spring 62 for the cap 48 extends partially over the cap 48, so that in this embodiment the means for partially damping the opening stroke of the valve needle 26 take up little space in the axial direction of the injection nozzle.

Mit der beschriebenen Anordnung lässt sich ein Vorstrahl formen, der praktisch vom Spritzbeginn an eine konstante Einspritzmenge liefert. Bei entsprechend hart ausgelegter Dämpfung lässt sich ein ausgeprägter Übergang von Vorstrahl zu Hauptstrahl erzielen. Die beschriebene Anordnung lässt sich auch bei solchen Einspritzdüsen sinnvoll einsetzen, bei denen die Dämpfung noch vor Beendigung des Ventilnadelhubes wieder aufgehoben und dadurch ein nach Menge und Intensität von einem Vorstrahl deutlich abgesetzter Hauptstrahl erzeugt wird. In diesem Fall kann ein ungedämpfter Vorhub der Ventilnadel zweckmässig dafür vorgesehen sein, ein schleichendes Öffnen der Ventilnadel zu vermeiden. Der Vorschub wird nur durch die Zuordnung zweier Teile bestimmt und auch nicht bei geänderter Lage des Kragens 18 beeinflusst, die sich z.B. durch ein falsches Anzugsmoment der Überwurfmutter 12, plastisches oder elastisches Verformen des Düsenhalters 14 und der Hülse 16 oder durch andere Fertigungstoleranzen ergeben können.With the arrangement described, a pre-jet can be formed which practically delivers a constant injection quantity from the start of injection. With appropriately hard damping, a pronounced transition from the pre-jet to the main jet can be achieved. The arrangement described can also be used expediently in the case of those injection nozzles in which the damping is canceled again before the valve needle stroke has ended and as a result a main jet which is clearly separated in terms of quantity and intensity from a pilot jet is generated. In this case, an undamped forward stroke of the valve needle can expediently be provided to prevent the valve needle from creeping open. The feed is only determined by the assignment of two parts and is also not influenced when the position of the collar 18 changes, which e.g. can result from an incorrect tightening torque of the union nut 12, plastic or elastic deformation of the nozzle holder 14 and the sleeve 16 or through other manufacturing tolerances.

Beim Ausführungsbeispiel nach Figur 3 ist eine Ventilnadel 26' mit einem im Durchmesser geschwächten kolbenartigen Ansatz 46' versehen, auf welchen eine Kappe 48' aufgesteckt ist, die ein glattzylindrisches Mantelteil 52' hat. Der Distanzkörper ist hier eine auf die Kappe 48' aufgesteckte Hülse 56', deren Boden 80 die eine Stützschulter 64' bildet, welche mit dem als Gegenschulter 68' wirkenden Boden 50' der Kappe 48' zusammenarbeitet. Die Hülse 56' hat einen Flanschrand 82, an dem die Rückführfeder 62' angreift und der die zweite Stützschulter 66' bildet, welche dem gehäusefesten Kragen 18' zugeordnet ist. Dieser ist mit mehreren über den Umfang verteilten örtlichen Aussparungen 84 versehen, durch die der Kraftstoff ungehindert zum Ventilsitz 24 gelangen kann.In the exemplary embodiment according to FIG. 3, a valve needle 26 'is provided with a piston-like extension 46' which is weakened in diameter and onto which a cap 48 'is attached, which has a smooth-cylindrical jacket part 52'. The spacer body here is a sleeve 56 'which is plugged onto the cap 48', the base 80 of which forms a support shoulder 64 'which cooperates with the base 50' of the cap 48 'which acts as a counter shoulder 68'. The sleeve 56 'has a flange edge 82, on which the return spring 62' engages and which forms the second support shoulder 66 ', which is assigned to the housing-fixed collar 18'. This is provided with a plurality of local recesses 84 distributed over the circumference, through which the Fuel can reach valve seat 24 without hindrance.

In der dargestellten Schliesslage der Ventilnadel 26' hat der zwischen Kappe 48' und Ansatz 46' gebildete Dämpfungsraum 55' sein kleinstes Volumen und die dem Kragen 18' zugekehrte Stirnrandschulter 70' der Kappe 48' ist um das Mass hv vom Kragen 18' entfernt. Bei der Öffnungsbewegung der Ventilnadel 26' kommt die Kappe 48' nach dem ungedämpften Vorhub hv zur Anlage am Kragen 18', wonach die weitere Öffnungsbewegung der Ventilnadel 26' wie beim vorbeschriebenen Ausführungsbeispiel gedämpft erfolgt.In the illustrated closed position of the valve needle 26 ', the damping space 55' formed between the cap 48 'and the shoulder 46' has its smallest volume and the front edge shoulder 70 'of the cap 48' facing the collar 18 'is removed from the collar 18' by the amount h v . During the opening movement of the valve needle 26 ', the cap 48' comes into contact with the collar 18 'after the undamped preliminary stroke h v , after which the further opening movement of the valve needle 26' takes place in a damped manner, as in the exemplary embodiment described above.

Claims (5)

1. Fuel injection nozzle for internal combustion engines, having a valve needle (26), which is loaded via a closing spring (28), opens in flow direction of the fuel and is connected to a piston (48), the upstream face end of which bounds a damping space (55) which is filled with fuel, in the opening stroke of the valve needle (26) is connected to the flow path of the fuel only via a restriction passage and is formed in a cap (48) fitted on the piston (46), which cap is impinged in opening direction of the valve needle (26) by a return spring (62), comes into contact with a blocking shoulder (18) of the casing by a face rim shoulder (70) after an undamped prestroke of the piston (48) and thereafter remains behind with respect to the further-moving piston (46), with enlargement of the damping space (55), characterized in that the return spring (62) acts on a spacer (56) which is fitted on the cap (48), is displaceably guided on the latter and provided with two supporting shoulders (64, 66), which are axially offset with respect to each other and of which one is assigned to a counter shoulder (68) on the cap (48) and the other is assigned to the blocking shoulder (18) of the casing and which have an axial distance with respect to each other which is greater by the length (hv) of the undamped prestroke than the axial distance of the counter shoulder (68) of the cap (48) from its face rim shoulder (70).
2. Injection nozzle according to Claim 1, characterized in that the spacer is a ring (56) having two diameter sections of different sizes, at the transition of which the supporting shoulder (64) assigned to the counter shoulder (68) of the cap (48) is formed.
3. Injection nozzle according to Claim 2, characterized in that the larger diameter section of the ring (56) overlaps a rim flange (54) of the cap (48).
4. Injection nozzle according to Claim 2 or 3, characterized in that the larger diameter section of the ring (56) is provided with rim notches, between which individual supporting lugs (60) are formed.
5. Injection nozzle according to Claim 1, characterized in that the spacer is a sleeve (56'), provided with a base (80), the depth of which sleeve is greater by the amount of the undamped prestroke (hv) than the length of the cap (48').
EP84104321A 1983-05-25 1984-04-17 Fuel injection nozzle for internal-combustion engines Expired EP0126947B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3318887 1983-05-25
DE19833318887 DE3318887A1 (en) 1983-05-25 1983-05-25 FUEL INJECTION NOZZLE FOR INTERNAL COMBUSTION ENGINES

Publications (3)

Publication Number Publication Date
EP0126947A2 EP0126947A2 (en) 1984-12-05
EP0126947A3 EP0126947A3 (en) 1986-01-22
EP0126947B1 true EP0126947B1 (en) 1988-07-13

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP84104321A Expired EP0126947B1 (en) 1983-05-25 1984-04-17 Fuel injection nozzle for internal-combustion engines

Country Status (4)

Country Link
US (1) US4580728A (en)
EP (1) EP0126947B1 (en)
JP (1) JPS59224465A (en)
DE (2) DE3318887A1 (en)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3329380A1 (en) * 1983-08-13 1985-02-28 Robert Bosch Gmbh, 7000 Stuttgart FUEL INJECTION NOZZLE FOR INTERNAL COMBUSTION ENGINES
DE10006111A1 (en) * 2000-02-11 2001-08-30 Bosch Gmbh Robert Fuel injector

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4034917A (en) * 1975-12-22 1977-07-12 Caterpillar Tractor Co. Variable orifice fuel injection nozzle
DE2948907A1 (en) * 1979-12-05 1981-06-11 Robert Bosch Gmbh, 7000 Stuttgart FUEL INJECTION NOZZLE FOR INTERNAL COMBUSTION ENGINES
DE3006390A1 (en) * 1980-02-21 1981-08-27 Robert Bosch Gmbh, 7000 Stuttgart FUEL INJECTION NOZZLE
DE3105686A1 (en) * 1981-02-17 1982-09-02 Robert Bosch Gmbh, 7000 Stuttgart "FUEL INJECTION NOZZLE"
DE3120060A1 (en) * 1981-05-20 1982-12-09 Robert Bosch Gmbh, 7000 Stuttgart FUEL INJECTION NOZZLE FOR INTERNAL COMBUSTION ENGINES
DE3220398A1 (en) * 1982-01-26 1983-07-28 Robert Bosch Gmbh, 7000 Stuttgart FUEL INJECTION NOZZLE FOR INTERNAL COMBUSTION ENGINES

Also Published As

Publication number Publication date
US4580728A (en) 1986-04-08
JPS59224465A (en) 1984-12-17
EP0126947A3 (en) 1986-01-22
DE3472704D1 (en) 1988-08-18
EP0126947A2 (en) 1984-12-05
JPH0437273B2 (en) 1992-06-18
DE3318887A1 (en) 1984-11-29

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