EP1915525B1 - Divided double seat injection valve member - Google Patents

Description

The invention relates to a split injection valve member with double seat for injecting fuel into the combustion chamber of an internal combustion engine according to the preamble of claim 1.

State of the art

DE 31 13 475 A1 refers to a fuel injector. The fuel injector for use on internal combustion engines comprises a valve needle and a valve needle and this and their pressure chamber in an axial bore with a partially dense radial guide receiving hollow needle. The valve needle and the hollow needle are actuated by the supplied fuel, contrary to the flow direction of the fuel, in the opening direction and loaded by at least one closing spring. The pressure chamber of the valve needle is always connected to an arranged between the valve body and hollow needle pressure chamber of the hollow needle. The hollow needle and the valve needle each control an injection point with at least one injection opening each, wherein the injection points can be opened one after the other and depending on the pressure of the supplied fuel. Both needles are loaded by only one closing spring, which acts at least indirectly on the valve needle and this presses on a seat in the hollow needle and thus provides the hollow needle to a seat in the nozzle body. From a first low fuel pressure first lifts the hollow needle to a stop from its seat, the first injection point is turned on. In this case, the internally guided valve needle is taken, which is moved from a second higher fuel pressure alone against the closing spring and thus aufsteuert the second injection point.

US 5,458,292 shows a fuel injector with a multi-part injection valve member. An internal part of the multi-part injection valve member is guided in an outer injection valve member part. A pressure chamber of the outer injection valve member is acted upon by high-pressure fuel. From this pressure chamber of the outer injection valve member part, the fuel flows to a pressure chamber acting on the inner injection valve member. With the injection valve member arranged in the interior are first fuel injection openings, and with the outside oriordneten Injector valve member are first fuel injection ports, and with the outboard oriented injection valve member part external fuel injection ports are aufsteuerbar.

From the US 4,205,790 an injection valve is known which has an inner needle and an outer needle, wherein the inner needle is disposed within the outer needle. Inside the outer needle, an inner valve seat is formed, with which the inner needle for controlling a fuel flow by a formed in the outer needle and arranged downstream of the inner valve seat bore cooperates. The outer needle cooperates with an outer valve seat formed in the injection valve, so that successively open the inner needle and the outer needle and can each release an injection cross-section.

In today used fuel injectors in which the preferably needle-shaped injection valve member directly from the actuator, such. a piezoelectric actuator, is controlled by this actuator to overcome the needle opening force. The needle opening force results from the product of pressure and the area formed by the needle seat. To reduce this force required to open the injection valve member, the seat diameter must be reduced at the same system pressure. The reduction of the seat diameter of today used fuel injectors on the nozzle body is limited from production and functional point of view possible.

Presentation of the invention

The present invention is therefore based on the object to reduce fuel injectors with dirketer needle control, the force required to actuate the injection valve member.

Following the present invention, the opening of a multi-part injection valve member takes place in two steps. The multipart injection valve member preferably comprises an inner part, which is axially guided in an outer part of the multi-part injection valve member. A pressure chamber, which is acted upon by pressurized fuel under system pressure, is always in fluid communication with a further pressure chamber, which is assigned to the inner part of the multi-part injection valve member. The pending in the pressure chamber system pressure thus always acts on the pressure chamber, which is assigned to the inner part of the multi-part injection valve member.

Inner part and outer part of the multipart injection valve member are designed so that the inner part of the multi-part injection valve member at the combustion chamber end has a seat whose seat diameter is smaller than the seat diameter of the seat of the outer part of the multi-part injection valve member at the combustion chamber end.

Due to the selected seat diameter opens when opening the multi-part injection valve member first, the inner part, so that very small injection quantities can be realized in the combustion chamber of the internal combustion engine. In the injection, which takes place by the opening of the inner part of the multipart injection valve member, builds below the seat of the outer part of the multi-part design multi-part injection valve member and causes its movement in the opening direction until the inner part of the multi-part injection valve member has undergone a stroke. After passage of the stroke is opened by, for example, a mechanical driver, the outer part of the multi-part injection valve member. To open the outer part of a reduced power requirement is necessary, which must be applied by the actuator of the fuel injector, wherein the reduced power requirement from the differential pressure between the pressure p _D in the nozzle body and the pressure below the injection holes p _s and the remaining surface of the seat diameter of the outer part d ₂ minus the bore diameter for the seat d _{1 of} the inner part of the multi-part injection valve member results.

The pressure building up after opening the inner part of the multipart injection valve member below the injection opening pressure is thus used to open the outer part of the multi-part injection valve member and allows the reduction of the opening force, which is applied by the actuator of the fuel injector. It is possible to couple the inner part and the outer part of the multi-part injection valve member by means of a mechanical driver, or to bring about the coupling between the inner part and outer part of the multi-part injection valve member by hydraulic means.

drawing

With reference to the drawing, the invention will be described below in more detail.

Figur 1

eine erste Ausführungsvariante des erfindungsgemäß vorgeschlagenen Kraftstoffinjektors,

Figur 2

einen Querschnitt durch den Düsenkörper mit Innenteil und Außenteil des mehrteilig ausgebildeten Einspritzventilgliedes, die über einen mechanischen Mitnehmer miteinander gekoppelt sind,

Figur 3

eine vergrößerte Darstellung des brennraumseitigen Endes des Kraftstoffinjektors gemäß der Darstellung in Figur 1,

Figur 4

eine weitere Ausführungsvariante des erfindungsgemäß vorgeschlagenen Kraftstoffinjektors,

Figur 5

einen Querschnitt durch den Kraftstoffinjektor gemäß Figur 4 mit Darstellung des Düsenkörpers, des Innenteiles und des Außenteiles eines mehrteiligen Einspritzventilgliedes, die hydraulisch miteinander gekoppelt sind,

Figur 6

eine vergrößerte Darstellung des brennraumseitigen Endes des Kraftstoffinjektors gemäß der Darstellung in Figur 4,

Figuren 6.1, 6.2 und 6.3

Ausführungsvarianten von nadelförmig ausgeführten Einspritzventilgliedern,

Figur 7

eine Sitzgeometrie mit durchgehendem spitzem Kegel,

Figur 8

einen gestuft ausgeführten spitzen Kegel eines Innenteils eines Einspritzventilgliedes und

Figur 9

einen spitzen Kegel am Innenteil mit ebenfalls durchgehendem Kegelwinkel.

It shows:

FIG. 1

A first embodiment variant of the fuel injector proposed according to the invention,

FIG. 2

a cross section through the nozzle body with inner part and outer part of the multi-part injection valve member, which are coupled together via a mechanical driver,

FIG. 3

an enlarged view of the combustion chamber side end of the fuel injector as shown in FIG FIG. 1 .

FIG. 4

a further embodiment variant of the fuel injector proposed according to the invention,

FIG. 5

a cross section through the fuel injector according to FIG. 4 showing the nozzle body, the inner part and the outer part of a multipart injection valve member, which are hydraulically coupled together,

FIG. 6

an enlarged view of the combustion chamber side end of the fuel injector as shown in FIG FIG. 4 .

Figures 6.1, 6.2 and 6.3

Embodiments of needle-shaped injection valve members,

FIG. 7

a seat geometry with a continuous pointed cone,

FIG. 8

a stepped executed pointed cone of an inner part of an injection valve member and

FIG. 9

a pointed cone on the inner part with also continuous cone angle.

embodiments

The representation according to FIG. 1 , A first embodiment of the present invention proposed fuel injector can be seen.

A fuel injector 10, which has an in FIG. 1 In the nozzle body 12, a multipart injection valve member 14 is formed, which includes an inner part 16 and an outer part 18. According to this embodiment, the outer part 18 of the multipart injection valve member 14 is guided on the inner part 16. In the nozzle body, a first pressure chamber 20 is formed, in which system pressure p _D prevails. At the inner part 16 of the multipart injection valve member 14 is a spring element 22. At the periphery of the inner part 16 of the multi-part injection valve member 14 is at least one longitudinal groove 24; the axis of symmetry of the multipart injection valve member 14 is indicated by reference numeral 26.

In the embodiment according to FIG. 1 the inner part 16 and the outer part 18 of the multi-part injection valve 14 are mechanically coupled by means of a driver 28. The driver 28 is attached to an inner peripheral surface of the outer part 18 and surrounds a pin 44 of the inner part 16 of the multi-part injection valve member 14th

At the combustion chamber end of the nozzle body 12 of the fuel injector 10 according to the embodiment in FIG. 1 , There are a number of injection ports 46, through which the fuel under system pressure in an in FIG. 1 not shown combustion chamber of an internal combustion engine can be injected.

The representation according to FIG. 2 is a cross section through the combustion chamber side region of the fuel injector according to the embodiment in FIG. 1 to see section II - II.

Within the nozzle body 12 is in FIG. 2 the first pressure chamber 20 shown in a circle. The pin 44 is enclosed by the driver 28, which is fixedly connected to the inner peripheral surface of the outer part 18 of the multi-part injection valve member, for example, is joined cohesively. In the illustration according to FIG. 2 the driver 28 is sickle-shaped. Instead of in FIG. 2 illustrated geometry of the driver 28, this could also have a semi-circular or other familiar to the expert contour, for example, the driver 28 may be made of two half-shells. To ensure the mechanical coupling via the driver 28, this is firmly connected to the outer part 18 of the multipart injection valve member 14.

FIG. 3 FIG. 10 is an enlarged view of the combustion chamber side end of the fuel injector as shown in FIG FIG. 1 refer to.

As FIG. 3 can be removed, the multi-part injection valve member 14, which is surrounded by the first pressure chamber 20, the inner part 16 with the pin 44, on which in a guide portion 48, the outer part 18 is guided. The stroke, which must be covered by the inner part 16 of the multi-part injection valve member 14 in the opening direction to open the outer part 18 is indicated by reference numeral 30. The as shown in FIG. 2 In a crescent-shaped cross-section formable mechanical driver 28, for example, is materially connected to the peripheral surface of the outer part 18.

• Vom ersten Druckraum 20 im Düsenkörper 12 strömt über mindestens eine Zulaufbohrung 32 unter Systemdruck stehender Kraftstoff einem zweiten Druckraum 34 zu. Der zweite Druckraum 34 ist durch die Außenkontur des Innenteiles 16 und die Innenkontur des Außenteiles 18 definiert. In der Darstellung gemäß Figur 3 sind z.B. zwei Zulaufbohrungen 32 sowie deren Symmetrieachse 50 eingezeichnet. Die Anzahl der Zulaufbohrungen 32 im Außenteil 18 kann unter Berücksichtigung von Festigkeitsgründen beliebig gewählt werden.

The mode of operation of the fuel injector proposed according to the invention is as follows:

• From the first pressure chamber 20 in the nozzle body 12 flows through at least one inlet bore 32 under system pressure fuel to a second pressure chamber 34. The second pressure chamber 34 is defined by the outer contour of the inner part 16 and the inner contour of the outer part 18 defined. In the illustration according to FIG. 3 For example, two inlet bores 32 and their symmetry axis 50 are shown. The number of inlet bores 32 in the outer part 18 can be chosen arbitrarily, taking into account strength reasons.

The inner part 16 includes a first pressure stage 36 and a second pressure stage 38. At the combustion chamber end of the inner part 16 is a seat 40 of the inner part 16 in the outer part 18 of the multipart injection valve member 14. The seat diameter of the seat 40 of the inner part 16 is denoted by d ₁ , The seat 40 of the inner part 16 is located on a bore 52 which is formed at the combustion chamber end of the outer part 18. The bore diameter of the bore 52 is designated by d _B. The outer part 18 has a seat 42 whose diameter is denoted by d ₂ . In the illustration according to FIG. 3 the inner part 16 is placed in its seat 40 in the outer part 18 and the outer part 18 of the multi-part injection valve member 14 in its seat 42 in the nozzle body 12. The opening into the combustion chamber 54 of the internal combustion engine injection openings 46 are therefore closed.

• Zuerst öffnet der Innenteil 16, durch eine Druckabsenkung in einem Steuerraum 13 des Kraftstoffinjektors 10. Die auf das Innenteil 16 wirkende Öffnungskraft wird durch die am Innenteil 16 ausgebildete erste Druckstufe 36 und die am Innenteil 16 ausgebildete zweite Druckstufe 38 erzeugt. Über den nach dem Öffnen des Innenteiles 16 freigegebenen Sitz 40 wird über die Einspritzbohrungen 46 sehr kleine Einspritzmengen in den Brennraum 54 eingespritzt. Vor den Einspritzöffnungen 46 unterhalb des Sitzes 42 des Außenteiles 18 baut sich der Druck p_S auf. Bei weiterem Öffnen des Innenteiles 16 durchläuft dieses den Hubweg 30 und zieht das äußere Nadelteil 18 bei Anschlag am Mitnehmer 28 auf Damit ist zum Öffnen des Außenteiles 18 ein reduzierter Kraftbedarf nötig, der durch den Aktor aufzubringen ist. Der reduzierte Kraftbedarf ergibt sich aus dem Differenzdruck zwischen dem Druck im Düsenkörper p_D und dem Druck vor den Einspritzöffnungen 46 p_s multipliziert mit der Restfläche des Durchmessers d₂ des Sitzes 42 des Außenteiles 18 abzüglich des Durchmessers der Bohrung 52 für den Sitz 40 des Innenteiles 16. Demzufolge wird der nach Öffnen des Innenteiles 16 sich im brennraumseitigen Ende des Düsenkörpers 12 unterhalb des Außenteiles 18 aufbauende Druck zum Öffnen des Außenteiles 18 des mehrteiligen Einspritzventilgliedes 14 genutzt. Dies gestattet eine kleinere Dimmensionierung des Aktors, da die zur Öffnung des mehrteiligen Einspritzventilgliedes 14 erforderliche Öffnungskraft durch die erfindungsgemäß vorgeschlagene Lösung erheblich herabgesetzt ist. Der Differenzdruck Δp ist abhängig von der Restfläche, die sich gemäß der nachfolgenden Beziehung errechnet: $\frac{\mathrm{\pi }}{\mathrm{4}}\left({{\mathrm{d}}_{\mathrm{2}}}^{\mathrm{2}}\mathrm{-}{{\mathrm{<figure-callout\; id="1"\; label="d"\; filenames="imgf0004.png"\; state="\{\{state\}\}">d</figure-callout>}}_{\mathrm{1}}}^{\mathrm{2}}\right)$
  
  mit Δp = p_d - p_s mit p_d Düsendruck und p_s Systemdruck.

The opening of the multi-part injection valve member 14 with the inner part 16 and the outer part 18 proceeds as follows:

• First opens the inner part 16, by a pressure reduction in a control chamber 13 of the fuel injector 10. The force acting on the inner part 16 opening force is generated by the formed on the inner part 16 first pressure stage 36 and formed on the inner part 16 second pressure stage 38. About the released after the opening of the inner part 16 seat 40 46 very small injection quantities is injected into the combustion chamber 54 via the injection holes 46. Before the injection openings 46 below the seat 42 of the outer part 18, the pressure p _S builds up. Upon further opening of the inner part 16, this passes through the stroke 30 and pulls the outer needle member 18 at stop on the driver 28. Thus, to open the outer part 18, a reduced power requirement is necessary, which is applied by the actuator. The reduced power requirement results from the differential pressure between the pressure in the nozzle body p _D and the pressure in front of the injection openings 46 p _s multiplied by the residual area of the diameter d _{2 of} the seat 42 of the outer part 18 minus the diameter of the bore 52 for the seat 40 of the inner part 16. Accordingly, after opening the inner part 16 in the combustion chamber end of the nozzle body 12 below the outer part 18 building pressure for opening the outer part 18 of the multi-part injection valve member 14 is used. This allows a smaller Dimmensionierung of the actuator, since the opening force required for the opening of the multi-part injection valve member 14 is significantly reduced by the proposed solution according to the invention. Of the Differential pressure Δp is dependent on the residual area, which is calculated according to the following relationship: $\frac{\mathrm{\pi }}{\mathrm{4}}\left({{\mathrm{d}}_{\mathrm{2}}}^{\mathrm{2}}\mathrm{-}{{\mathrm{<figure-callout\; id="1"\; label="d"\; filenames="imgf0004.png"\; state="\{\{state\}\}">d</figure-callout>}}_{\mathrm{1}}}^{\mathrm{2}}\right)$
  
  with Δp = p _d - p _s with p _d nozzle pressure and p _s system pressure.

The representation according to FIG. 4 is a further embodiment of the present invention proposed fuel injector with a multi-part injection valve member refer.

The multipart injection valve member 14 according to FIG. 4 , Also includes an inner part 16 and an outer part 18, but in contrast to the embodiment according to FIG FIG. 1 not mechanically but hydraulically coupled with each other. According to the in FIG. 4 illustrated embodiment, the inner part is formed divided and comprises a first part 16.1 and a second part 16.2. The first part 16.1 is traversed by a connecting channel 70, which above an end face 72 (FIG. FIG. 6 ) of the second part 16.2 of the inner part opens.

In the nozzle body 12 of the fuel injector 10 according to FIG. 4 , The first pressure chamber 20 is executed, with reference numeral 46, the injection openings formed at the combustion chamber end of the nozzle body 12 are designated.

FIG. 5 shows a cross section according to the in FIG. 4 Plotted section V - V.

From the illustration according to FIG. 5 shows that the first part 16.1 is completely enclosed by the outer part 18 of the multi-part injection valve member. Reference numeral 70 designates the connecting channel passing through the first part 16.1. The outer part 18 of the multipart injection valve member is enclosed by the first pressure chamber 20 which is bounded by the nozzle body 12.

FIG. 6 shows the combustion chamber end of the embodiment according to FIG. 4 in an enlarged view.

According to this embodiment, the inner part 16 of the multi-part injection valve member 14 comprises a first part 16.1 with a connecting bore 70 and a separate second part 16.2 thereof. Both the first part 16.1 and the second part 16.2 of the split-shaped inner part 16 are enclosed by the outer part 18. The connecting channel 70 of the first part 16.1. opens above an end face 72 of the second part 16.2.

The prevailing in the first pressure chamber 20 system pressure p _D acts via inlet openings 32 in a second pressure chamber 34. The second pressure chamber 34 is defined by the contour of the second part 16.2 and the inner contour of the outer part 18. The first pressure chamber 20 and the second pressure chamber 34 are always in fluid communication with each other, so that in both pressure chambers 20, 34 system pressure p _D is always present. Analogous to the embodiment according to FIG. 1 is the seat 40 of the second part 16.2 of the inner part 16 in the outer part 18 is formed. The seat of the second part 16.2 in the outer part 18 has the diameter d ₁ . The bore 52, on which the seat 40 of the second part 16.2 of the inner part 16 is formed, is embodied in a diameter d _B. Below the end of the outer part 18, a plurality of injection openings 46 are shown, which are distributed approximately in a star shape and allow a uniform injection of fuel into the combustion chamber 54 of the internal combustion engine. The seat 42 of the outer part 18 in the nozzle body 12 has a diameter d ₂ .

In the illustration according to FIG. 6 Both the seat 40 of the second part 16.2 of the inner part 16 and the seat 42 of the outer part 18 of the multi-part injection valve member 14 are closed.

The applied pressure P in the second pressure chamber 34 _D acts on the first pressure stage 36 and the second pressure stage 38 of the second part 16.2 of the inner part 16. The end face 72 of the second part 16.2 of the inner part 16 is prevailing in the control chamber 16 of the fuel injector 10 pressure P _Control applied. If the second part 16.2 of the inner part 16 opens in the opening direction, the seat 40 of the second part 16.2 is opened, so that a small injection quantity can be injected into the combustion chamber 54 via the injection openings 46. Before the injection openings 46, a pressure p _s builds up below the still closed seat 42 of the outer part 18 of the multipart injection valve member. The second part 16.2 continues to open until its end face 72 has passed through the stroke 30. In the connecting channel 70 of each applied pressure p in the control chamber 13 _control rules.

Je nach Auslegung kann d₁ auch gleich d_B sein.After opening the second part 16.2 of the inner part 16 and below the still closed seat 72 of the outer part 18 is under the seat 42 of the outer part 18 of the pressure p _{s in} front of the injection openings 46 at. To open the outer part 18 from the seat 42 a reduced power requirement is necessary, resulting from the pressure difference Δp = p _D - p _s and the remaining surface of the seat diameter d _{2 of} the outer part 18 minus the bore diameter d _{B of} the bore 52 for the seat 40 of second part 16.2 of the inner part 16 of the multi-part injection valve member results. The residual surface of the seat diameter d _{2 of} the outer part minus the bore diameter d _b for the inner part is obtained according to the relationship $\frac{\mathrm{\pi }}{\mathrm{4}}-\left({{\mathrm{d}}_{\mathrm{2}}}^{\mathrm{2}}\mathrm{-}{{\mathrm{<figure-callout\; id="1"\; label="d"\; filenames="imgf0004.png"\; state="\{\{state\}\}">d</figure-callout>}}_{\mathrm{1}}}^{\mathrm{2}}\right)\mathrm{,}$

Depending on the design, d _{1 can} also be d _B.

Both embodiments according to FIG. 1 and FIG. 4 is common that for actuation of the outer part 18 of the multi-part injection valve member 14, a reduced power requirement is required, which must be applied by an actuator, such as a piezoelectric actuator. The smaller this opening force, the smaller the actuator can be designed. It is irrelevant whether the inner part 16 - whether it is integrally formed, it is in two parts, the first part 16.1 and the second part 16.2 comprising - and the outer part 18 hydraulically, according to FIG. 4 coupled to each other, or by means of a mechanically acting driver 28, as in the embodiment according to FIG. 1 shown.

Figure 6.1 shows a multi-part injection valve member 14, whose inner part 16 is formed in several parts and the first part 16.1 and the second part 16.2 includes. According to this embodiment, between the first part 16.1 and the outer part 18 of the multi-part injection valve member 14, a press fit is performed, so that only the second part 16.2 of the inner part 16 is movable relative to the outer part 18 of the multi-part injection valve member 14. Analogous to in FIG. 6 illustrated embodiment, the first pressure chamber 20 and the second pressure chamber 34 via the at least two inlet bores 32 in connection, which are mounted on an axis of symmetry 50 on the outer part 18. On the second part 16.2 of the inner part 16, a first pressure stage 36 and a second pressure stage 38 are executed.

In the lower region of the multipart injection valve member 14, the seat 40 for the second part 16.2 of the inner part 16 is shown in the closed position; the seat 42 of the outer member 18 in the nozzle body 12 of the fuel injector 10 is also closed. In the seat 42 of the outer part 18, the seat 42 on the seat diameter d ₂ ; the seat diameter of the seat 40 of the inner part 16 and of the second part 16.2 of the inner part has a diameter d ₁ . On the outer part 18 of the multipart injection valve member 14 is a bore 52 which is formed in the bore diameter d _B. Below the seat 42 of the outer part 18 are formed in the nozzle body 12 injection openings 46 which may be arranged in a star shape with respect to the axis of symmetry 26 and via which the fuel is injected into the combustion chamber 54 of the internal combustion engine.

The representation according to Figure 6.2 is a further embodiment of an injection valve member refer. According to this embodiment, the inner part 16 of the multi-part injection valve member 14 is integrally formed. In the embodiment according to FIG. 6 illustrated passageway 70 and an end face which can be pressurized by the control chamber, are omitted.

Analogous to the previously described embodiment as shown in FIG Figure 6.1 the one-piece injection valve member 14 an inner part 16 - but executed in one piece - on and an outer part 18. A second pressure chamber 34 within the outer part 18 of the multi-part injection valve member 14 is connected via the inlet bores 32 with the first pressure chamber 20 in connection. The inlet bores 32 are located on the axis of symmetry 50 with respect to the outer part 18. In the first pressure chamber 20, the pressure level b _d prevails while the pressure in front of the injection openings is indicated by p _s . The bore 52 at the combustion chamber end of the outer part 18 is executed in diameter d _B and in the illustration according to Figure 6.2 closed by the seat 40 of the inner part 16 at the diameter d1. Similarly, the seat 42 of the outer part 18 in the nozzle body 12 (see diameter d ₂ ) is also closed. The seat 42 separates the area in the nozzle pressure, p _D from the area in which the pressure level p _s prevails. Analogous to the representation according to Figure 6.1 the injection openings 46 extend as fine channels at the combustion chamber end of the nozzle body 12 and are arranged, for example, star-shaped with respect to the axis of symmetry 26 in the nozzle body 12.

The representation according to Figure 6.3 shows a further embodiment of a multi-part injection valve member, the inner part is formed in several parts and has a first part 16.1 and a second part 16.2. The end face 72 of the second part 16.2 of the multi-part inner part 16 is acted upon via the connecting channel 70 with the pressure prevailing in the control chamber 13. The inner part 16.2 is movably arranged with respect to the outer part 18 of the multi-part injection valve member 14. Via a hydraulic coupling according to this embodiment is given by the connecting channel 70, with which the pressure prevailing in the control chamber 13 pressure level is transmitted to the end face 72 of the second part 16.2 of the multi-part inner part 16.

In the illustration according to Figure 6.3 Both the seat 40 (see seat diameter d ₁ ) and the seat 42 of the outer part 18 (see seat diameter d ₂ ) are closed. Unlike the in Figure 6.1 and 6.2 shown holes 52 at the combustion chamber end of the outer part 18 of the multi-part injection valve member 14 extends the bore 52 at the combustion chamber end of the outer part 18 in the embodiment according to Figure 6.3 funnel-shaped and has a continuously - with respect to the combustion chamber end of the outer part 18 - narrowing diameter.

The representations according to the FIGS. 7 . 8th and 9 different seating geometries of a multipart injection valve member 14 can be seen. For example, the in FIG. 7 illustrated inner part 16 of a multi-part injection valve member 14, be it a one-piece inner part 16, be it a second part 16.2 of a multi-part inner part, a pointed cone on the seat diameter d ₁ at its seat 40 on the inside of the outer part 18th is applied. The seat 42 of the outer part 18 in turn has the seat diameter d ₂ and is in the illustration according to FIG. 7 closed, so that the injection openings extending at the combustion chamber end of the nozzle body 12 are all separated from the area in which nozzle pressure p _D prevails.

Compared to in FIG. 7 illustrated inner part of the multipart injection valve member is formed at the combustion chamber end of the inner part 16 and a second part 16.2 of a split inner part 16, a stepped conical area, at which at the separation of the conical areas of the seat diameter d ₁ prevails, which the seat 40 of the inner part 16 and of the second part 16.2 of the inner part in the outer part 18. The bore 52 at the combustion chamber end of the outer part 18 of the multi-part injection valve member 14 extends in a constant diameter d _B ; the seat diameter of the seat 40 is marked d ₁ , the seat diameter of the seat 42 of the outer part 18 in the nozzle body 12 is designated by the diameter d ₂ . The seat 42, which is in the closed state, separates the area in which the nozzle pressure p _D prevails from the area in which the system pressure p _s prevails. With respect to the axis of symmetry 26 of the nozzle body 12, the injection openings 26 may extend approximately star-shaped at the combustion chamber end of the nozzle body 12.

FIG. 9 Finally, a further embodiment of a nozzle seat geometry can be seen, in which a one-piece formed inner part 16 or the second part 16.2 of a multi-part constructed inner part 16 are placed in the seat 40 of the outer part 18 of the multi-part injection valve member 14. In the outer part 18 of the multi-part injection valve member 14 is the bore 52 which in the in FIG. 9 illustrated embodiment in constant diameter d _{B is} formed. Below the closed seat 42 of the outer part 18 in the nozzle body 12, system pressure p _s prevails, which is separated by the closed seat 42 from the region in which the nozzle pressure p _D prevails.

Compared to the in FIG. 8 shown inner part 16 and the second part 16.2 of a multi-part constructed inner part 16 has the seat geometry according to FIG. 9 a uniform course at the top of the one-piece inner part 16 and the second part 16.2 of the multi-part inner part 16. The tip cone is placed in its seat 40, which adjusts itself at the inlet into the bore 52 in the outer part 18 of the multipart injection valve member 14. Due to the closed seat 42 of the outer part 18, the region in which the nozzle pressure p _D prevails and the region in the system pressure p _s prevails are separated from each other, so that no fuel runs over the star shape in the nozzle body with respect to the axis of symmetry 26 of the fuel injector Injection openings 46 is injected into the combustion chamber 54.

LIST OF REFERENCE NUMBERS

10

fuel injector

12

nozzle body

13

control room

14

multi-part injection valve member

16

Inner part (one-piece, multi-part)

16.1

first part

16.2

second part

18

outer part

20

first pressure chamber

22

spring element

24

longitudinal groove

26

axis of symmetry

28

takeaway

30

stroke

32

inlet bore

34

second pressure chamber

36

first pressure level

38

second pressure level

40

Seat inner part 16 and second part 16.2

42

Seat outer part

44

spigot

46

Injection port

48

Guide inner part

50

Symmetrical axis inlet bore

52

Bore outer part 18

54

combustion chamber

d ₁

Seat diameter seat 40

d ₂

Seat diameter seat 42

d _B

Bore diameter bore 52

p _D

Pressure in the nozzle body (system pressure)

p _s

Pressure in front of injection openings 46

70

connecting channel

72

End face second part 16.2 of the multi-part inner part 16th

Claims (7)

1. Fuel injector (10) having a multi-part injection valve element (14) for injecting fuel into a combustion chamber (54) of an internal combustion engine, having an outer part (18) which is surrounded by a first pressure chamber (20) and thereby exerts pressure on the latter, and having at least one inner part (16; 16.1; 16.2) on which a pressure is exerted by a second pressure chamber (34), wherein the second pressure chamber (34) is formed by an inner contour of the outer part (18) and an outer contour of the at least one inner part (16; 16.1; 16.2), and the first pressure chamber (20) and the second pressure chamber (34) are fluidically connected to one another at all times such that system pressure p_D prevails in both pressure chambers (20; 34) at all times, and in that the at least one inner part (16; 16.1; 16.2) has at least one pressure stage (36, 38) and a seat (40) in the outer part (18), while a seat (42) of the outer part (18) is formed in the nozzle body, characterized in that, in the outer part (18), below the seat (40), there is formed a bore (52) which permits a pressure build-up below the seat (42) of the outer part (18), such that after the opening of the seat (40) of the at least one inner part (16; 16.1; 16.2), the pressure p_s builds up upstream of the injection openings (46) below the seat (42) of the outer part (18), and thus, in the outer part (18), the opening force of the outer part (18) is reduced as a function of the product of a pressure difference Δp between system pressure p_D and the pressure p_s upstream of the injection openings (46) and a surface area difference between the seat surface area of the seat (42) of the outer part (18) minus the bore surface area of the bore (52) for the seat (40) of the at least one inner part (16; 16.1; 16.2).
2. Fuel injector according to Claim 1, characterized in that the injection openings (46) are in a stellate arrangement on the combustion-chamber-side end of the nozzle body (12) and an injection of fuel takes place via said injection openings both when the at least one inner part (16; 16.1; 16.2) is open and also when the outer part (18) is open.
3. Fuel injector according to Claim 1, characterized in that the at least one inner part (16; 16.1; 16.2) and the outer part (18) are hydraulically or mechanically coupled to one another.
4. Fuel injector according to Claim 3, characterized in that the outer part (18) has a driver (28) which at least partially surrounds the inner part (16).
5. Fuel injector according to Claim 3, characterized in that the second part (16.2) of the inner part (16) has an end surface (72) which is situated opposite a connecting duct (70) in the first part (16.1) of the inner part (16).
6. Fuel injector according to Claims 4 or 5, characterized in that the outer part (18), after passing through a stroke travel (30), is opened by the at least one inner part (16; 16.1; 16.2) with a reduced opening force.
7. Fuel injector according to Claim 1, characterized in that the outer part (18) is guided on the inner part (16) of the multi-part injection valve element (14) at a guide portion (48).

Images