EP1520096B1 - Common rail injection system comprising a variable injector and booster device - Google Patents

Description

Technical area

To supply combustion chambers of self-igniting internal combustion engines, both pressure-controlled and stroke-controlled injection systems can be used. As fuel injection systems come next pump-nozzle units, pump-line-nozzle units and accumulator injection systems (common rail) are used. For example, accumulator injection systems make it possible to adjust the injection pressure to the load and speed of the internal combustion engine. Achieving high specific power and reducing emissions generally requires the highest possible injection pressure.

State of the art

For reasons of strength, the achievable pressure level in currently used accumulator injection systems (common rail) is currently limited to about 1600 bar. To further increase the pressure on accumulator injection systems, a pressure booster can be used on common-rail systems. EP 0 562 046 B1 discloses a control and valve arrangement with damping for an electronically controlled injection unit. The actuation and valve assembly for a hydraulic unit comprises an electrically energizable solenoid assembly having a fixed stator and a movable armature. The anchor has a first and a second surface. The first and second surfaces of the armature define first and second cavities, with the first surface of the armature facing the stator. It is provided a valve which is connected to the armature. The valve is capable of delivering a hydraulic actuating fluid to the injector from a sump. A damping fluid may be accumulated or drained therefrom with respect to one of the cavities of the solenoid assembly. By means of a projecting into a central bore area of a valve needle For example, the flow connection of the damping fluid can be selectively released or closed in proportion to its viscosity.

DE 101 23 910.6 relates to a fuel injection device. This is used on an internal combustion engine. The combustion chambers of the internal combustion engine are supplied with fuel via fuel injectors. The fuel injectors are acted upon by a high pressure source; Furthermore, the fuel injection device comprises a pressure booster, which has a movable pressure booster piston, which separates a connectable to the high-pressure source space from a high-pressure chamber connected to the fuel injector. The fuel pressure in the high-pressure chamber can be varied by filling a rear space of the pressure booster device with fuel or by emptying the rear space of the fuel booster from fuel.

The fuel injector includes a movable closing piston for opening or closing injection openings. The closing piston protrudes into a closing pressure chamber, so that the closing piston can be pressurized with fuel. As a result, a force acting on the closing piston in the closing direction is achieved. The closing pressure chamber and another space are formed by a common working space, wherein all portions of the working space are permanently connected to each other for the exchange of fuel.

With this solution can be achieved by controlling the booster over the rear space that the drive losses in the high-pressure fuel system compared to a control over a temporarily connected to the high-pressure fuel source working space can be significantly reduced. Furthermore, the high-pressure chamber is relieved only up to the pressure level of the high pressure accumulator chamber and not up to leak level. On the one hand this improves the hydraulic efficiency, on the other hand, a faster pressure build-up can take place up to the peak pressure level, so that the time intervals between the injection phases can be shortened.

In view of constantly increasing demands on the emission and the noise behavior of self-igniting internal combustion engines, further measures on the injection system are required in order to meet the more stringent limit values expected in the near future.

Document JP61053455 discloses a fuel injection device according to the preamble of claim 1.

Presentation of the invention

In the fuel injector with pressure booster according to the invention, a further improvement of the emission values and the noise behavior of a self-igniting Internal combustion engine can be achieved by using a Vario injector. By using a pressure booster, which acts on a nozzle space of the injection nozzle with high pressure fuel, on the one hand can achieve a very high injection pressure, on the other hand, the use of a Vario injector allows the release of different sized injection cross sections.

With a multi-part nozzle needle designed according to the invention, the injection of fuel can be realized via two different injection cross sections formed at the combustion chamber end of the fuel injector. The injection openings are favoring the atomization behavior of the fuel in an advantageous manner, procure as concentric bolt circles. At a low injection pressure, the injection of fuel takes place via an injection cross-section released by a first nozzle needle part. If the injection pressure further increased, can be injected via an additional injection cross-section, which is then released by another nozzle needle part. Via the injection cross-section released by the first nozzle needle part, a smaller quantity of fuel reaches the combustion chamber at a lower injection pressure. This favors the mixture preparation in the combustion chamber of the self-igniting internal combustion engine during a boot phase. When a presettable switching pressure is exceeded, the second nozzle needle part opens, so that, in addition to the injection cross-section released by the first nozzle needle part, by releasing a further injection cross-section at a higher pressure level, a larger quantity of fuel enters the combustion chamber of the internal combustion engine. The gas contained in the combustion chamber can be processed by a previous boot injection in a way that promotes combustion of the combustion.

The solution according to the invention allows the injection of smallest amounts of fuel with short injection periods and the injection of larger amounts of fuel over longer injection periods; If appropriate, smaller pilot injections can also be realized with the solution proposed according to the invention. Small pilot injections improve the noise performance of a self-igniting internal combustion engine. Furthermore, the use of very small pre-injection quantities into the combustion chamber of the self-igniting internal combustion engine achieves an improvement in exhaust emissions.
With the solution according to the invention, a noise improvement can be achieved in self-igniting internal combustion engines to the extent that the "nailing" can be largely prevented by the formation of the injection rate.

drawing

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

Figur 1

das Hydraulikschaltschema eines Kraftstoffinjektors mit Druckverstärker, Vario-Einspritzdüse und einer Koaxial-Düsennadel in einer ersten Ausführungsvariante nicht gemäß der Erfindung,

Figur 2

das Hydraulikschaltschema eines Kraftstoffinjektors mit Druckverstärker, Vario-Einspritzdüse und über einen Hochdruckspeicherraum direktbeaufschlagtem Schließraum in einer Ausführungsvariante nicht gemäß der Erfindung

Figur 3

die Druckverläufe im Düsenraum, Hochdruckraum und Schließraum, die Nadelhubwege und die sich entsprechend der Nadelhübe einstellenden Durchflußquerschnitte an der Düse der Ausführungsvariante eines Kraftstoffinjektors gemäß Figur 2 und

Figur 4

eine erfindungsgemäße Ausführungsvariante eines Kraftstoffinjektors mit Druckverstärker, Vario-Düse mit optimierter Führungsleckage.

It shows:

FIG. 1

the hydraulic circuit diagram of a fuel injector with pressure booster, Vario injector and a coaxial nozzle needle in a first embodiment not according to the invention,

FIG. 2

the hydraulic circuit diagram of a fuel injector with pressure booster, Vario injector and via a high-pressure storage space directly acted upon closing space in a variant not according to the invention

FIG. 3

the pressure curves in the nozzle chamber, high-pressure chamber and closing space, the Nadelhubwege and adjusting the needle strokes adjusting flow areas at the nozzle of the embodiment of a fuel injector according to Figure 2 and

FIG. 4

an inventive variant of a fuel injector with pressure booster, Vario nozzle with optimized pilot leakage.

variants

Figure 1 is the hydraulic circuit diagram of a fuel injector with pressure booster, Vario injector and coaxial nozzle needle refer to the closing space from the back space of the pressure booster from fuel can be acted upon.

The fuel injection device shown in Figure 1 comprises a fuel injector 1, which is supplied via a high-pressure accumulator chamber 2 (common rail) with fuel under high pressure. The fuel injection device contains in addition to the high-pressure accumulator 2, the fuel injector 1, a pressure booster 5, as well as designated by reference numeral 6 injection valve, via which in a here reproduced only schematically combustion chamber 7 of a self-igniting internal combustion engine at the combustion chamber end of the injection valve 6 fuel is injected into this.

Of the schematically indicated in Figure 1 high-pressure accumulator space 2 fuel passes through a first throttle point 3 and an adjoining this line 4 in a pressure chamber 11 of the booster 5. The pressure booster 5 includes in addition to the mentioned pressure chamber 11, a rear space 16. Within the booster. 5 a piston 12 is accommodated, which is designed as an axially displaceable stepped piston and comprises a first part piston 13, which is formed in comparison to a second part piston 14 with a guide enabling larger diameter. The piston 12 may consist of two separate components as well as be manufactured as one component. In the embodiment according to FIG. 1, a lug-shaped projection 15 is provided between the first partial piston 13 and the second partial piston 14. This is acted upon by a restoring spring 17 accommodated in the rear space 16, which is supported with its end opposite the projection 15 on the housing bottom of the pressure booster 5. The second partial piston 14 defines with its front side a high-pressure chamber 20 of the pressure intensifier. about which u.a. a high pressure line 28 branches off, which acts on a nozzle chamber 29 of the injection valve 6 at very high pressure fuel.

From the pressure chamber 11 of the pressure booster 5 branches off a line 18 to a magnetic valve 8 designed as a control valve, which is formed in the embodiment of the proposed fuel injection device shown in Figure 1 as a solenoid valve. In the illustrated in Figure 1 basic state, the supply line 18 from the pressure chamber 11 of the pressure booster 5 is connected to a fuel line 19 in communication, via which the rear space 16 of the booster 5 is supplied with fuel. From the rear space 16 extends in the embodiment of the fuel injection device shown in Figure 1, a return line 22 to a closing chamber 21 in the upper region of the injection valve 6. In the illustrated in Figure 1 basic state of the fuel injector pending in the high-pressure reservoir 2 pressure via the line 4 in the pressure chamber eleventh of the pressure booster 5, the solenoid valve 8, via the fuel line 19 at the rear space 16 of the booster and the return space line 22 in the closing chamber 21 of the injection valve 6 at. By way of a non-return valve 24 connected upstream of the high-pressure chamber 20, the pressure of the high-pressure reservoir 2 is present both in the high-pressure chamber 20 and in the nozzle chamber 29.

For the sake of completeness it should be mentioned that in addition to the supply line 18 from the pressure chamber 11, the fuel supply line 19 to the rear chamber 16 from the solenoid valve 8 according to the embodiment in Figure 1 a low-pressure side return 9 branches, in which a when switching the solenoid valve 8 in a further switching position, the control volume flows into a fuel tank, not shown in Figure 1.

The check valve 24, which is arranged upstream of the high-pressure chamber 20 of the pressure booster 5, comprises a closing body 26 designed here as a ball, which in turn is acted upon by a spring element 27. Instead of a check valve 24 between the high-pressure chamber 20 of the pressure booster 5 and the closing chamber 21 may - as indicated in Figure 1 - and a throttle element 24.1 be included in the line 25, which from the pressure medium, i. the fuel can be flowed through in both directions.

The injection valve 6 illustrated in the embodiment variant of the proposed fuel injection device according to FIG. 1 comprises a coaxial nozzle needle 30 which contains a first nozzle needle part 31 and a second nozzle needle part 32. The nozzle needle parts 31 and 32 are guided into each other and operated independently. The first nozzle needle part 31 is movable up and down within the housing of the injection valve 6 in the vertical direction. The stroke limit of the first nozzle needle part 31 is given by a recessed into the closing chamber 21 of the injection valve 6 annular stop 33. By means of the ring-shaped stop 33 in the closing space 21, the maximum stroke is given to the first nozzle needle part 31 and limited. Furthermore, the closing space 21 of the injection valve 6 comprises a pin-shaped stop 34, which serves as a stroke limiter for the first nozzle needle part 31 coaxially guided second nozzle needle part 32 of the coaxial nozzle needle 30. In the embodiment according to FIG. 1, a disc-shaped abutment surface 37 is formed in the upper region of the second nozzle needle part 32, which cooperates with the abutment 34 located within the closing space 21 and serves as a stroke limiter and predetermines its vertical movement within the housing of the injection valve 6 to the second nozzle needle part 32 ,

Within the closing chamber 21 of the injection valve 6 of the embodiment in Figure 1, both the first nozzle needle member 31 and the second nozzle needle member 32 are each acted upon by a spring element 38 and 39, respectively. The spring element 38 acting on the first nozzle needle part 31 is supported on an end face 36 of the first nozzle needle part 31, while the spring element 39 surrounding the pin-shaped stop 34 rests against the end face 37 of the second nozzle needle part 32. The closing space 21 shown in FIG. 1 is supplied with fuel from the rear space 16 of the pressure booster 5 via the return space line 22, wherein the return space line 22 may contain a throttle point 23 in the region of its mouth in the closing space 21. The opening from the check valve 24 in the closing chamber 21 line 25 may open into the closing chamber 21, wherein instead of integrated in Figure 1 in the line 25 check valve 24 and the throttle element indicated in Figure 1 24.1 in the line 25 between the high-pressure chamber 20 of the pressure booster. 5 and the closing space 21 can be inserted.

The illustrated in Figure 1 first nozzle needle member 31 of the coaxial nozzle needle 30 comprises a hydraulically effective surface 35 which is formed in the illustrated embodiment as a pressure shoulder 35 tapered. The pressure shoulder 35 on the outer peripheral surface of the first nozzle needle part 31 is completely enclosed by the nozzle chamber 29 of the injection valve 6. From the nozzle chamber 29 of the injection valve 6, an annular gap 50 extends to the combustion chamber end of the injection valve 6. The second nozzle needle member 32 also includes a hydraulically effective surface 40 in the form of a pressure shoulder, which is formed at the combustion chamber end of the second nozzle needle portion 32. According to the design of the hydraulically effective surface 40 at the combustion chamber end of the second nozzle needle member 32 and the design of the second nozzle needle member 32 acting spring element 39, a switching pressure can be adjusted according to the dimensions, in which the inner nozzle needle portion 31 of the coaxial nozzle needle 30 as shown in FIG 1 opens.

At the combustion chamber end of the injection valve 6, a conical surface 44 is formed, are formed on the injection openings. In the embodiment variant of the injection valve 6 of the fuel injection device according to FIG. 1, the nozzle of the injection valve 6 designed as a vario injection nozzle 41 comprises a first injection cross section 42 and a further, second injection cross section 43. In a preferred embodiment of the solution, the first injection cross section 42 and the second injection cross section 43 are formed as rows of holes, for example as a concentric hole circles, and contain a variety of smallest holes, which during the injection of fuel into the combustion chamber 7 - here only schematically reproduced - a fine atomization of the fuel during the injection process is achieved, which in turn a favorable combustion process in terms the emission levels and the noise level. According to the embodiment in Figure 1, the first injection section 42 is released when opening the first nozzle needle member 31 upon application of the nozzle chamber 29 at high pressure. Depending on the dimensioning of the hydraulically effective surface 40- here designed as a pressure shoulder - and depending on the dimensions of the second nozzle needle part 32 beauf beating spring element 39, opens the second nozzle needle portion 32 of the coaxial nozzle needle 30 at a certain switching pressure and are in addition to the first injection section 42, the further, second injection section 43 free. In this switching state-both nozzle needle parts 31 and 32 open-fuel is injected both via the first injection cross-section 42 and additionally via the second, second injection cross-section 43 released by the first nozzle needle part 31 into the combustion chamber 7 of the self-igniting internal combustion engine.

The adjusting at the high pressures guide leakage due to the nested needle nozzle parts 31 and 32 of the coaxial nozzle needle 30 via a recess 48, which may be formed, for example, as an annular groove to the outer periphery of the second nozzle needle member 32 via a channel 47, which the first nozzle needle member 31st penetrated, promoted in a surrounding this further annular groove 46, which in turn is on the housing side with a leakage oil passage 49 in communication. Accordingly, the guide leakage can be discharged via the leak oil line 49 into the low-pressure region of the fuel injection system analogously to the low-pressure-side return 9, which is assigned to the solenoid valve 8.

While the hydraulically effective surface 35 is enclosed on the outer circumference of the first nozzle needle part 31 from the nozzle chamber 29, the hydraulic surface 40, formed as a pressure shoulder, the second nozzle needle part 32 closing space is formed on the one hand by the end face 45 of the first nozzle needle member 31 and on the other hand by the conical in the combustion chamber 7 of the self-igniting internal combustion engine projecting nozzle body surface 44 of the injection valve. 6

The mode of operation of the embodiment variant shown in FIG. 1 is as follows. Via line 4, the pressure prevailing in the high-pressure reservoir 2 is applied to the fuel injector 1. In the illustrated in Figure 1 basic state, the solenoid valve 8 is not activated and there is no injection instead. The pending in the high-pressure reservoir 2 pressure is therefore in the pressure chamber 11 of the booster 5 and the aforementioned solenoid valve 8. Furthermore, the pending in the high-pressure accumulator 2 pressure on the through-connected solenoid valve 8 and the fuel line 19 in the rear chamber 16 of the booster 5 at. Further, the rail pressure is on the return space line 22 and the throttle body 23 received in this in the closing chamber 21 of the injection valve 6 and flows from the closing chamber 21 of the injection valve 6 in the release direction of the check valve 24 in the high pressure chamber 20 of the booster 5 over. From the high-pressure chamber 20 of the pressure booster 5, in turn, the fuel flows via the high-pressure line 28 into the nozzle chamber 29 of the injection valve 6. In the normal state, therefore, all the pressure chambers 11, 16 and 20 of the pressure booster 5 are acted upon by the pressure level prevailing in the high-pressure reservoir 2, wherein the partial pistons 13 and 14 of the pressure booster 5 are pressure-balanced. In this basic state of the system shown in Figure 1, the pressure booster 5 is deactivated and there is no pressure amplification. In this state, the piston 12 of the pressure booster 5 is placed on its associated return spring 17 in its initial position, with a filling of the high-pressure chamber 20 of the booster 5 via the check valve 24 from the closing chamber 21 of the injection valve 6 is made. Due to the pending in the closing chamber 21 pressure is a hydraulic closing force the nozzle needle parts 31 and 32 of the coaxially formed nozzle needle 30 is constructed. In addition, the first nozzle needle part 31 and the second nozzle needle part 32 are acted upon via the closing elements 21 arranged in the spring elements 38 and 39 in the closed position. Therefore, the pressure level present in the high-pressure accumulator 2 can constantly be present in the nozzle chamber 29 of the injection valve 6 via the high-pressure line 28, without the first nozzle needle part 31 opening onto the pressure shoulder 35 due to the pressure effect of the fuel. Only when the pressure in the nozzle chamber 29 rises above the high-pressure reservoir 2 prevailing pressure, which takes place by connecting the booster 5, opens the first nozzle needle member 31 and the injection begins.

This is achieved in that the solenoid valve 8 is activated and thereby flows from the rear space 16 via the fuel line 19 fuel in the low-pressure side drain 9, so that the rear space 16 of the pressure booster 5 is cut off from the system pressure supply. Because of this, the pressure in the rear chamber 16 of the booster 5 drops, causing the pressure booster 5 is activated and the pressure in the nozzle chamber 29 increases because the activated pressure booster 5 causes an increase in the pressure in the high-pressure chamber 20 through which the nozzle chamber 29 is supplied with fuel , As a result, on the hydraulic surface 35 of the first nozzle needle part 31 - here formed as a pressure shoulder - one of the spring force 38 counteracting opening force, so that the first nozzle needle part 31 auffährt in a vertical upward direction. The high pressure is in the nozzle chamber 29 as long as the back space 16 is relieved of pressure via the switched solenoid valve 8 in the low-pressure side 9. Due to the pressure relief of the back space 16 and the closing chamber 21 of the injector 6 is relieved via the line 22 in the rear space 16 of the booster 5, which in turn is relieved via the aforementioned line 19 to the low pressure side 9 of the fuel injection system. As long as the rear space 16 of the booster 5 is drukkentlastet, the pressure booster 5 remains activated and compresses the fuel in the high-pressure chamber 20. The compressed fuel is passed through the nozzle chamber 29 along the annular gap 50 to the first injection section 42, due to the vertical movement on the first Düsennadelteils 31 is released, so that the inflowing over the annular gap 50 fuel is injected via the first injection section 42 into the combustion chamber 7 of the self-igniting internal combustion engine. Due to the pressure relief of the rear space 16 of the pressure booster 5, the closing chamber 21 of the injection valve 6 is pressure relieved.

In this state, ie with the first nozzle needle part 31 open and fuel injection via the first injection cross section 42, the injection pressure is likewise at the needle tip of the second nozzle needle part 32, which is coaxial in the first nozzle needle part 31 is guided. As a result, an opening pressure force acts on the pressure surface formed as a hydraulic shoulder 40 at the tip of the second nozzle needle part 32. Since the closing chamber 21 of the injection valve 6 is relieved of pressure acts on the second nozzle needle member 32 as a closing force, the spring element 39. About the dimensioning of the pressure shoulder 40 am the combustion chamber side end of the second nozzle needle member 32 and the spring 39, a switching pressure can be adjusted, from which the coaxially guided in the first nozzle needle part 31 second nozzle needle member 32 opens and this associated further, second injection section 43 releases. Accordingly, at a pressure level below the adjustable switching pressure of the second nozzle needle part 32, both the first nozzle needle part 31 can be opened and thereby the first injection cross section 42 can be released, while the second nozzle needle part 32 remains closed. In this state, an injection of fuel via the first injection cross-section 42. At above the adjustable switching pressure lying injection pressure open both the first nozzle needle member 31 and the second nozzle needle member 32, since the biasing spring force is smaller than the hydraulic force at the combustion chamber end , that is, on the pressure shoulder 40 of the second nozzle needle part 32, acts on this. Above the adjustable switching pressure, injection takes place both via the first injection cross-section 42 and via the further, second injection cross-section 43 into the combustion chamber 7 of the self-igniting internal combustion engine.

To end the injection, the solenoid valve 8 is switched, so that the rear space 16 of the pressure booster 5 and the closing chamber 21, connected to the rear space 16 via the line 22, are separated from the low pressure side 9 of the solenoid valve 8. As a result, the return chamber 16 is acted upon via the supply line 18 from the pressure chamber 11 of the pressure booster 5 with the pressure level prevailing in the high-pressure storage space 2, so that the rail pressure level builds up again in the rear space 16. Due to this, the pressure in the high-pressure chamber 20 of the pressure booster 5 decreases to the pressure level prevailing in the high-pressure reservoir 2. Since in the closing chamber 21 of the injection valve 6, the pressure level prevailing in the high-pressure reservoir 2 is now also present, both the first nozzle needle part 31 and the second nozzle needle part 32 of the coaxial nozzle needle 30 are pressure-balanced. Due to the loading of the first nozzle needle part 31 and the second nozzle needle part 32 with spring elements 38 and 39, the nozzle needle parts 31, 32 of the coaxial nozzle needle 30 are placed in their closed position. Then the injection is finished. The closing speed, with which the first nozzle needle part 31 and the second nozzle needle part 32 are pressed into their closed positions, can be influenced via the inlet throttle 23, which is received in the return chamber line 22 from the rear space 16 to the closing space 21 of the injection valve 6. After the induced pressure equalization, the piston 12, comprising a first sub-piston 13 and a sub-piston 14, in one-piece or in a separate embodiment by the return spring 17 returned to its original position. In order to dissipate leakage flows through the needle guides, a relief 46, 47, 48 in a leak oil line 49 is provided on the coaxial nozzle needle 30 according to the embodiment in FIG. 1, via which the guide leak can be discharged into the low-pressure region of the fuel injection system.

The illustration according to FIG. 2 shows the hydraulic circuit diagram of a fuel injector with a pressure booster, a Vario injection nozzle and a closing space of an injection valve of the fuel injector which can be directly acted upon via a high-pressure reservoir.

The variant shown in Figure 2 differs from the variant shown in Figure 1 in that the closing chamber 21 of the injector 6 via a branching off from the line 4 Hochdruckabzweig 60 directly bypassing the solenoid valve 8 and the rear chamber 16 of the booster 5 with the in the high-pressure reservoir 2 pending pressure level can be acted upon. Another difference from the embodiment of Figure 1 is that according to the embodiment shown in Figure 2, only the first nozzle needle member 31 of the coaxial nozzle needle 30 is acted upon by acting as a closing spring spring element 38 on the end face 36. Incidentally, the embodiment shown in Figure 2 is identical to the embodiment which has already been described in connection with Figure 1.

In the basic state shown in Figure 2, the solenoid valve 8, which may be formed as a piezoelectric actuator or may be designed as a direct-operated valve or servo valve, switched so that the pressure in the space 11 of the booster 5 pending pressure corresponding to the pressure in the high-pressure reservoir 2 , via the fuel line 19 in the rear space 16 is present. Furthermore, the pressure level in the high-pressure reservoir 2 via the line 4 to the branch 60 in the closing chamber 21 of the injection valve 6. About the outgoing from the closing chamber 21 check valve line 25, the high-pressure chamber 20 of the pressure booster 5 with rail pressure level, i. the pressure level, which prevails in the high-pressure accumulator space 2, acted upon. Furthermore, via the high-pressure line 28, which starts from the high-pressure chamber 20 of the pressure booster 5, the pressure level prevailing in the high-pressure reservoir 2 is also present in the nozzle chamber 29 of the injection valve 6.

The metering of the fuel to the combustion chamber end of the injection valve 6 is effected by a pressure relief of the back space 16 of the pressure booster 5 by activating the example designed as a 3/2-way valve solenoid valve 8. The back space 16 is thereby separated from the Systemdruckbeaufschlagung and the low pressure line 9, which emanates from the solenoid valve 8, connected. As a result, the pressure drops in the rear chamber 16, whereby the pressure booster 5 is activated, ie the piston 12 moves due to the pressure prevailing in the pressure chamber 11, the pressure level of the high pressure accumulator chamber 2 corresponding pressure down, whereby the pressure in the high pressure chamber 20 and the high pressure line 28 also in the control chamber 29 of the injection valve 6 increases. This increases the hydraulic force acting on the first nozzle needle part 31, ie its pressure shoulder 35, and the nozzle needle 31 moves upward in the vertical direction, but within the closing space 21 of the injection valve 6 there is provided a stroke limiter 33 which determines the maximum vertical stroke of the first nozzle needle part 31 limited. The first nozzle needle part 31 is designed so that its opening occurs when in the nozzle chamber 29, a first opening pressure p _{ö, 1 is} reached. As long as the rear space 16 of the pressure booster 5 remains depressurized, the pressure booster 5 is activated. The pressure in the nozzle chamber 29 and at the needle tip of the second nozzle needle part 32 is increased in the further course of the injection up to a maximum pressure level p _max . If the level of the injection pressure reaches a second opening pressure p _{ö, 2} , the second nozzle needle part 32 opens, whereby the further, second injection cross section 43 is opened and now an injection of fuel into the combustion space 7 of the self-igniting internal combustion engine via both the first injection cross section 42, the one from first nozzle needle part 31 is released, as well as via the further, second injection cross-section 43 takes place, which is released by the second nozzle needle part 32. The first opening pressure p _{ö, 1} is essentially determined by the hydraulically effective surfaces, ie the design of the pressure shoulder 35 in the nozzle chamber 29, as well as the dimensioning of the end face 36 of the first nozzle needle member 31 and thus directly proportional to the pressure prevailing in the high-pressure reservoir 2 pressure level. The second opening pressure p _{ö, 2} is also essentially determined by the hydraulic pressure surface 40 at the needle tip of the second nozzle needle part 32 and the dimensioning of the end face 37, which assigns the closing space 21 of the injection valve 6. Also, the second opening pressure p _{ö, 2} is proportional to the pressure prevailing in the high-pressure accumulator 2 pressure level.

To terminate the injection, the return space 16 of the pressure booster 5 is pressurized by the solenoid valve 8 with system pressure, i. the high-pressure accumulator 2, connected.

Due to the building up in the back space 16 via the lines 19 and 18 pressure of the piston 12 of the booster 5, supported by the return spring 17, moves into its initial position, whereby the pressure in the high-pressure chamber 20 of the booster 5 decreases. Because of this, the pressure in the nozzle chamber 29 of the injection valve 6 drops to the rail pressure level, ie the pressure level in the high-pressure reservoir 2, whereby the first nozzle needle part 31 and the second nozzle needle part 32 are hydraulically balanced. Due to the application of the first nozzle needle part 31 by the spring element 38 within the closing space 21 of the injection valve 6, this is closed. The injection is stopped. As a result, the pressure force built up at the needle tip of the second nozzle needle part 32 collapses, so that the second nozzle needle part 32 is closed due to the pressure level established in the closing space 21 via the lines 4 and 60, respectively. The closing speed can be influenced by the dimensioning of the throttle point 23, which is pre-connected to the closing space 21 and received in the branch 60.

Also in the embodiment according to Figure 2 is formed on the coaxially formed nozzle needle 30 between the nested needle nozzle parts 31 and 32, the guide leakage absteuernde, designed as annular grooves recesses 46 and 48, for example, which are in communication with a drain line 49, which the discharged guide leakage for example, returns to a fuel tank, not shown here.

Also in the embodiment according to FIG. 2, the piston 12 of the pressure intensifier 5 can be designed in one or in several parts. The return spring 17, which is received in the rear space 16 of the booster 5, can be arranged both in the pressure chamber 11 of the booster 5 and in the high-pressure chamber 12 of the booster 5.

FIG. 3 shows the pressure curves in the nozzle chamber, high-pressure chamber and in the closing space as well as the needle stroke movement and the flow cross-sections corresponding to the needle stroke paths on the vario nozzle of the embodiment according to FIG.

At a time t ₁ , the rail pressure level p _rail is present in the high-pressure reservoir 2. At a second time, characterized by t ₂ , the first opening pressure p _{ö, 1 is} reached, so that the first nozzle needle part 31 opens due to the force acting in the control chamber 29 on the pressure shoulder 35 of the first nozzle needle member 31 hydraulic force. At the first injection cross-section, which is released by the opening movement of the first nozzle needle part 31, a first injection quantity 74 sets, which arrives during the opening phase between t ₂ and t _{3 of} the first nozzle needle part 31 in the combustion chamber 7 of the self-igniting internal combustion engine. In parallel with the pressure increase in the nozzle chamber 29 or in the high-pressure chamber 20 of the pressure booster 5 (see short train 70), the pressure in the rear chamber 16 of the pressure booster 5 drops according to the curve 71. If, during the further pressure rise 70 _, the switching pressure of the second nozzle needle part 32 is reached from the first opening pressure p _{o, 1} to the second opening pressure p _{o, 2} , this opens at a time t ₃ (see the lowermost diagram in FIG. To the Switching time t ₃ remains the first nozzle needle part 31 due to the force in the nozzle chamber 29 on the hydraulic surface 35, ie the pressure shoulder, acting hydraulic force in its open position according to the marked with reference numeral 72 Hubverlaufes and assumes its maximum stroke h _max , which by the Closing space 21 formed stop 33 is limited. At the switching time t ₃ opens due to the exceeding of the second opening pressure p _{ö, 2,} the second nozzle needle part 32 according to the marked with reference numeral 73 Hubverlaufes. As a result, the amount of fuel injected into the combustion chamber 7 of the self-igniting internal combustion engine increases according to the quantity indicated by reference numeral 75, ie, in addition to the first injection cross section 42, released by the first nozzle needle part 31, an injection of fuel into the combustion chamber 7 of the internal combustion engine takes place via the first injection cross-section 42 as well as over the other, second injection cross-section 43, which is now released due to the lifting movement of the second nozzle needle part 32. At time t ₄ , the back space 16 of the booster 5 is again connected to the system pressure by means of the solenoid valve 8, so that a pressure reduction in the control chamber 29 and in the high-pressure chamber 20 of the booster 5 adjusts according to a pressure build-up in the back space 16 and therefore, as above described, the forces acting on the first nozzle needle portion 31 and the second nozzle needle member 32 opening forces on the hydraulic surfaces 35 and 40 and the closing forces in the closing chamber 21 closing forces, ie the first nozzle needle member 31 acting spring, and in the closing space 21 on the Lines 4 and 60 pending pressure level of the first nozzle needle member 31 is transferred to its closed position, whereby the injection finds its end.

FIG. 4 shows an embodiment variant of a fuel injector with pressure booster and vario-injection nozzle with optimized pilot leakage.

The embodiment variant shown in FIG. 4 shows that a regulated high-pressure delivery unit 81 delivers fuel from a fuel tank 80 into a high-pressure storage space 2. From the high-pressure accumulator 2 from the high-pressure fuel via a throttle point 3 containing line 4 in the pressure chamber 11 of the booster 5 at. From the line 4 branches off in front of the pressure chamber 11 from a line 18, via which the solenoid valve 8 is acted upon. From the solenoid valve 8 from the pressure level of the high-pressure accumulator 2 is in the switching position shown in Figure 4 in the rear space 16 of the booster 5, in which analogous to the embodiments shown in Figure 1 and 2 of the invention proposed solution, a return spring 17 is added. The return spring 17 is supported on the housing side in the rear space 16 of the booster 5 and acts on a diameter enlarged first part piston 13 of a two-part piston 12, which with his second sub-piston region 14 a high-pressure chamber 20 - analogously to the illustrations according to Figures 1 and 2 - acted upon.

From the solenoid valve 8 branches off analogously to the illustration according to Figures 1 and 2, a low-pressure side return 9, which opens into the fuel tank 80. The check valve 24, via which a filling of the high-pressure chamber 20 of the pressure intensifier 5 - assuming a corresponding switching position of the solenoid valve 8 shown in FIG. 4 - takes place in a branch from the fuel line 19 to the rear chamber 16 received the booster 5.

The injection valve 6 according to the embodiment in Figure 4 comprises a coaxial nozzle needle 30 having a first nozzle needle portion 31 and a further, inner nozzle needle portion 32. The inner, second nozzle needle part 32 of the coaxial nozzle needle 30 is associated with a separately pressure-relieving nozzle spring chamber 83 which is depressurized via interposition of a throttle point 86 in the low pressure lines 9 and from there into the fuel tank low pressure side. Via a further throttling point 85 containing supply line from the high pressure line 19 to the rear space 16, a first nozzle spring chamber 82, which acts on the first nozzle needle part 31, filled.

A sleeve-shaped body 89 with a shoulder serves to seal the second nozzle control chamber 83 with respect to the first nozzle control chamber 82. The sleeve-shaped body 89 has a high pressure-tight guide relative to the second nozzle needle part 32 and a flat sealing seat with respect to the injector body. The sleeve-shaped body 89 may be pressurized from the first nozzle control chamber 82, which acts vertically upward to produce an additional sealing force.

To a coaxial with the first nozzle needle member 31 arranged sleeve-shaped body 89, both the first spring element 38 and the second spring element 39 is supported. The spring element 39 assigned to the second nozzle needle part 32 acts on a stop 87 formed on the circumference of the second nozzle needle part 32, while the spring element designated by reference numeral 38 acts directly on the end face 36 of the first, outer nozzle needle part 31. The second nozzle needle part 32 is provided for discharging the guide leakage with a longitudinal bore 84, via which a recess 48 provided on the outer circumference of the second nozzle needle part 32 is in communication with the second nozzle spring chamber 83 which can be depressurized on the low-pressure side.

In the basic state shown in FIG. 4, the pressure level prevailing in the high-pressure reservoir 2 lies in the pressure chamber 11 of the pressure booster 5 on the solenoid valve 8 the line 19 in the rear space 16 of the pressure booster 5 in the first nozzle spring chamber 82 of the injection valve 6 and via the check valve 24 in the high-pressure chamber 20 of the pressure booster 5 and in over the fuel supply line 28 can be acted upon by high pressure nozzle chamber 29 of the injector. The pressure-relieving second nozzle spring chamber 83 above the end face 37 of the second nozzle needle part 32 is connected via the throttle point 86 and the discharge line 88, bypassing the solenoid valve 8 directly to the return line 9 in the fuel tank 80 of the fuel injection system. In the illustrated in Figure 4 basic state of the pressure booster 5 is not active, ie there is no pressure gain instead. By the return spring 17, the piston 12 is returned to its original position. A filling of the high-pressure chamber 20 takes place in the direction of penetration of the check valve 24 against the closing element 26, which is acted upon by a spring element 27 within the check valve 24 and is fed through the line 19 between the solenoid valve 8 and the back space 16 of the pressure booster 5. Due to the pressure in the first nozzle spring chamber 82 which corresponds to the pressure prevailing in the high-pressure reservoir 2, a hydraulic closing force is exerted on the first nozzle needle part 31, ie the outer part of the coaxial nozzle needle 30. In addition, a closing spring force acts on the first nozzle needle part 31 and the other, second nozzle needle part 32 via the spring elements 38 and 39 respectively. For this reason, the pressure level prevailing in the high-pressure reservoir 2 can always be present in the nozzle chamber 29 without an opening of the first nozzle needle part 31 sets. Only when the pressure within the nozzle chamber 29 rises above the pressure level of the high-pressure reservoir 2, which is achieved by connecting the pressure booster 5, does the first nozzle needle part 31 open and the injection begins.

In this case, the metering of the fuel by the pressure relief of the back space 16 is analogous to the embodiments in Figures 1 and 2. This is done by a circuit of the example designed as a 3/2-way control valve solenoid valve 8. It is a separation of the back space 16 of Pressure booster 5 and the system pressure, ie the pressure prevailing in the high-pressure accumulator 2 pressure level, and a connection of the back space 16 with the return line 9 to the fuel tank 80, ie with the low pressure side. The pressure in the rear chamber 16 drops, whereby the pressure booster 5 is activated and an increase in the pressure level in the high-pressure chamber 20, an increase in the pressure in the nozzle chamber 29, which in turn acts on the hydraulic surface 35 of the first nozzle needle member 31 and its Auffahrbewegung against the spring force causes the spring element 38 in the opening direction. As long as the rear space 16 of the pressure booster 5 is depressurized, the pressure booster 5 remains activated and compresses the fuel in the high-pressure chamber 20. The compressed fuel flows from there to the nozzle needle, ie the nozzle chamber 29, and from there via the annular gap 50 in the direction of the combustion chamber end the first and second nozzle needle parts 31 and 32, respectively. The first one Nozzle spring chamber 82 remains relieved of pressure, but at the needle tip of the second nozzle needle part 32, an injection pressure level builds up. As a result, a pressure force acting on the hydraulically effective surface 40 (pressure shoulder) in the opening direction of the second nozzle needle part 32 adjusts at the tip of the second nozzle needle part 32. Since the second nozzle spring chamber 83 associated with the second nozzle needle part 32 is still relieved of pressure, follows as closing force on the second nozzle needle member 32, the spring elements 39. About a suitable dimensioning of the pressure shoulder 80 with respect to the closing force of the spring element 39 can be analogous to the representation of the embodiment set according to Figure 1, a switching pressure, from which the internally guided in the coaxial nozzle needle 30 second nozzle needle part 32 opens. At low injection pressure below the adjustable switching pressure, the first nozzle needle part 31 opens, while the second nozzle needle part 32 remains closed. Accordingly, injection takes place via the first injection cross-section 42. As the injection pressure continues to rise above the switching pressure of the second nozzle needle part 32, the second nozzle needle part 32 opens in addition to the already open first nozzle needle part 31, whereby an injection into the combustion chamber 7 of the internal combustion engine both via the first injection cross-section 42 also takes place via the further, second injection cross section 43.

The termination of the injection is effected by means of the solenoid valve 8, via which the rear space 16 of the pressure booster 5 and the first nozzle spring chamber 82 separated from the return side 9 of the solenoid valve 8 and with the supply pressure, i. be connected to the pressure prevailing in the high-pressure reservoir 2 pressure level. Thus, the pressure level prevailing in the high-pressure reservoir 2 builds up in the rear space 16, whereby a pressure relief in the high-pressure chamber 20 of the pressure booster 5 is set to the rail pressure level. Since in the first nozzle spring chamber 82 is also the rail pressure level is present, the first nozzle needle member 31 is now balanced in terms of hydraulic forces and is actuated only by the spring force of the spring element 39, i. closed. Due to the interrupted fuel supply to the second nozzle needle part 32, the pressure level below the needle tip of the second nozzle needle part 32 drops very rapidly, i. the second nozzle needle part 32 begins to close due to the action of the spring force of the spring element 38. Thus, the injection is completed. The self-adjusting closing speed with respect to the second nozzle needle part 32 can be influenced by the design of the throttle bodies 85 and 86, respectively.

To avoid leakage flows through the nozzle holes, a relief line in the form of a bore 84 is guided through the second nozzle needle part 32, which extends from a recess 48 into the second nozzle control chamber 83. According to the embodiment shown in Figure 1, the following three Führungsleckageströme set in the idle state, ie at applied rail pressure level in the closing chamber 21 and the nozzle control chamber 29 on. Between the injector body, ie its brennraumseitigem part, and the first nozzle needle part 31, which is formed in Durclunesser d ₁ , a first Führungsleckagestrom arises between the nozzle chamber 29 and Leckölnut 46 and a Führungsleckagestrom between closing space 21 and Leckölnut 46, while between the first On the other hand, the nozzle needle part 31 and the second nozzle needle part 32 arranged internally in FIG. 1 sets a further guide gap which flows out into the leak oil line 49 via the leakage oil groove 48 which is formed on the inner part of the coaxial nozzle needle 30. The second nozzle needle part 32 is formed in a diameter d ₂ , which may be between 2 to 2.5 mm, while the first nozzle needle part 31 is formed in an outer diameter d ₁ , which may be between 4 and 4.5 mm. There are thus two guide leakage flows on a large diameter d ₁ and a guide leakage flow on a small diameter d ₂ . 4, between the second nozzle needle part 32 and the first nozzle needle part 31 surrounding it, a leakage oil groove 48 is likewise received in an analogous manner, which communicates with the longitudinal bore 84, via which the leak oil can be removed. There occurs a first pilot leakage flow with a small diameter d ₁ between the nozzle chamber 29 and Leckölnut 48. Furthermore, a second pilot leakage flow with a small diameter d _{2 occurs} between the nozzle control chamber 82 and the leak oil groove 48. Due to the smaller diameter of the second nozzle needle part 32 of 2 to 2.5 mm can be achieved with this embodiment, a significant reduction of previous leakage oil volume flows into the leak.

LIST OF REFERENCE NUMBERS

1

fuel injector

2

High-pressure accumulator

3

first throttle point

4

management

5

booster

6

Injector

7

Combustion chamber internal combustion engine

8th

Solenoid valve (3/2-way valve)

9

low-pressure side return

10

Housing pressure booster

11

pressure chamber

12

piston

13

first part piston

14

second partial piston

15

Approach second partial piston

16

backcourt

17

Return spring

18

Supply line solenoid valve

19

Fuel line rear space

20

High-pressure chamber

21

closing chamber

22

Return room line to the closing room

23

second throttle point

24

check valve

24.1.

restriction

25

Check valve line

26

closing element

27

Spring element of the check valve

28

High pressure line nozzle space

29

nozzle chamber

30

coaxial nozzle needle

31

first nozzle needle part

32

second nozzle needle part

33

Stroke stop for first nozzle needle part

34

Stroke limit for second nozzle needle part

35

Pressure shoulder first nozzle needle part

36

End face of the first nozzle needle part

73

Stroke course second nozzle needle part

37

Face second nozzle needle part

38

Spring element first nozzle needle part

39

Spring element second nozzle needle part

40

Pressure shoulder second nozzle needle part

41

Vario injection nozzle

42

first injection cross section

43

second injection cross section

44

combustion chamber side area injector housing

45

End face of the first nozzle needle part

46

Leckölnut first nozzle needle part

47

Leakage channel

48

Leckölnut second nozzle needle part

49

Drain line

50

annular gap

60

High-pressure branch from the high-pressure reservoir 2

70

Pressure curves nozzle chamber / high pressure chamber

71

Pressure gradient backspace

t ₁

control time

t ₂

control time

t ₃

control time

t ₄

control time

72

Stroke course first nozzle needle part

74

first flow area

75

second flow area

80

Fuel tank

81

regulated high pressure pumping unit

82

first nozzle control room

83

second nozzle control room

84

longitudinal bore

85

Throttle first nozzle control room

86

Throttle second nozzle control chamber

87

needle-side stop

88

Relief lines return

89

sleeve-shaped body

Claims (24)

1. Fuel injection device for internal combustion engines, with a fuel injector (1) capable of being supplied from a high-pressure fuel source (2, 81), there being arranged between an injection valve (6) and the high-pressure fuel source (2, 81) a pressure intensifier (5) having an intensifier piston (12) which separates a pressure space (11) connectable to the high-pressure fuel source (2, 81) from a high-pressure space (20) acting upon a nozzle space (29) of the fuel injector (1), a pressure change in a back space (16) at the pressure intensifier (5) bringing about a pressure change in the high-pressure space (20), and the injection valve (6) comprising a nozzle needle (30), by means of which the injection orifices pointing towards a combustion space (7) can be opened or closed, the nozzle needle (30) comprising a first nozzle-needle part (31) and a further nozzle-needle part (32) which at an injection nozzle (41) open and close different injection cross sections (42, 43) activatably as a function of pressure, characterized in that the nozzle-needle parts (31, 32) of the nozzle needle (30) are guided one in the other, and in that the first nozzle-needle part (31) and the second nozzle-needle part (32) can be acted upon by fuel pressure, counter to the action of closing springs (38, 39), via a first nozzle control space (82) capable of being acted upon by fuel pressure, with a throttle point (85) being interposed.
2. Fuel injection device according to Claim 1, characterized in that the nozzle-needle parts (31, 32) of the nozzle needle (30) have faces (35, 40) allowing hydraulic pressure actuation.
3. Fuel injection device according to Claim 2, characterized in that the first nozzle-needle part (31) comprises a pressure shoulder (35) which can be actuated via the fuel which enters a nozzle space (29) and which is under high pressure.
4. Fuel injection device according to Claim 2, characterized in that the second nozzle-needle part (32) comprises a pressure shoulder (40) which is arranged at its end located on the combustion-space side.
5. Fuel injection device according to Claim 2, characterized in that a hydraulic space actuating the second nozzle-needle part (32) via a pressure shoulder (40) is delimited by an end face (45) of the first nozzle-needle part (31) and by a nozzle-body face (44) located on the combustion-space side.
6. Fuel injection device according to Claim 5, characterized in that the nozzle-body face (44) located on the combustion-space side is of conical design.
7. Fuel injection device according to Claim 5, characterized in that the hydraulic space surrounding the pressure shoulder (40) of the second nozzle-needle part (32) is acted upon by fuel from the nozzle space (29) via an annular gap (50) when the first nozzle-needle part (31) is actuated in the opening direction.
8. Fuel injection device according to Claim 1, characterized in that the first nozzle-needle part (31) and the second nozzle-needle part (32) are assigned stroke-limiting stops (33, 34) arranged in a closing space (21), at least one of the nozzle-needle parts (31, 32) being acted upon by a closing-spring element (38, 39).
9. Fuel injection device according to Claim 1, characterized in that the first nozzle-needle part (31) opens and closes a first injection cross section (42) and the second nozzle-needle part (32) opens and closes a second injection cross section (43).
10. Fuel injection device according to Claim 9, characterized in that, after the opening of a first injection cross section (42) by the first nozzle-needle part (31), in the case of the pressure-dependent actuation of the second nozzle-needle part (32) a second injection cross section (43) is opened in addition to the first injection cross section (42).
11. Fuel injection device according to Claim 9, characterized in that the first and the second injection cross section (42, 43) are designed as concentric hole circles at that end of a nozzle body (44) of the fuel injector (1) which is located on the combustion-space side.
12. Fuel injection device according to Claim 1, characterized in that the first nozzle-needle part (31) of the second nozzle-needle part (32) have in each case, on their circumference, recesses (46, 48) which discharge leakage oil.
13. Fuel injection device according to Claim 12, characterized in that the recesses (46, 48) which discharge leakage oil are connected via a leakage-oil duct (47) provided in one of the nozzle-needle parts (31, 32) and issue into a housing-side leakage-oil line (49).
14. Fuel injection device according to Claim 1, characterized in that the pressure intensifier (5) contains a pressure space (11) which is acted upon by the high-pressure fuel source (2, 81) via a line (4) and which has a back space (16) which is connected by lines (18, 19) to the high-pressure fuel source (2, 81) via a solenoid valve (8) and which comprises a high-pressure space (20) which acts with high pressure upon the nozzle space (29) surrounding the coaxial nozzle needle (30).
15. Fuel injection device according to Claim 14, characterized in that the back space (16) of the pressure intensifier (5) is connected to a closing space (21) of the injection valve (6).
16. Fuel injection device according to Claim 14, characterized in that the closing space (21) of the injection valve (6) is acted upon directly with pressure by the high-pressure fuel source (2, 81) via a line (4, 60).
17. Fuel injection device according to Claim 15, characterized in that the closing space (21) of the injection valve (6) is acted upon with pressure, parallel to a line (22), by the back space (16) or, parallel to a line (60), by the high-pressure fuel source (2, 81) via a line (25) containing a non-return valve/throttle point (24) and fed by the high-pressure space (20).
18. Fuel injection device according to Claims 1 and 15 to 17, characterized in that, with the valve (8) deactivated, a flow connection (4, 18, 19, 22; 60, 23, 85) from the high-pressure source (2, 81) to the closing space (21, 82) is made.
19. Fuel injection device according to Claims 1 and 15 to 17, characterized in that, with a valve (8) deactivated, a flow connection (4, 18, 19, 22; 60, 23, 85, 25, 28) from the high-pressure source (2) to the nozzle space (29) is made.
20. Fuel injection device according to Claim 5, characterized in that at least the first nozzle-needle part (31) can be acted upon by means of a pressure capable of being generated in the closing-pressure space (21, 82).
21. Fuel injection device according to Claim 1, characterized in that the second nozzle-needle part (32) can be actuated, independently of this, via a pressure relief of a second nozzle control space (83).
22. Fuel injection device according to Claim 21, characterized in that the second nozzle control space (83) is sealed off from the nozzle control space (82) by means of a sleeve-shaped body (89).
23. Fuel injection device according to Claim 21, characterized in that the second nozzle-needle part (32) contains a longitudinal duct (84), via which guide leakage is spilled into the second nozzle control space (83) and a relief line (88).
24. Fuel injection device according to Claim 22, characterized in that the guide leakage between the first and the second needle part (31, 32) flows out into the nozzle control space (83) via the longitudinal duct (84) between the sleeve-shaped body (89) and the inner needle part (32).

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