EP1404961A1

EP1404961A1 - Fuel injector having injection curve shaping carried out by switchable throttling elements

Info

Publication number: EP1404961A1
Application number: EP02748597A
Authority: EP
Inventors: Friedrich Boecking
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2001-06-29
Filing date: 2002-06-19
Publication date: 2004-04-07
Anticipated expiration: 2022-06-19
Also published as: JP2004521262A; WO2003004856A1; DE10131640A1; EP1404961B1; DE50206087D1; US20060086818A1

Abstract

The invention relates to a fuel injector for injecting fuel into the combustion chamber of an internal combustion engine. A multi-way valve (18) is accommodated inside the injector body (2) and comprises a valve body (20) enclosed by a valve space (19). A control space (3) is subjected to the action of pressure or relieved from pressure when the multi-way valve (18) inside the injector body (2) is actuated, whereby the control space (3) is pressurized via at least one inlet throttling element (15) and is relieved from pressure via at least one discharge throttling element (16). Another discharge throttling element (25) is connected down from the valve space (19) of the multi-way valve (18) on the discharge side, whereby the valve space (19) and the control space (3) are connected to one another via a main flow channel (8) and an auxiliary flow channel (11).

Description

Fuel injector with injection course shaping through switchable throttle elements

Technical field

Fuel injection systems on direct-injection internal combustion engines are increasingly being implemented as accumulator injection systems. A high-pressure pump or a high-pressure storage space is used to supply the individual fuel injectors in an injection sequence under extremely high pressure, the fuel being supplied at an extremely high pressure level almost without fluctuations in pressure. In addition to supplying fuel at a high, almost constant pressure level, the start of injection and the end of injection are of great importance with regard to particle emission, depending on the progress of the combustion in the combustion chamber of an internal combustion engine.

State of the art

From DE 199 10 589 AI an injection valve for an internal combustion engine is known which comprises a servo valve which hydraulically controls the opening and closing movement of the nozzle needle for the injection process. The injection valve comprises a valve body and a valve element movably arranged therein, which presses on a valve seat in the closed position. Depending on the pressure prevailing in a control room, the connection between an inlet channel and an injection nozzle is interrupted, the pressure in the control room being controlled by an actuator. The valve element has a channel with a throttle, which leads to a groove in the valve element, the groove comprising a piston-shaped shoulder, which lies essentially sealingly against the wall of a bore in the valve body when the servo valve is closed. The bore widens radially at a distance from the upper edge of the groove in relation to the position of the valve element when the servo valve is closed, so that when the servo valve is open there is a direct connection between the valve seat and the groove, from which channels lead to the injection nozzle. This solution can be used in the initial phase of injection Establish throttled connection to the injection nozzle of the injection system. In the further course of the injection process, when the servo valve opens further, bypassing the throttle that is active during the initial phase of the injection, a direct dethrottled connection to the injection nozzle is established, so that an unimpeded injection occurs during the transition from the initial to the main phase of the injection process of fuel can take place in the combustion chamber of the internal combustion engine.

EP 0 994 248 A2 relates to a fuel injector with injection profile shaping by means of a piezoelectric stroke in the injector body. To avoid undesired exhaust gas emissions, at least three different injection rates covering the operating range of an internal combustion engine are desirable. These injection rates can be characterized by a ramp-like rise, a boot phase and an approximately trapezoidal phase. In the solution known from EP 0 994 248 A2, a fuel injector comprises an injector body which contains an injection opening. A nozzle needle is movably arranged within the injector body and movable between an open position and a closed position. In addition, a piezo actuator is arranged in the injector body and can be moved between an activated and an deactivated position. The nozzle needle and the piezo actuator are coupled to one another by means of a coupling element in such a way that the movement of the piezo actuator within the injector body is translated into a larger stroke movement of the nozzle needle. The nozzle needle can be stopped in a plurality of stroke positions between its open position and its closed position, which allows the injection quantity to be influenced in accordance with the holding position of the nozzle needle in the injector body. With this solution, the injection of corresponding injection rates into the combustion chamber and thus a shaping of the injection process can be achieved.

Presentation of the invention

The solution according to the invention offers the advantage of being able to shape the injection course by switching on or off discharge throttle elements or inlet throttle elements in combination with a multi-way valve e.g. to represent a 3/3-way valve in a fuel injector.

In a first general embodiment variant, a first outlet throttle element is always connected downstream of the outlet of the valve chamber of the multi-way valve. According to this variant, in which the valve chamber of the multi-way valve is connected via a main flow channel and a bypass channel to be run parallel to the control valve actuating the nozzle needle. connection, a further outlet throttle element can be accommodated both in the secondary flow channel and in the main flow channel. However, the inlet throttle element can both be arranged to open into the valve chamber of the multi-way valve and also open directly into the control chamber or be designed to open into one of the channels connecting the valve chamber to the control chamber, for example the main flow channel.

The control chamber actuating the nozzle needle is always filled with a control volume by means of the inlet throttle, which can be arranged at various points in the injector body of the fuel injector. If the further outlet throttle element is designed in a smaller throttle cross-section compared to the first outlet throttle element downstream of the valve chamber of the multi-way valve, these two outlet throttle elements can be connected both in series and in parallel to one another for shaping the course of the injection. Particularly good shaping of the injection profile can be achieved with the first outlet throttle element connected in series with the further outlet throttle element.

In addition to the series or parallel connection of outlet throttle elements, it is also possible, according to a further general embodiment variant of the concept on which the invention is based, to form an injection profile on a fuel injector which is equipped with two inlet throttle elements and two outlet throttle elements by means of a suitable circuit combination of the throttle elements. According to this general design variant, too, one of the outlet throttle elements in the valve chamber of the multi-way valve always remains downstream. As already mentioned above, the multi-way valve can be a 3/3-way valve, injection course shaping taking place in particular through the combination of the further outlet throttle element, either incorporated according to a sub-variant in the main flow or another sub-variant in the bypass duct , According to the general design variant outlined, a first inlet throttle element always opens directly into the control chamber, which controls the nozzle needle / tappet movement in the injector body. The further inlet throttle element of this solution variant is arranged such that it is connected to the first outlet throttle element when it is opened as a bypass. The control chamber can thus be filled via two inlet throttle elements which can be connected in parallel, which enables a rapid needle closing speed. The injection course shaping is supported in that two discharge throttle elements can be switched in series or individually acting.

With this general embodiment variant, a particularly quick closing of the nozzle needle in the injector body can be achieved. A fuel injector that is manufactured in accordance with the two general design variants outlined is characterized by particularly inexpensive and simple manufacturability.

drawing

The invention is described in more detail below with reference to the drawing.

It shows:

Figure 1 shows an embodiment variant with a control room downstream

Outlet throttle, a further outlet throttle in the bypass duct and an inlet throttle in the valve chamber,

FIG. 2 shows an embodiment variant with a first outlet throttle element accommodated in the main flow channel and an inlet throttle opening into the control chamber,

FIG. 3 shows an embodiment variant according to FIG. 2 with the inlet throttle opening into the valve chamber,

Figure 4 shows an embodiment variant with an opening in the main flow channel

Inlet throttle,

5 shows a control chamber which is acted upon by control volume via an inlet throttle opening into it and which is followed by an outlet throttle with a further inlet throttle opening into the valve chamber,

FIG. 6 shows an embodiment variant according to FIG. 5 with a further inlet throttle element opening into the bypass duct,

FIG. 7 shows an embodiment variant according to FIG. 5 with a further outlet throttle element incorporated in the main flow channel and a further inlet throttle and above this opening

Figure 8 shows an embodiment variant as shown in Figure 7 in the

Valve chamber of the multi-way valve opening further inlet throttle element. design variants

FIG. 1 shows an embodiment variant with an outlet throttle element connected downstream of a control chamber, a further outlet throttle element in the bypass duct and an inlet throttle opening into the valve chamber of a multi-way valve.

An injector for injecting fuel into the combustion chamber of an internal combustion engine comprises an injector body 2, in which a control chamber 3 is formed. The control room 3 is delimited on the one hand by a control room ceiling 4 of the injector body 2 and on the other hand by an end face 6 of a nozzle needle tappet arrangement 5. Furthermore, the control room 3 is delimited by a control room wall 7 of the injector body 2. The control chamber 3 is connected to a valve chamber 19 of a multi-way valve 18 via a first flow channel, the main flow channel 8 via a control chamber-side opening 9 and a valve chamber-side opening 10. The multi-way valve 18 is preferably designed as a 3/3-way valve. Furthermore, the control chamber 3 is connected to the valve chamber 19 of the multi-way valve via a second flow channel 11, the bypass channel. The mouth of the flow channel 11 on the control room side is identified by reference numeral 12, while the mouth of the secondary flow channel 11 on the valve room side is identified by reference number 13. Both the main flow channel 8 and the secondary flow channel 11 between the control chamber 3 and the valve chamber 19 can be flowed through by fuel in both flow directions 29 and 30.

The valve chamber 19, in which a closing body 20 configured in a spherical configuration in the illustration according to FIG. 1 is accommodated, is connected via a first inlet throttle element 15 to a first inlet 14 on the high-pressure side. An outlet throttle element 16 is arranged in the bypass duct 11 and has a cross-sectional area 17 (A ₂ ).

Above the spherically configured closing body 20 of the multi-way valve 18, a transmission element 21 acting on the closing body 20 is shown, which can be actuated by an actuator (not shown here) - be it a piezo actuator or a solenoid valve. Between the outer surface of the transmission element 21 and the wall of the injector body 2, an annular gap 22 is formed, from which a branch 23 runs in the direction of an outlet 24. In outlet 24, downstream of branch 23, a further outlet throttle element 25 is formed, which is designed in a cross-sectional area Aj. The valve body 20 of the multi-way valve 18 can be switched back and forth by means of the transmission element 21 between a first seat 27 and a further, the second seat 28. In order to achieve an injection course shaping, the first flow restriction is Sel element 16, which is received in the bypass duct 11 in the illustration according to FIG. 1, is provided with a cross-sectional area A, which is dimensioned smaller than the cross-sectional area 26 A _{2 of} the further outlet throttle element.

When the valve body 20 of the multi-way valve 18 is placed in the second valve seat 28, the first outlet throttle element 16 received in the bypass duct 11 acts in the outlet direction 30 of the control volume from the control chamber 3 and the further outlet throttle element 25 acted upon via the valve chamber 19 with the control volume to be controlled in the outlet 24 in series. In the case of discharge throttle elements 16 and 25 connected in series, very good injection curve shaping can be achieved in accordance with the dimensioning of the throttle cross sections A, 17 and A ₂ 26 configured flow areas.

FIG. 2 shows an embodiment variant with a first outlet throttle element received in the main flow channel and an inlet throttle element opening directly into the control chamber.

According to this embodiment variant, the valve chamber 19 of the multi-way valve 18 and the control chamber 3 in the injector body 2 are connected via two flow channels running parallel to one another, ie the main flow channel 8 and the secondary flow channel 11. The valve body 20 of the multi-way valve 18 can be moved by means of a transmission element 21 between a first valve seat 27 and a second valve seat 28 above the main flow channel 8. From the annular gap 22, which actuates the transmission element 21 to control the valve body 20, an outlet 24 branches off at the branch point 23, in which the further outlet throttle element 25 with cross-sectional area A ₂ , reference numeral 26, is integrated. In contrast to the representation according to FIG. 1, the control chamber 3 is supplied with fuel directly by a permanently acting inlet throttle 14 from a first inlet 14 on the high-pressure side. Furthermore, in contrast to the illustration according to FIG. 1, the first outlet throttle element 16 is integrated into the main flow channel 8.

In this embodiment variant, the first outlet throttle element 16, accommodated in the main flow channel 8, and the further outlet throttle element 25, accommodated in the outlet 24, act parallel to one another. According to this embodiment variant, too, the cross-sectional area 17 A of the first outlet throttle element 16 lies below the cross-sectional area 26 A _{2 of} the further outlet throttle element.

FIG. 3 shows an embodiment variant according to FIG. 2, however, with a permanently acting inlet throttle opening into the valve chamber. This embodiment variant differs from that according to FIG. 2 only in that the permanently acting first inlet throttle element 15 of the first high-pressure inlet 14 does not open directly into the control chamber 3 but laterally into the valve chamber 19 surrounding the valve body 20 of the multi-way valve 18 in the injector body 2. The main flow channel 8 is therefore flowed through both in relation to the control chamber 3 in the feed direction 29 and in the drain direction 30 by the control volume. The control chamber-side orifices of the main flow channel 8 and the secondary flow channel 11 are identified with the reference numerals 9 and 12 analogously to the illustration according to FIGS. 2 and 3, while the valve chamber-side orifices 10 and 13 of the main flow channel 8 and the secondary flow channel 11 are also identified in the same way as in the previous figures the reference numerals 10 and 13 are identified.

FIG. 4 shows an embodiment variant with a permanently acting inlet throttle element opening into the main flow channel between the valve chamber and the control chamber.

According to this embodiment variant of the idea on which the invention is based, the first outlet throttle element 16 with its cross-sectional area 17 (A,) is arranged directly behind the mouth 9 on the control room side in the control room ceiling 4. In contrast to the representations according to FIGS. 1 and 2, the permanently acting inlet throttle element 15 is in a second additional inlet position, which is identified by reference number 41. The first outlet throttle element 16 received in the main flow channel 8 is flowed through - in relation to the control chamber 3 - in the inlet direction 29 or in the outlet direction 30, the permanently acting inlet throttle element 15 being seen primarily as a leakage quantity limiter, since the actual inlet throttle function depends on the backward flow flow element 17 is taken over - in the feed direction 29. In this embodiment variant too, a branch 23 is assigned to an annular gap 22 above the valve chamber 19 of the multi-way valve 18, which branches into an outlet 24 in which a further outlet throttle element 25 is integrated. The cross-sectional area 26 A _{2 of} the further outlet throttle element 25 is larger than the cross-sectional area A, 17 of the first outlet throttle element 16, which is accommodated in the main flow channel 8 in this embodiment variant and through which the control volume can flow in both directions 29 and 30.

The embodiment variants shown in FIGS. 1 to 4 have in common that when the valve body 20 of the multi-way valve 18 is in its first seat 27 in the injector body 2, the control chamber 3 is filled by the high pressure present in the inlet 14 on the high-pressure side and the nozzle needle / tappet arrangement 5 is held in its closed position. The control chamber is filled by the first inlet throttle element 15, which is arranged at different points according to the embodiment variants shown here. A very good injection course shaping can be achieved in particular with the embodiment variants according to FIGS. 1 and 4, in which the first outlet throttle elements 16 and the further outlet throttle element 25 are connected in series.

FIG. 5 shows a further general embodiment variant of a fuel injector, with a control chamber which is acted upon by a permanently acting inlet throttle opening into it, an outlet throttle being connected downstream of the valve chamber and a first inlet throttle element 15 opening into the valve chamber.

In FIGS. 5, 6, 7 and 8 described below, a further outlet throttle element 25 with a cross-sectional area 26 A _{2 is} connected downstream of the valve chamber 19 of the multi-way valve 18, which is accommodated in the outlet 24, which branches off from the annular gap 22.

Furthermore, the embodiment variants shown in FIGS. 5, 6, 7 and 8 of the control chamber 3 formed in the injector body 2 of the injector 1 are filled directly via a permanently acting first inlet throttle element 15, which in turn is acted upon by a first inlet 14 on the high-pressure side. Another common feature is that in the embodiment variants described below of the concept on which the invention is based, the control chamber 3 and the valve chamber 19 of the multi-way valve 18 via two flow channels, i.e. the main flow channel 8 and the secondary flow channel 11 are connected to one another. The main flow channel 8 can be closed by the spherical valve body 20 of the multi-way valve 18 in the following embodiment variants when it enters the second valve seat 28 or can be released again when the transmission element 21 is actuated by an actuator (not shown).

According to the embodiment variant according to FIG. 5, a first outlet throttle element 16 is accommodated in the flow channel 11 between the valve chamber 19 of the multi-way valve 18 and the control chamber 3. The bypass duct 11 can be flowed through by the flow volume with respect to the control chamber 3 both in the feed direction 29 and in the drain direction 30. Analogously to the embodiment variants shown in FIGS. 1 to 4, the control-side end of the main flow channel is identified by reference number 9 and its valve-chamber-side opening is identified by reference number 10, while the control-chamber end of the bypass flow channel 11 is identified by reference number 12 and its valve-side end by reference number 13. In the exemplary embodiment shown in FIG. 5, a further inlet throttle element 51 opens, which is connected to a further inlet 50 on the high-pressure side. is in the valve chamber. If, according to this embodiment variant, the valve body 20 of the multi-way valve 18 is placed in its first seat 27, the control chamber is quickly fulfilled via the inlet throttle elements 15 and 51 acting in parallel, in this circuit variant the control chamber via the secondary flow channel 11, the main flow channel 8 and the permanently acting one first inlet throttle element 15 is acted upon. The first outlet throttle element received in the bypass duct 11 is flowed through in the rearward direction when the valve body 20 of the multi-way valve 18 is placed in the first valve seat 27; the nozzle needle / needle arrangement 5 is therefore quickly closed by the control chamber acting on the end face 6 of the nozzle needle / tappet arrangement 3 additionally via a further inlet throttle element 51, which in this case opens into the valve chamber 19 of the multi-way valve 18, is filled and consequently a faster pressure build-up occurs in the control chamber 3. In the embodiment variant according to FIG. 5, the further inlet throttle element 51 acts as a bypass to the first outlet throttle element 16 accommodated in the bypass duct 11, and when the valve body 20 is moved in the first valve seat 27, a parallel connection of two inlet throttle elements 15 and 51 is brought about.

According to this embodiment variant, the ability to shape the injection course is given by the fact that, when the valve body 20 is placed in the second valve seat 28 - correspondingly controlled by the actuator actuating the transmission elements 21 - a pressure relief of the control chamber 3 via the series-connected flow restrictor elements, i.e. the first discharge throttle element 16 received in the bypass duct 11 and the further discharge throttle element 25, which can be connected in series therewith, take place in the outlet 24 arranged downstream of the valve chamber 19. The shape of the injection course can be characterized and set by the design of the throttle cross sections 17 and 26 of the first outlet throttle element 16 in the bypass duct 11 and the further outlet throttle element 25 in outlet 24.

FIG. 6 shows an embodiment variant as shown in FIG. 5 with a further inlet throttle element opening into the bypass duct.

According to this embodiment variant, the control chamber 3 in the injector body 2 is filled via a permanently acting first inlet throttle element 15 directly via a first inlet 14 on the high pressure side. Analogous to the design of the main flow channel 8 and the secondary flow channel 11 according to the embodiment variant in FIG. 5, a first outlet throttle element 16 is accommodated in the bypass channel 11 in the embodiment variant shown in FIG. Downstream of the valve chamber of the multi-way valve is an outlet 24, which is a further outlet throttle element 25, designed in cross section 26 A ₂ includes. In contrast to the embodiment variant according to FIG. 5, the further inlet throttle element 51 of a further inlet 50 on the high-pressure side now does not open in the valve chamber 19, but in the bypass duct 11 at a first distance 54 with respect to the first outlet throttle element 16 arranged in the bypass duct 11. The distance 54 according to the embodiment variant in FIG. 6 it is dimensioned such that in the area of the mouth of the further inlet throttle element 51 and the end of the first outlet throttle element 16 in the bypass duct 11, the flow can again be laminar.

If the valve body 20 is placed in its first seat 27 in the valve chamber 19, the first high-pressure inlet 14 and the further high-pressure inlet 50 and the inlet throttle elements 15 and 51 accommodated therein are connected in parallel, so that, according to this embodiment variant, the control chamber 3 is connected in parallel via two Inlets acted on and thus a quick pressure build-up can be realized, which leads to a quick needle closing. Here, too, the further inlet 50 on the high-pressure side is designed as a bypass to the first outlet throttle element 16, which is arranged downstream of the control chamber 3.

When the valve body 20 of the multi-way valve is placed in the second valve seat 28, the pressure in the control chamber 3 is relieved via the outlet throttle elements 16 connected in series in the bypass duct 11 and the further outlet throttle element 25 in the outlet 24 downstream of the valve chamber 19.

In the embodiment variant according to FIG. 7, a modification of the embodiment variant according to FIG. 5 is shown with a further outlet throttle element incorporated into the main flow and above this further inlet throttle element opening into the main flow channel.

According to this variant, too, the control chamber 3 is always acted upon directly by a permanently acting first inlet throttle element 15 via a first inlet 14 on the high-pressure side. The control chamber 19 is followed by an outlet 24, in which a further outlet throttle element 25 is accommodated, which is designed in a cross section 26 A ₂ . In contrast to the embodiment variant shown in FIG. 5, the first outlet throttle element 16 connected downstream of the control chamber is not received in the bypass duct 11, but rather in the main flow duct 8, which can be opened or closed by the valve body 20 of the multi-way valve 18 in the valve chamber 19.

According to this embodiment variant, in which the further inlet throttle element 51 of the further high-pressure inlet 50 opens into the main flow channel 8 at a second distance 55 above the first outlet throttle element 16, the control valve is filled. chamber 3 in the valve body 20 closing the main flow channel 8 via the parallel inlet throttle elements 15 and 51 and the high pressure side inlets 14 and 50 acting on them. Pressure relief of the control chamber 3 takes place according to the embodiment variant of the injector shown in FIG Valve seat provided valve body 20 via the further outlet throttle element received in the outlet 24. The first outlet throttle element 16 accommodated in the main flow channel 8 is not effective since the main flow channel 8 is closed when the pressure in the control chamber 3 is relieved of pressure, so that the pressure relief of the control chamber 3 takes place via the bypass duct 11, the valve chamber 19 and the further outlet throttle element 25 of the outlet 24.

8 shows a slight modification of the embodiment variant according to FIG. 7. In contrast to the illustration according to FIG. 7, the further inlet 50 on the high-pressure side and the further inlet throttle element 51 integrated therein do not open directly into the main flow channel 8, but rather into the valve chamber 19 of the multi-way valve. Analogously to the illustration according to FIG. 7, the first outlet throttle element 16, designed in a first cross section A, 17, is contained in the main flow channel 8. The valve chamber 19 of the multi-way valve is followed by the outlet 24, which comprises the further outlet throttle element 25, designed in cross section A ₂ . If the valve body 20 of the multi-way valve is placed in its first valve seat 27, the control chamber 3 is pressurized, on the one hand, via the first inlet throttle element 15, which permanently fills it, via the first inlet 14 on the high-pressure side, and via the further inlet throttle element 51, which opens into the valve chamber 19, of another Inlet 50 on the high-pressure side. The control chamber is thus filled via the secondary flow channel 11 and the main flow channel 8, the first outlet throttle element 16, which is incorporated in the main flow channel 8 according to the embodiment variant in FIG. 8, acting as the actual inlet throttle.

If, on the other hand, the valve body 20 of the multi-way valve in the valve chamber 19 is placed at its second seat 28, the main flow channel 8 is closed and the pressure in the control chamber 3 is released via the bypass channel 11 into which the outlet 24 downstream of the valve chamber 19 of the multi-way valve 18 is accommodated.

In the illustrated embodiment variants according to FIGS. 5, 6, 7 and 8, the injection profile shaping ability of the injector 1 is achieved in that according to the embodiment variants of FIGS. 5 and 6, when the pressure in the control chamber 3 is relieved, the first outlet throttle element 16 of the bypass duct 11 and the further outlet throttle element 25 of the outlet 24, which is connected downstream of the control chamber 19, act in series and, according to the design of the throttle cross sections A, 17 and A ₂ 26, injection course shaping can be achieved, while in the embodiment variants shown in FIGS. 7 and 8 the pressure relief of the control chamber 3 when the valve body 20 of the multi-way valve 18 is placed in the second valve seat 28 via the bypass duct 11, the valve chamber 19 into the further outlet throttle element 25 acting individually in these cases in the outlet 24.

According to the design variants in FIGS. 5 to 8, when the valve body 20 of the multi-way valve 18 is placed in the second valve seat 28, the control chamber 3 is filled in parallel via the permanently acting first inlet throttle element 15 and the first inlet 18 on the high pressure side and the further inlet throttle element 51 and the other inlet side Inlet 50, which in the variants 5, 6, 7 and 8 at different points, ie the valve chamber 19, the secondary flow channel 11, main flow channel 8 can open.

Claims

claims

1. Fuel injector for injecting fuel into the combustion chamber of an internal combustion engine, in which a multi-way valve (18) is accommodated, which comprises a valve body (20) accommodated in a valve chamber (19) and, when the multi-way valve (18) is actuated, a one in the injector body (2 ) arranged control chamber (3) can be depressurized or pressurized, the control chamber (3) can be pressurized via at least one inlet throttle element (15) and can be depressurized via at least one outlet throttle element (16), characterized in that the valve chamber (19) of the multi-way valve (18) a further outlet throttle element (25) is connected downstream, the valve chamber (19) and the control chamber (3) being connected to one another via a main flow channel (8) and a secondary flow channel (11).

2. Fuel injector according to claim 1, characterized in that the main flow channel (8) through the valve body (20) of the multi-way valve (18) can be closed on a second valve seat (28).

3. Fuel injector according to claim 1, characterized in that the first outlet throttle element (16) is arranged in the bypass duct (11).

4. Fuel injector according to claim 1, characterized in that the first outlet throttle element (6) is arranged in the main flow channel (8).

5. Fuel injector according to claim 1, characterized in that the first outlet throttle element (16) has a smaller cross-section (17) than the cross-section (26) of the further outlet throttle element (25) connected downstream of the valve chamber (19).

6. Fuel injector according to claim 4, characterized in that the permanently acting first inlet throttle element (15) opens into the main flow channel (8) above the first outlet throttle element (16).

7. Fuel injector according to claim 3, characterized in that the permanently acting first inlet throttle element (15) opens into the valve chamber (19) of the multi-way valve (18).

8. Fuel injector according to claim 4, characterized in that the permanently acting first inlet throttle element (15) opens directly into the control chamber (3).

9. Fuel injector according to claim 7, characterized in that a further inlet throttle element (51) opens directly into the control chamber (3).

10. Fuel injector according to claim 3, characterized in that the permanently acting inlet throttle element (15) opens above the first outlet throttle element (16) and the control chamber (3) can be acted upon via a further inlet throttle element (51).

11. Fuel injector according to claim 10, characterized in that the permanently acting first inlet throttle element (15) opens at a first distance (54) from the first outlet throttle element (16) in the bypass duct (11).

12. The fuel injector according to claims 3 and 6, characterized in that the control chamber (3) can be acted upon via a further inlet throttle element (51).

13. Fuel injector according to claim 6, characterized in that the permanently acting throttle element (15) on the main flow channel (8) at a second distance (5) from the first outlet throttle element (16) is arranged opening.

14. Fuel injector according to claim 4, characterized in that the permanently acting inlet throttle element (15) with the valve chamber (19) of the multi-way valve

(18) and the further inlet throttle element (51) are directly in fluid connection with the control chamber (3).