WO2005019638A1

WO2005019638A1 - Fuel injection valve for internal combustion engines

Info

Publication number: WO2005019638A1
Application number: PCT/DE2004/001306
Authority: WO
Inventors: Peter Boehland; Thomas Kuegler; Predrag Nunic; Detlev Potz
Original assignee: Robert Bosch Gmbh; SANDER-POTZ, Maike; Potz, Wendelin
Priority date: 2003-08-20
Filing date: 2004-06-22
Publication date: 2005-03-03
Also published as: DE10338228A1; EP1658427B1; EP1658427A1; DE502004006203D1

Abstract

The invention relates to a fuel injection valve which comprises a housing (1) with a valve seat (20) configured therein and an interior valve needle (17) and an exterior valve needle (15). The pressure in an exterior control chamber (56) exerts a closing force onto the exterior valve needle (17) and the pressure in an interior control chamber (54) exerts a corresponding closing force onto the interior valve needle (15). The interior control chamber (54) is linked with a control valve chamber (60) of a control valve (30) via an interior outlet throttle (51) and the exterior control chamber (56) via an exterior outlet throttle (49), a valve member (62) being disposed in said control valve chamber (60). The interior control chamber (54) is linked with a high-pressure area (8) via an interior inlet throttle (47) and the exterior control chamber (56) via an exterior inlet throttle (45). The valve member (62) can assume a first, a second and a third switched position so that the pressure in the control chambers (54; 56) can be controlled to open only the exterior valve needle (17) as well as both valve needles (15; 17).

Description

Fuel injection valve for internal combustion engines

State of the art

The invention is based on a fuel injection valve for internal combustion engines, as is known for example from DE 102 22 196 AI. The known fuel injection valve has a housing in which a valve seat is formed, from which a plurality of injection openings originate. Arranged in the housing is an outer valve needle and an inner valve needle slidably mounted in it, which cooperate with the valve seat end on the valve seat and thus control the opening of at least two injection openings. An outer control chamber is formed in the housing, the pressure of which, at least indirectly, can exert a closing force on the end of the outer valve needle remote from the valve seat. In addition, an inner control chamber is formed in the housing, the pressure of which, at least indirectly, can exert a closing force on the end of the inner valve needle facing away from the valve seat. Both closing forces act in the direction of the valve seat and press the valve needles against the valve seat. The inner control chamber is connected to a control valve chamber of a control valve via an inner outlet throttle, and likewise the outer control chamber is connected to this control valve chamber via an outer outlet throttle. The control valve chamber can be connected to a leakage oil chamber via an outlet opening, the various inlets being controlled by a valve member which is arranged in the control valve chamber and which can assume various switching positions.

In the known fuel injection valve, the inner control chamber is formed within a control piston against which the valve outer needle rests. As a result, the pressure in the inner control chamber depends on the stroke of the valve outer needle. As a result, independent control of the outer valve needle and inner valve needle is no longer possible. The pressure drop in the inner control has the effect that a precisely balanced system of inlet throttles and outlet throttles must be available and, moreover, the pressure areas on the valve inner needle must be precisely adapted to the pressure conditions in order to be able to carry out the control. This is technically complex and costly to implement.

Advantages of the invention

The fuel injection valve according to the invention with the characterizing features of patent claim 1 has the advantage over the prior art that independent control of the outer valve needle and the inner valve needle can be achieved, which allows greater freedom in the design of the corresponding component dimensions and moreover enables a more precise metering of the injected fuel quantity , For this purpose, the inner control chamber has an inner inlet throttle and the outer control chamber has an outer inlet throttle, which are connected to a fuel-filled high-pressure region formed in the housing. The control valve chamber can be connected to a leakage oil chamber by the valve member, which can assume a first, a second and a third switching position, in the first switching position the drain opening, which connects the control valve chamber to the leakage oil chamber, is closed by the valve member in which second switching position, both the inner outlet throttle and the outer outlet throttle are connected to the leakage oil chamber via the now opened outlet opening and in the third switching position the outer outlet throttle is connected to the leakage oil chamber and the inner outlet throttle is closed by the valve member. With this design of the control valve, which corresponds in its function to a 3/3-way valve, it is possible to connect only the outer control chamber to the leakage oil chamber, which leads to a pressure relief there and thus causes the valve outer needle to open, o - The, when the valve member is in its second switching position, relieves both the imieren and the outer control chamber, so that both valve needles open.

Advantageous embodiments of the subject matter of the invention are possible through the subclaims. In a first advantageous embodiment, the valve member can be moved via a piezo actuator connected to the valve member. The piezo actuator allows the valve member to go directly to any desired position can be brought between the first and the third switching position. In this case, the valve member is advantageously in its first switching position against a first valve seat and in its third switching position against a second valve seat, the valve member moving linearly between these two switching positions. The second switching position of the valve member is between the first and the third switching position.

In a further advantageous embodiment, the inner control chamber and the outer control chamber are connected to one another when both the valve outer needle and the valve inner needle are in their closed position, i.e. are in contact with the valve seat. This creates a common control chamber for both valve needles, which is connected to the high-pressure area via two inlet throttles. Likewise, this common control chamber is connected to the control valve chamber via two flow restrictors, which now makes it possible, depending on the switching position of the valve member, to relieve the common control chamber via one or both flow restrictors. This leads to a rapid or less rapid pressure drop in the common control room, so that the outer valve needle opens either quickly or somewhat more slowly. It when the outer control chamber is separated from the inner control chamber by the stroke movement of the outer valve needle is particularly advantageous. After reaching this position of the valve needles, the two valve needles can be controlled independently, so that the inner valve needle can be kept closed while the outer valve needle is open.

In a further advantageous embodiment, the end faces of the valve needles facing away from the valve seat do not directly delimit the inner or outer control chamber, but rather the valve needles abut an inner and an outer valve piston, which delimit the respective control rooms. This has the advantage that the control pistons can be manufactured separately, which makes it possible, for example, to use other materials or to use different materials

Manufacturing process.

In a further advantageous embodiment, the outer control space is designed as an annular space, which is always separated from the inner control space. As a result, both control rooms can be controlled separately. The annulus can either the valve inner needle or the inner valve piston surround, so that a compact design of the fuel injector is made possible.

Further advantages and advantageous configurations of the subject matter of the invention can be found in the description and the drawing.

drawing

The drawing shows two exemplary embodiments of the fuel injection valve according to the invention. It shows

1 shows a longitudinal section through a fuel injection valve according to the invention, the middle part being omitted for the sake of clarity, FIGS. 2a to 2c show an enlargement of the control valve in different switching positions,

3 a and 3 b show an enlargement of the section from FIG. 1 designated III in the area of the control rooms and FIG. 4 shows a second exemplary embodiment of the fuel injection valve according to the invention, only the section labeled A of the fuel injection valve shown in FIG. 1 being shown here.

Description of the embodiments

FIG. 1 shows a first exemplary embodiment of the fuel injection valve according to the invention. The fuel injector is shown in a section A and a section B, the part between these two sections being omitted for the sake of clarity. Section B, which represents the actual nozzle, is sufficiently known from the prior art, so that only its essential parts are described here, whereas the section

A contains the essential parts for the invention.

The fuel injection valve comprises a housing 1, which comprises a holding body 9, a throttle plate 7, a control body 5 and a valve body 3, which abut one another in this order. The valve body 3 is replaced by a Clamping nut 2, which rests on a shoulder of the valve body 3 and is screwed into a thread on the holding body 9, is pressed against the control body 5, so that the control body 5 presses on the holding body 9 via the throttle plate 7. As a result, all parts of the housing 1 remain in their intended position. A bore 11 is formed in the valve body 3, which is designed as a blind bore and which forms a conical valve seat 20 at its end on the combustion chamber side. Two rows of injection openings 26, 28 are formed in the conical valve seat 20, the outer row of injection openings 26 being formed upstream of the inner row of injection openings 28. Both rows of injection openings 26, 28 open into the combustion chamber of the same in the installed position of the fuel injection valve.

In the bore 11, an outer valve needle 17 is arranged to be longitudinally displaceable and is sealingly guided on a section in the bore 11 facing away from the combustion chamber. Between the outer valve needle 17 and the wall of the bore 11, a pressure chamber 12 is formed, which also has an inlet channel 8 running in the holding body 9, the throttle valve 7, the control body 5 and the valve body 3

Fuel can be filled under high pressure. The inlet channel 8 opens into a radial extension of the pressure chamber 12, this radial extension directly adjoining the section of the bore 11 in which the valve outer needle 17 is guided. At the end of the outer valve needle 17 facing the valve seat, an outer valve sealing surface 22 is formed which is at least approximately frustoconical and which interacts with the valve seat 20. The outer valve needle 17 has a longitudinal bore 16, so that the outer valve needle 17 forms a hollow needle. In the longitudinal bore 16 of the valve outer needle 17, a valve inner needle 15 is arranged so as to be longitudinally displaceable, which also has a conical valve sealing surface 24 at its end on the valve seat side, with which the valve inner needle 15 interacts with the valve seat 20.

The control of the outer injection openings 26 and of the inner injection openings 28 takes place in such a way that when the pressure in the pressure chamber 12 is sufficiently high, a force is exerted on the pressure shoulder 13 which is directed away from the valve seat. As a result, the outer valve needle 17 moves away from the valve seat 20, so that the outer injection openings 26 are released and fuel is injected from the pressure chamber 12 through the outer injection openings 26 into the combustion chamber. Also lifts the valve inner needle 15, which is directed away from the valve seat 20 due to the hydraulic pressure on parts of the valve sealing surface 24 Experienced force from the valve seat 20, the inner injection openings 28 are released and fuel is injected simultaneously through the outer injection openings 26 and the inner injection openings 28. When the outer valve needle 17 or the outer and the inner valve needle are seated on the valve seat 20, all the injection openings 26, 28 are closed and the injection is ended.

A piston chamber 32 is formed in the control body 5 and is open on both end faces of the control body 5. An outer valve piston 34 and an inner valve piston 36 arranged in the outer valve piston 34 are arranged in the piston chamber 32. Here, the outer valve piston 34 abuts the valve outer needle 17, while the inner valve piston 36 abuts the valve inner needle 15. In addition, a closing spring 38 is arranged in the piston chamber 32, which is supported at one end on a shoulder formed in the piston chamber 32 and at the other end on the outer valve piston 34, the closing spring 38 being pretensioned such that it engages the outer valve piston 34 and thus the outer valve needle 17 presses in the direction of the valve seat 20. FIGS. 3a and 3b each show an enlargement of the piston chamber 32.

The outer valve piston 34 delimits, with its end facing away from the valve outer needle 17, an outer control chamber 56, which is delimited on the outside by the wall of the piston chamber 32 and the outer valve piston 34 opposite by the throttle plate 7. The outer control chamber 56 is connected to the inlet channel 8 via an inlet throttle 47, via a connecting groove 53 formed in the throttle plate 7. In addition, an outlet throttle 49 extends from the outer control chamber 56, which opens into a control valve chamber 60 of a control valve 30, which is arranged in the holding body 9. The inner valve piston 36 delimits, with its end facing away from the valve inner needle 15, an inner control chamber 54, which is connected to the inlet channel 8 via an inlet throttle 47, which is formed in the throttle plate 7, via the connecting groove 53. The inner control chamber 54 is also connected to the control valve chamber 60 via an inner outlet throttle 51.

A leak oil chamber 40 is formed in the holding body 9, which is connected to a fuel return system and in which there is always a low fuel pressure prevails. The piston chamber 32 is connected to the leakage oil chamber 40 via an outlet channel 42, which runs in the holding body 9 of the throttle plate 7 and in the control body 5, so that there is always a low fuel pressure in the piston chamber 32. Fuel emerging from the pressure chamber 12 and flowing between the valve outer needle 17 and the wall of the bore 11 is discharged so that there is no pressure increase in the piston chamber 32. The leakage oil chamber 40 is also connected to the control valve chamber 60 via an outlet opening 68. Figure 2a shows the detailed structure of the control valve 30 and makes the mode of operation clear. A valve member 62, which is connected to a piezo actuator 66, is arranged in the control valve chamber 60. With the aid of the piezo actuator 66, the valve member 62 can be moved in the longitudinal direction in the control valve chamber 60. The valve member 62 has a first sealing surface 74 with which the valve member 62 in the first switching position shown in FIG. 2a bears against a first valve seat 70 formed in the control valve chamber 60. As a result, the drain opening 68, which is designed as an annular gap surrounding the valve member 62 and through which the

Control valve chamber 60 is connected to the leak oil chamber 40, closed. Via a closing spring 64 arranged in the control valve chamber 60, the valve member 62 is pressed into contact with the first valve seat 70, so that the valve member 62 remains in this first switching position when the piezo actuator 66 is not energized. In the first switching position, both flow restrictors 49, 51, which open into the control valve chamber 60, are open. Since the control valve chamber 60 now has no connection to the leakage oil chamber 40, the high fuel pressure that is present in the high-pressure region of the fuel injection valve, that is to say in the inlet channel 8, builds up in the latter. As a result, there is also a high fuel pressure in the outer control chamber 56 and in the inner control chamber 54, which both the outer valve piston 34 and thus the

Valve outer needle 17, as well as the inner valve piston 36 and thus the valve inner needle 15 in the direction of the valve seat 20. In this position of the valve pistons 34, 36, the control spaces 54, 56 are connected to one another and form a common control space. Since the outer valve piston 36 has a larger area delimiting the outer control chamber 56 than the pressure shoulder 13 of the outer valve needle 17, the outer valve needle 17 remains closed, although there is always a high fuel pressure in the pressure chamber 12.

In Figure 2b, the second switching position of the valve member 62 is shown, the latter against the force of the closing spring 64 by movement by means of the piezo actuator 66 can take. In this position, the first sealing surface 74 of the valve member 62 has lifted off the first valve seat 70, so that the drain opening 68 is now open. As a result, fuel flows from the control valve chamber 60 into the leakage oil chamber 40, so that the fuel pressure in the control valve chamber 60 drops. Since both outlet throttles 49, 51 are still open, fuel flows very quickly from the outer control chamber 56 and the inner control chamber 54 via the control valve chamber 60 into the leakage oil chamber 40, the inlet throttles 45, 47 being dimensioned in such a way that less fuel overflows these inlet throttles 45, 47 flow into the control chambers 54, 56 when the outlet throttle 49, 51 flows off. As a result, the pressure in the outer control chamber 54 and in the inner control chamber 56 drops. The third

Switching position of the valve member 62 is shown in FIG. 2 c and shows the valve member 62 as it rests with its end face opposite the first sealing surface 74, which is designed as a second sealing surface 76, on the second valve seat 72, which is designed on the throttle plate 7. In this third switching position, the inner outlet throttle 51 is closed, so that the outer control chamber 56 is now connected to the control valve chamber 60. The drain opening 68 remains open.

The fuel injector works as follows: at the beginning of the injection process, the valve member 62 of the control valve 30 is in its first

Switching position, i.e. in contact with the first valve seat 70. Via the connection of the outer control chamber 56 and the inner control chamber 54 via the outer inlet throttle 45 and the inner inlet throttle 47 to the high-pressure region, that is to say the inlet duct 8, the same fuel pressure as in the inlet duct prevails in both control chambers 54, 56 8. By the hydraulic force on the inner valve piston

36 and the outer valve piston 34, the outer valve needle 17 and the inner valve needle 15 are pressed against the valve seat 20 and close all the injection openings 26, 28. If injection is to take place only through the outer injection openings 26, the valve member 62 is supplied with current through the piezo actuator 66 from its first switching position to the third

Switching position moves, as shown in Figure 2c. The outer outlet throttle 49 is dimensioned in such a way that the pressure in the two control spaces 54, 56 also drops when the inner outlet throttle 51 is closed by the valve member 62. So less fuel flows into the control chambers 54, 56 via the inlet throttles 45, 47 than via the outer outlet throttle 49 into the Leakage oil chamber 40 flows out. As a result, the pressure in the outer control chamber 56 and in the inner control chamber 54 drops until the hydraulic force on the pressure shoulder 13 of the outer valve needle 17 is greater than the hydraulic force and the spring force of the closing spring 38 on the outer valve piston 34. This moves the valve outer needle 17 away from the valve seat 20 and opens the outer

Injection openings 26 through which fuel is now injected into the combustion chamber. The movement of the valve outer needle 17 also moves the outer valve piston 34 until it comes into contact with the throttle disk 7. Due to the beveling of the end face of the outer valve piston 34, a sealing edge 37 is formed on the latter, which, due to its abutment on the throttle disk 7, the outer

Control room 56 separates from the inner control room 54. Since the inner control chamber 54 now has no hydraulic connection to the control valve chamber 60 and thus to the leakage oil chamber 40, the pressure in the inner control chamber 54 does not drop further, but rises again to the level of the inlet channel 8 via a corresponding fuel supply through the inner inlet throttle 47 on. As a result, the hydraulic force on the inner valve piston 36 and thus on the valve inner needle 15 remains so great that the valve inner needle 15 remains in its closed position and closes the inner injection openings 28. To end the injection process, the valve member 62 of the control valve 30 is moved back into the first switching position by the piezo actuator 66, as shown in FIG. 2a. The pressure in the outer control chamber 56 quickly rises again as fuel flows in through the outer inlet throttle 45, since no more fuel flows out through the outer outlet throttle 49. As soon as the fuel pressure in the outer control chamber 56 has risen so far that the force exerted thereby is greater than the hydraulic force on the pressure shoulder 13 of the outer valve needle 17, the outer valve needle 17, driven by the outer valve piston 34, moves back into its closed position, i.e. in contact with the valve seat 20 and thereby closes the outer injection openings 26.

Since the pressure in the combined control chamber 54, 56 drops at the beginning of the injection only via the outlet through the outer outlet throttle 49, this pressure drop is relatively slow, so that the valve outer needle 17 also opens only slowly, which enables precise metering of the injection quantity. Since an injection only through a part of the injection openings usually a pre- or post-injection is only a very small amount of fuel, an exact dosage is particularly important here.

If a large amount of fuel is required in the combustion chamber at full load of the brake engine, the injection should take place through all injection openings 26, 28. For this purpose, the control valve 30 is actuated such that the valve member 62 moves into its second switching position, as shown in FIG. 2b. As a result, the common control chamber, which is formed by the outer control chamber 56 and the inner control chamber 54, is connected to the control valve chamber 60 via the outer outlet throttle 49 and the inner outlet throttle 51. Since a significantly higher discharge cross-section is now available, the pressure in the control spaces 54, 56 drops very rapidly and the valve outer needle 17 first opens in the manner described above and, depending on the design of the pressure surface on the inner valve sealing surface 24 of the valve inner needle 15, with a short or somewhat longer distance also the valve inner needle 15. The inner valve piston moves here

36 until it comes to rest on the throttle disc 7. To end the injection, the valve member 62 of the control valve 30 is moved back to its first switching position, as shown in FIG. 2a. Due to the now closed drain opening 68, there is no connection to the leakage oil chamber 40, which allows the pressure in the inner control chamber 54 and the outer control chamber 56 to rise again rapidly via fuel inflow through the inner inlet throttle 47 and the outer inlet throttle 45, so that the corresponding hydraulic ones Forces on the outer valve piston 34 and the inner valve piston 36 drive both valve needles 15, 17 back into their closed position.

In addition to these two functional examples, other switching options of the control valve 30 are also conceivable. Injection can thus also take place in such a way that valve member 62 first moves into the third switching position, so that, as described above, valve outer needle 17 opens. The valve member 62 can then be moved into the second switching position, in which the inner control chamber 54 is also relieved via the inner outlet throttle 51. As a result, the valve inner needle 15 now also opens, so that the injection takes place first only through the outer injection openings 26 and then through all the injection openings 26, 28, so that an injection profile is formed, the exact profile of which is also via the switching speed of the piezo actuator 66 can be influenced. The valve member 62 is then moved back into its first switching position, so that the valve needles 15, 17 close again in the manner described above.

FIG. 4 shows a second exemplary embodiment of the fuel injection valve according to the invention, only the section of the fuel injection valve designated by A in FIG. 1 being drawn again. Section B of FIG. 1 is identical to the end of the fuel injection valve on the combustion chamber side, as shown in FIG. The fuel injection valve shown in FIG. 4 also has a housing 1, a separate control body 5 being dispensed with and the holding body 9 directly adjoining the throttle disk 7 and this in turn bordering the valve body 3. The valve body 3 is pressed by a clamping nut 2 in the same manner as in the exemplary embodiment shown in FIG. 1 via the throttle disk 7 against the holding body 9. A bore 11 is formed in the valve body 3, in which a valve outer needle 17 and a

Valve inner needle 15 are arranged, which are longitudinally displaceable in the bore 11. At the end facing away from the valve seat, the bore 11 is expanded to a spring chamber 14, in which the closing spring 38 is arranged. The valve outer needle 17 is surrounded by a sleeve 18 which is arranged in the spring chamber 14 and between which and a support ring 19 the closing spring 38 is arranged under prestress. The sleeve 18 abuts the throttle disc 7, so that a closing force is exerted on the valve outer needle 17 via the closing spring 38 and the support ring 19. The inlet channel 8 opens into the spring chamber 14, so that the function of the spring chamber 14 corresponds to the pressure chamber 12 of the exemplary embodiment shown in FIG. The pressure chamber 12 continues as an annular space between the outer valve needle 17 and the wall of the bore 11 up to the valve seat 20.

A bore 39 is formed in the throttle disk 7, into which the valve inner needle 15 projects and in which it is guided. The valve inner needle 15 is longer than the valve outer needle 17, and it has a first annular groove

77, which is formed at the level of the sleeve 18, and a second annular groove 78, which is arranged within the throttle disk 7. The first annular groove 77 and the second annular groove 78 are connected to one another via a connecting groove 79 on the outside of the valve inner needle 15, and the second annular groove 78 is also connected via an outlet channel 58 running in the throttle valve 7 and the holding body 9 connected to the leakage oil chamber 40, so that there is always a low fuel pressure both in the first annular groove 77 and in the second annular groove 78.

The outer control chamber 56, which is connected to the control valve chamber 60 of the control valve 30 via the outer outlet throttle 49, is delimited by the end of the valve outer needle 17 facing away from the valve seat, the sleeve 18, the throttle disk 7 and the valve inner needle 15. The control valve 30 corresponds here in its function and structure to the control valve 30, which is shown in FIG. 1 or FIGS. 2a to 2c. The inner control chamber 54, which is connected to the control valve chamber 60 via the inner outlet throttle 51, is delimited by the end of the valve inner needle 15 facing away from the valve seat and the bottom of the bore 39. The inner control chamber 54 is connected to the outer inlet throttle 49, which in turn opens into the high-pressure region, that is to say into the inlet channel 8. The control valve chamber 60 can be connected to the leakage oil chamber 40 via the drain opening 68 in the same manner as shown in FIGS. 2a to 2c.

The design of the fuel injection valve means that the outer control chamber 56 is always separated from the inner control chamber 54. The operation of the control rooms 54, 56 and their control by the control valve 30 are, however, the same as in the exemplary embodiment shown in FIG. 1. If an injection is to take place only through the outer injection openings 26, the valve member 62 is also moved here from the first to the third switching position, as shown in FIG. 2c. As a result, the valve member 62 comes into contact with its second sealing surface 76 on the second valve seat 72, which is formed here in the throttle disk 7. The inner outlet throttle 51 is thus closed and the connection of the control valve chamber 60 to the leakage oil chamber 40 is opened via the outlet opening 68. The pressure in the outer control chamber 56 drops and the valve outer needle 17 opens in the known manner already described above. The pressure shoulder 13, which is not shown in FIG. 4, is formed closer to the valve seat than in the embodiment shown in FIG. 1. As long as that

The valve member 62 remains in the third switching position, the high pressure remains in the inner control chamber 54, and a fuel flow through the annular gap between the wall of the bore 39 and the inner valve needle 15 is prevented by the second annular groove 78, which is always depressurized via the outlet channel 58, prevented by diverting any fuel that might penetrate. To end the Injection, the valve member 62 is in turn quickly moved back into the first switching position.

For injection via all injection openings 26, 28, the valve member 62 is moved into the second switching position, as shown in FIG. 2b. As a result, both the inner discharge throttle 51 and the outer discharge throttle 49 are turned on in the same way as already described above, as a result of which the pressure drops both in the inner control chamber 54 and in the outer control chamber 56. As a result, the valve outer needle 17 and the valve inner needle 15 open in quick succession and open all the injection openings 26, 28.

By moving the valve member 62 back into the first switching position, the control spaces 54, 56 fill again with fuel under high pressure, so that the outer valve needle 17 and the inner valve needle 15 slide back into their closed position.

In the exemplary embodiment shown in FIG. 4, the pressure drop in the outer control chamber 56 cannot be varied, so that the pressure there drops at the same rate with each opening movement. As a result, the outer valve needle 17 always opens at approximately the same opening speed.

In addition to a piezo actuator 66, the valve member 62 can also be moved by another drive which allows the valve member 62 to be moved in the linear direction and to be moved into the first, second and third switching positions. Piezo actuators are very suitable for this, however, because they work very quickly and can start any length change between their maximum deflections.

Claims

Expectations

1. Fuel injection valve for internal combustion engines with a housing in which a valve seat (20) is formed and a valve outer needle (17) and a valve inner needle (15) are arranged, and with an outer control chamber (56), by means of its pressure at least indirectly, a closing force the outer valve needle (17) can be exercised, and with an inner control chamber (54), the pressure of which can at least indirectly exert a closing force on the inner valve needle (15), the closing forces acting in the direction of the valve seat (20) and the inner control chamber (54) are connected to a control valve chamber (60) of a control valve (30) via an inner discharge throttle (51) and the outer control chamber (56) via an outer discharge throttle (49), the control valve chamber (60) via a discharge opening (68) can be connected to a leakage oil chamber (40) and a valve member (62) is arranged in the control valve chamber (60), characterized in that the inner control chamber (54) via e an inner inlet throttle (47) and the outer control chamber (56) are connected to a high-pressure region (8) via an outer inlet throttle (45), and that the valve member (62) in the control valve chamber (60) has a first, a second and a third switching position so that in the first switching position the drain opening (68) is closed, in the second switching position both the inner drain throttle (51) and the outer drain throttle (49) via the open drain opening (68) with the leakage oil chamber (40) are connected and in the third switching position the outer outlet throttle (49) is connected to the leakage oil chamber (40) and the inner outlet throttle (51) is closed by the valve member (62).

2. Fuel injection valve according to claim 1, characterized in that there is always a low pressure in the leak oil chamber (40).

3. Fuel injection valve according to claim 1 or 2, characterized in that the valve member (62) via a piezo actuator (66) is movable.

4. Fuel injection valve according to claim 1, characterized in that the valve member (62) bears in its first switching position on a first valve seat (70) and in its third switching position on a second valve seat (72), the valve member (62) between the first and the third switching position moves linearly and is in its second switching position between the two valve seats (70; 72).

5. Fuel injection valve according to claim 1, characterized in that the inner control chamber (54) and the outer control chamber (56) are connected to each other when both the valve outer needle (17) and the valve inner needle (15) in their closed position in contact with the valve seat (20).

6. Fuel injection valve according to claim 5, characterized in that the outer control chamber (56) is separated from the inner control chamber (54) by the stroke movement of the valve outer needle (17).

7. Fuel injection valve according to claim 5 or 6, characterized in that the valve outer needle (17) abuts with its end remote from the valve seat on a movable, outer valve piston (34) which delimits the outer control chamber (56).

8. Fuel injection valve according to claim 7, characterized in that a sealing edge (37) is formed on the outer valve piston (34), which sealing edge (37) comes into contact with a sealing surface during the opening stroke movement of the outer valve needle (17) and thus the outer control chamber ( 56) from the inner control room (54).

9. Fuel injection valve according to claim 1, characterized in that the outer control chamber (56) is designed as an annular space which is always separated from the inner control chamber (54).

10. Fuel injection valve according to claim 9, characterized in that the inner control chamber (54) through a bore (39) in the housing (1) and the end face of an inner valve piston (36) is limited, the inner valve piston (36) facing away from the valve seat Face of the valve inner needle (15) abuts.

11. Fuel injection valve according to claim 10, characterized in that the outer control chamber (56) surrounds the inner valve piston (36) and is delimited by an outer valve piston (34) which bears on the valve outer needle (17).

12. Fuel injection valve according to claim 7 or 11, characterized in that the outer valve piston (34) and the valve outer needle (17) are made in one piece.

13. Fuel injection valve according to claim 10, characterized in that the inner valve piston (36) and the valve inner needle (15) are made in one piece.

14. Fuel injection valve according to one of claims 1 to 13, characterized in that the outer control chamber (56), the inner control chamber (54) and the control valve chamber (60) are filled with fuel.