WO2004099603A1

WO2004099603A1 - Fuel injection valve free of loss

Info

Publication number: WO2004099603A1
Application number: PCT/CH2004/000266
Authority: WO
Inventors: Marco Ganser
Original assignee: Ganser-Hydromag Ag
Priority date: 2003-05-08
Filing date: 2004-05-03
Publication date: 2004-11-18
Also published as: ATE445098T1; DE502004010199D1; EP1620645A1; EP1620645B1

Abstract

The invention relates to a fuel injection valve for intermittently injecting fuel into the combustion chamber of an internal combustion engine. Said valve comprises a membrane (46) which separates the control chamber (48), and thus the high-pressure chamber (24), from the actuator arrangement (44) in a tight manner, thus ensuring that there is no loss of fuel under very high pressure. The movement of the membrane (46) by means of the actuator arrangement (44) enables the needle-type injection valve member (22) to be lifted from the injection valve seat (20) for an injection process and moved towards the same in order to end the injection process.

Description

Warlustfireies fuel inspection file

The present invention relates to a fuel injection valve for intermittent fuel injection into the combustion chamber of an internal combustion engine according to the preamble of claim 1.

In fuel injection valves, as disclosed for example in EP-A-0 603 616, EP-A-0 824 190 and US-A-5,458,293, a needle-shaped injection valve member is arranged in a high-pressure chamber, which is connected to a high-pressure fuel inlet and which cooperates with its one end with an injection valve seat. If the injection valve member is lifted from the injection valve seat, fuel under very high pressure is injected into a combustion chamber of an internal combustion engine from the high pressure chamber. At its other end, the injection valve member delimits a control chamber, which is connected to the high-pressure fuel inlet and thus to the high-pressure chamber via a connection having a throttle passage. The high-pressure chamber can be connected to and separated from a low-pressure chamber on the side opposite the injection valve member by means of an electromagnetically operated pilot valve. The injection valve member is guided in a narrow sliding fit in two regions spaced apart from one another in the axial direction. Between these areas, the injection valve member passes through an annular space which is connected to the low-pressure space. The tight sliding fit serves to seal the Control room and the other of the sealing of the high pressure room. Despite the tight sliding fits, fuel flows into the annulus, causing leakage losses. In addition, fuel flows through the pilot valve from the control chamber into the low-pressure chamber during each injection process, which also causes losses.

The above-mentioned leakage losses are avoided with a fuel injection valve, as is known from EP-A-1 118 765 and US-A-6, 499, 699. However, even with such fuel injection valves, the fuel losses flowing out of a control chamber into a low-pressure chamber during injection processes must be accepted. The control chamber is delimited on the circumference by a sleeve which is arranged in the high-pressure chamber and on which the needle-shaped injection valve member is guided in a narrow sliding fit. Due to this tight sliding fit, however, fuel can at best not flow from the high-pressure chamber into the control chamber into the low-pressure chamber. The high-pressure chamber can in turn be connected to or separated from a low-pressure chamber by means of the pilot valve for controlling the lifting movement of the injection valve member.

A fuel injector, which has the features in the preamble of claim 1, is known from EP-A-0 937 891. The actuator arrangement has a piezoelectric actuator which interacts with a piston element which delimits the control chamber with its side facing away from the actuator. The leakage fuel flowing out of the control chamber along the piston element is led away through a low-pressure discharge line. Starting from this prior art, it is an object of the present invention to provide a generic fuel injector which no longer has any fuel loss.

It is also an object of the present invention to provide a fuel injector of particularly simple construction, which can be manufactured precisely and inexpensively in large numbers.

These objects are achieved with a fuel injector, which has the features of claim 1.

In the case of a fuel injection valve according to the invention, an actuator controlling the movement of an injection valve member is tightly separated from the spaces of the fuel injection valve by means of a sealing element. The injection valve member is controlled by the deflection of the sealing element, for example a membrane, by means of the actuator arrangement. A fuel injection valve according to the invention requires neither a low-pressure chamber nor a line for returning fuel to a fuel storage tank. No fuel can escape from the fuel injection valve, except during an injection process through the injection openings into the combustion chamber. Since fuel injection valves according to the invention operate without a pilot valve, there are also no signs of wear, caused, for example, by cavitation when the fuel is released. Furthermore, the fuel injector according to the invention opens up a new application area in addition to the diesel area. It is also suitable for Injection of gasoline (or other fuels with low viscosity), which is brought to the injection valve, for example, by means of common rail technology, at a very high pressure up to approx. 1000 bar or more. As a result, extremely good atomization is achieved during injection, which cannot be satisfactorily achieved by known direct gasoline injection systems at conventional pressures of 80 to 120 bar. When unloaded, gasoline tends to form vapor bubbles, which is prevented with a fuel injection valve according to the invention without a pilot valve, since no gasoline flows out into a low-pressure chamber.

Preferred embodiments of the fuel injector according to the invention are specified in the dependent claims.

The invention is described in more detail with reference to the embodiments shown in the drawing. It shows purely schematically:

1 shows in longitudinal section a first embodiment of an injection valve according to the invention;

2 shows in longitudinal section a second embodiment of an injection valve according to the invention with a spring which supports the closing movement of the injection valve member;

Fig. 3 in longitudinal section a third embodiment of an inventive

Fuel injection valve, in which the injection valve member is arranged in a unaxed manner with respect to a longitudinal axis of an actuator arrangement; Fig. 4 in longitudinal section part of a fourth

Form of training of an inventive

Fuel injector with a cup-shaped membrane;

5 shows in longitudinal section part of a fifth embodiment of a fuel injector according to the invention, in which a needle guide is arranged on a valve seat element;

6 shows in longitudinal section part of a sixth embodiment of a fuel injector according to the invention;

Fig. 7 also in longitudinal section a part of a seventh embodiment of a fuel injector according to the invention but without one

Control space; and

Fig. 8 in longitudinal section a part of an eighth embodiment of a fuel injector according to the invention.

The fuel injector shown in FIG. 1 has a housing 10, through which a recess 14 extends along a housing axis 12. The recess 14 is essentially rotationally symmetrical and tapered or widening in a step-like manner with respect to the housing axis 12.

A tubular valve seat element 16 with an end region is inserted in a first section of the recess 14; there is an injection nozzle 18 on the valve seat element 16 at the opposite free end educated. On the inside, the injection nozzle 18 has an injection valve seat 20 in the form of the shell of a truncated cone. A needle-shaped injection valve member 22 cooperates with this injection valve seat 20, the end region on this side of which is correspondingly conical in order to rest sealingly on the injection valve seat 20 in the closed position.

The injection valve seat 20 delimits a high-pressure chamber 24, which is connected to a high-pressure fuel inlet 28 - high-pressure fuel connection by means of a fuel supply channel 26 formed in the housing 10. The high-pressure fuel inlet 28 is connected in a known manner to a common rail injection system which supplies fuel to the fuel injection valve at a pressure of up to 1000 bar or higher (in diesel application also above 2000 bar).

The valve seat element 16 is held in the housing 10 by means of a press fit, for example, and it has nozzle openings 30 downstream of the injection valve seat 20 in order to inject fuel under very high pressure into the combustion chamber of an internal combustion engine when the injection valve is open. The injection valve member 22 has guide ribs 32 projecting in the radial direction, by means of which it is guided on the valve seat element 16 so as to be displaceable in the axial direction.

The needle-shaped injection valve member 22 penetrating the high-pressure chamber is guided with its end region 34 facing away from the injection valve seat 20 in a needle guide 36 in a sliding fit. The needle guide 36 is formed on a needle guide element 38, which is inserted into the housing 10 from the side facing away from the valve seat element 16 and is sealingly supported on the shoulder 40 by means of a radially projecting circumferential flange. The flange, which is pressed onto the shoulder 40 by means of an eyebolt 42, seals the high-pressure chamber 24, so that no fuel can flow out of the high-pressure chamber 24 between the housing 10 and the needle guide element 38 into a section of the housing 10 that receives an actuator arrangement 44. On the side of the needle guide element 38 facing the eyebolt 42, there is a sealing element 45 in the form of a membrane 46 which spans the hollow rotationally symmetrical needle guide element 38 and is preferably made of metal, in particular steel. The membrane 46 seals the actuator arrangement 44 with respect to a control chamber 48 which is delimited on the circumferential side by the needle guide element 38 and on the side opposite the membrane 46 by an end face 50 of the injection valve member 22.

The control chamber 48 is connected to the high-pressure chamber 24 by the needle guide 36. However, the flow cross-section between the needle guide element 38 and the injection valve member 22 has such a throttling effect that when the diaphragm 46 is deflected by means of the actuator arrangement 44, significantly more volume is displaced than fuel can flow into the control chamber from the high-pressure chamber 24 or measure out the other way around , For this purpose, the sliding fit in the needle guide 36 has, for example, a play of a few micrometers.

The exposed end face of the sleeve-like needle guide element 38 forms a counter stop 52, which is in shape with one on the injection valve member 22 a circumferential bead trained stop 54 cooperates. The stop 54 and counter stop 52 define the maximum open position of the

Injection valve member 22. The maximum stroke of the injection valve member 22 is indicated by H.

An annular disk 56 is inserted between the eyebolt 42 and the membrane 46. The annular disk 56 and the eyebolt 42 are penetrated at a distance by an actuator shaft 58, which rests with its convexly shaped end face 60 on the correspondingly concave exposed area of the membrane 46. The stress on the membrane 46 can be minimized by this shaping. The membrane 46 is held clamped between the needle guide element 38 and the ring disk 56 with its outer, ring-shaped, hand region which forms a flange.

The actuator shaft 58 is moved back and forth in the axial direction by means of an actuator, which is preferably an electrically controlled piezoelectric or magnetostrictive actuator 62. The electrical connection conductors for the actuator 62 are denoted by 64.

With such actuators 62, strokes of the actuator shaft 58 in the order of magnitude of 0.05 to 0.08 mm can be achieved. In order to nevertheless achieve a stroke H of the injection valve member 22 of approximately 0.2 to 0.3 mm, the diameter of the actuator shaft 58 or of the region of the membrane 46 which can be deflected by means of this is selected to be larger than the diameter of the injection valve member acting as a piston in the needle guide element 38 22nd

The actuator 62 is in an actuator housing 66 recorded, which rests with its housing side facing the membrane 46 against a further shoulder 40 'of the housing 10 and is held in contact with the further shoulder 40' by means of a further eye bolt 42 'which is wound into the housing. The shoulders 40, 40 'and the corresponding tolerance-precise embodiment of the flange of the needle guide element 38 on the one hand and on the other hand of the actuator housing 66, the actuator 62 and the actuator shaft 58, achieve the desired precise interaction of the actuator arrangement 44 with the membrane 46 and thus the injection valve member 22. Tolerance-related, small position differences of the end face 60 of the assembled actuator arrangement 44 and the position of the shoulder 40 'from fuel injector to fuel injector with respect to the position of the diaphragm 46 can be easily compensated for by choosing the thickness of the flange of the needle guide element 38. There are several possibilities based on the same principle of length compensation for exact adherence to the needle stroke H. In series production, it is thus possible to assemble fuel injection valves according to the invention with precisely predefined properties.

For the sake of completeness, it should be mentioned that a bore in the housing 10 is closed by means of an Allen screw 68, which bore was made for drilling the angular fuel supply channel 26.

The fuel injector shown in Fig. 1 functions as follows. In the closed position of the injection valve member 22, as shown in FIG. 1, the actuator 62 is controlled in such a way that the actuator shaft 58 is in its end position in which the diaphragm 46 is maximal in the direction of the control chamber 48 is deflected. The pressure between the high pressure chamber 24 and the control chamber 48 is balanced. Since the sum of the areas of the injection valve member 22 pressurized by the fuel in the direction of the injection valve seat 20 is greater than the sum of the areas pressurized by fuel pressure in the opposite direction, the injection valve member 22 is held in contact with the injection valve seat 20.

To trigger an injection process, the actuator 62 is activated in such a way that the actuator shaft 58 is withdrawn. Since the side of the diaphragm 46 facing the actuator is exposed to ambient pressure, but the side facing the control chamber 48 and thus the high-pressure chamber 24 is exposed to the very high pressure of the fuel, the diaphragm 46 moves with the actuator stem 58 in the direction away from the injection valve seat 20. Since no or very little fuel can be replenished into the control chamber 48 via the needle guide 36 in this short time of movement, the volume of the control chamber 48 is slightly increased and displaced by this movement of the membrane 46, which leads to the lifting of the injection valve member 22 from the injection valve seat 20 leads towards the inside. In other words, the pressure in the control chamber 48 is reduced by the movement of the membrane 46, but this is immediately almost completely compensated for by the movement of the injection valve member 22. At maximum stroke H, stop 54 abuts counter stop 52. The injection process is terminated in a corresponding manner in that the actuator 62 is actuated in such a way that the actuator shaft 58 moves in the direction of the valve seat element 16, so that the injection valve member 22 lies sealingly against the injection valve seat 22. The fuel injector is now for the next one Injection process ready.

The fuel injection valve is therefore also particularly suitable for pre-injections or multiple injections, and also for shaping the injection course by specifically selecting the movement course of the actuator 62 and consequently the injection valve member 22 both when opening and, if appropriate, when closing.

Since the actuator arrangement 44 is completely sealed off from the spaces of the fuel injection valve filled with fuel and the control of the injection valve member 22 takes place without a pilot valve, no fuel losses occur. The fact that the space 63 is not hydraulically connected or connectable to the high pressure space 24 and also not to the control space 48 does not mean that this space is empty (i.e. is under vacuum) or is exclusively filled with air. It may be advantageous to fill this space partially or entirely with a hydraulic fluid, e.g. with hydraulic oil to ensure lubrication and durability of the actuator assembly 44.

The embodiment of the fuel injector according to the invention shown in FIG. 2 is very similar to that according to FIG. 1. In the description of all embodiments, the same reference numerals are used for the same or equivalent parts as in FIG. 1, and only the differences are set out below.

The actuator shaft 58 passes through the actuator 62 and is connected to it on the side 62 'facing away from the membrane 46. This is the direction of movement of the

Actuator shaft 58 compared to that in the Embodiment according to FIG. 1 reversed with the same activation of the actuator 62.

Positioning pins 70 further penetrate the washer 56, the membrane 46 forming the sealing element 45 and the flange of the needle guide element 38. Since these positioning pins 70 engage in corresponding positioning holes 72 in the housing 10, the position of the parts mentioned with respect to the housing 10 is in the radial direction as well set in the rotational position.

Furthermore, the bulge of the injection valve member 22 forming the stop 54 is surrounded with play by a support sleeve 74, which is supported on the one hand at the free end of the needle guide element 38 and on the other hand on a compression spring 76, which in turn is supported on the injection valve member 22 by means of a support disk 78.

The compression spring 76 holds the injection valve member 22 in contact with the injection valve seat 20 when the high-pressure chamber 24 is not under high pressure or the actuator 62 should fail. Otherwise, the mode of operation of the fuel injector shown in FIG. 2 corresponds to that of the embodiment shown in FIG. 1, but the actuator 62 is to be actuated accordingly in reverse.

The embodiment according to FIG. 3 is very similar to that according to FIG. 1, but the longitudinal axes 80, 82 of the actuator arrangement 44 and of the injection valve member 22 are decaxed relative to each other but parallel. Compared to the embodiment according to FIG. 1, this embodiment permits a more compact design of the housing 10. In a slightly modified embodiment, not shown, the axis 80 could also be at an (acute) angle to the longitudinal axis 82.

In order to be able to take up the said relaxation, the needle guide element 38 is no longer designed to be purely rotationally symmetrical. The portion forming the needle guide 36 is rotationally symmetrical with respect to the longitudinal axis 82, whereas the part adjacent to the membrane 46 forming the sealing element 45 is at least approximately rotationally symmetrical with respect to the longitudinal axis 80.

Furthermore, there is no eyebolt 42 in this embodiment; the actuator housing 66 lies directly on the ring disk 56. The actuator housing 66 is pressed against the ring disk 56 and thus the membrane 46 by means of the further eyebolt 42 ′. There is play between the further shoulder 40 'and the counter shoulder on the actuator housing 66. By selecting the thickness of the annular disk 56, tolerance-related, small position differences of the end face 60 from fuel injector to fuel injector can be compensated for in a simple manner.

4 shows a section of a further embodiment of a fuel injector according to the invention. In this embodiment, the valve seat element 16 is placed on the face of the housing 10 and fastened to it by means of a union nut 84. The membrane 46 forming the sealing element 45 and the flange of the needle guide element 38 are clamped between the housing 10 and the injection valve member 22. The fuel supply channel 26 runs from the housing 10 through these two parts to the valve seat element 16 on the circumferential side and by high-pressure space 24 delimited on this injection valve seat 20. The high-pressure space 24 is thus arranged exclusively in the valve seat element 16, with the exception of the high-pressure fuel inlet (not shown) and the fuel supply channel 26.

The membrane 46 is pot-shaped and only part of the actuator shaft 58 of the actuator arrangement 44 is shown, which engages in the membrane 46 and is flat on the end face 60 corresponding to the membrane 46 and is formed along the edge with a suitable radius.

The membrane 46, the needle guide element 38 and the end region of the needle-shaped injection valve member 22 on this side in turn delimit the control chamber 48.

Dashed lines on the needle guide element 38 each show a rib-like, radially outwardly projecting guide element of two guides 38a and 38b, only one of which is necessary in each case in order to center and align the needle guide element 38 in the valve seat element 16 with respect to the housing axis 12. The injection valve member 22 is guided in the needle guide element 38 via the needle guide 36, and in the valve seat element 16 via the guide ribs 32. This means that parts 16, 38 and 22 are exactly aligned with one another and the proper functioning of the fuel injector is ensured. The guides 38a, 38b preferably have three guide elements distributed uniformly in the circumferential direction. 4 clearly shows the preferred area difference between the effective areas of the diaphragm 46 and the injection valve member 22, in order thereby to achieve a translation between the stroke of the actuator shaft 58 and that of the injection valve member 22. In the exemplary embodiment shown, the diameter D1 of the actuator shaft 58 is, for example, 5 mm. The cup-shaped part of the membrane 46 abuts the actuator shaft 58 and is thin-walled, so that the effective area of the membrane 46 corresponds approximately to a diameter of 5.5 to 6 mm. If the diameter D2 of the needle guide 36 or of the injection valve member 22 is chosen between 2.5 and 3 mm for the needle guide 36, a transmission ratio of approximately 4 results. For the sake of completeness, it should be mentioned that the outside diameter D3 of the part interacting with the injection valve seat 20 of the injection valve member 22 is selected at approximately 2 mm.

If the needle guide 36 is designed as a narrow sliding fit for the end region 34 of the injection valve member 22 - with a play of approximately 2 to 4 micrometers - a throttle passage 86 can also be formed in a variant on the needle guide element 38. It is also conceivable, seen in the radial direction, to form the inside of the side of the membrane 46 facing the needle guide element 38 with a defined roughness from the fuel supply channel 26 in order to produce a desired leak between the control chamber 48 and the high-pressure chamber 24 similar to the throttle passage 86. Instead of the throttle passage 86 and / or this leak, a defined larger clearance between the needle guide element 38 and the injection valve member 22 can also be selected in order to increase operational safety in the event that the actuator 62 should fail. It becomes with a time delay, pressure equalization with the high-pressure chamber 24 is established in the control chamber, which, if the actuator 62 fails, causes the injection valve member 22 to move into the closed position and, if the actuator 62 fails, continuous injection is avoided. Of course, the time constant for the pressure compensation is relatively long in relation to the duration of an injection process.

The injection valve member 22 could, as in the embodiments described above, be formed with a stop 54. For the sake of completeness, it should be mentioned that a compression spring 76, as in the embodiment according to FIG. 2, together with the throttle opening 86 or the defined leak between the high-pressure chamber 24 and the control chamber 48, in the embodiment according to FIG Failure of the actuator 62 can also increase.

The embodiment of the cup-shaped membrane 46 of FIG. 4 is quite favorable for the function at high fuel pressure, since the relatively thin membrane 46 is supported entirely on the front part of the actuator shaft 58 and thus, compared to the embodiments of FIGS. 1 to 3, none has a free area that cannot counteract the pressure force of the fuel.

The critical transition region 46c of the membrane 46 with a gradually increasing wall thickness from the thin-walled cylinder-jacket-shaped part 46a to the thicker region 46b standing vertically, which forms a flange, can also be supported on the actuator shaft 58. The flat front part 46d of the membrane 46 could also be thicker than shown in FIG. 4. If the membrane 46 is made from one piece, it is preferably produced as a deep-drawn part. The membrane 46 can also consist of several assembled parts.

For example, in the transition region 46c or in the vicinity thereof, the thin membrane head can be welded to the thicker region 46b. Likewise, the connection of the

(possibly thicker) front part 46d with the thinner part of the

Membrane 46 can be realized. Other types of connection of a multi-part membrane 46 are also conceivable. The other membranes 46 can also be made from several parts.

During operation of the fuel injector, the thinner cylindrical part 46a of the diaphragm 46 shortens or expands in the elastic region of the diaphragm material in accordance with the movement of the actuator shaft 58. With a steel membrane, strains of 20 to 30 micrometers per 10 mm membrane length can be achieved. If other materials are used, e.g. Titanium, titanium alloys or other special alloys, much larger, elastic expansions, up to or over twice, can be achieved.

If the membrane 46 is to be as extensible as possible, the actuator shaft 58 must also be as rigid as possible. This can be strongly influenced by a suitable choice of material. For example, instead of steel, an actuator shaft 58 made of ceramic material can be well suited.

In operation, a relative movement in the micro region results between the inner wall of the cylindrical part 46a of the membrane 46 and the peripheral surface of the actuator shaft 58. Here, the friction and wear must be minimized or avoided. This can be done, for example, by using suitable Feedings, material pairings or lubrication can be realized by means of the hydraulic fluid in space 63 (FIG. 1), coupled with corresponding small lubrication grooves, grooves, micro-lubrication pockets and the like on the circumferential surface of the actuator shaft 58.

In the embodiment according to FIG. 5, as in that according to FIG. 3, the longitudinal axes 80, 82 of the actuator arrangement 44 and of the injection valve member 22 are desaxed relative to one another. As in the embodiment according to FIG. 4, the valve seat element 16 is placed on the end face of the housing 10 and held on it by means of the union nut 84. A thick washer 88 with a passage is inserted between the housing 10 and the valve seat element 16. In the passage is the thick washer 56, which clamps the membrane 46 forming the sealing element 45 between itself and the end face of the valve seat element 16 u on the catch side. The annular disk 56 is supported on the housing 10 with its end face facing away from the membrane 46, like the intermediate disk 88. The membrane 46 in turn seals the control chamber 48 and thus the high-pressure chamber 24 from the actuator arrangement 44. In order to ensure that the sealing of the fuel supply channel 26 between the housing 10 and the intermediate washer 88 on the one hand, the intermediate washer 88 and the valve seat element 16 on the other hand and the control chamber 48 are possible at the same time, there must be the same surface pressures at the sealing points, which must be taken into account when designing the parts.

The needle guide 36 is formed on the valve seat element 16 and connects to the needle guide 36 on the side facing the injection valve seat 20 with a annular expansion of the recess in the valve seat element 16 of the high-pressure chamber 24, which in turn extends to the injection valve seat 20. The high-pressure chamber 24 is by means of the fuel supply channel 26, which extends in the valve seat element 16 from the extension to the intermediate disk 88 and from there parallel to the longitudinal axis 88 through the intermediate disk 88 and in the housing 10 to the high-pressure fuel inlet, not shown.

In the embodiment shown in FIG. 5, the needle guide 36, which in turn can be a close sliding fit, is formed on the valve seat element 16. In an analogous manner, it is possible to form the needle guide 36 on the housing 10. Otherwise, the mode of operation of the embodiment shown in FIG. 5 is the same as that according to the other embodiments described above.

The difference between the embodiment shown in FIG. 5 and the embodiment shown in FIG. 6 is that the washer 56 in FIG. 6 is thinner and is pressed against the membrane 46 by means of an eyebolt 42 which is screwed into the thick washer 88 to keep sealing against the end face of the valve seat element 16.

FIG. 7 shows a variant similar to the embodiment according to FIG. 4, but no needle guide element 38 and no control space 48 are present. The valve seat element 16 delimiting the high-pressure chamber 24 on the circumference and injection side lies sealingly on the flange-like, thicker region 46b of the sealing element 45 which forms it Membrane 46 and presses it, sealingly against the housing 10, under the action of the union nut 84.

The needle-like injection valve member 22, which is guided displaceably in the direction of the housing axis 12 by means of guide ribs 32 on the valve seat element 16, in turn passes through the high-pressure chamber 24 and, with its conical end region, cooperates with the injection valve seat 20 formed on the valve seat element 16.

The membrane 46 has an opening 90 in the region of the front part 46d, through which the injection valve member 22 extends. The membrane 46 is welded along this opening 90 to a shoulder surface 92 ′ of a thickening 92 of the injection valve member 22. The thickening 92 is thus arranged in the interior of the region delimited by the cup-shaped membrane 46 and separated from the high-pressure chamber 24 and interacts with its flat end face 50 with the end face 60 of the actuator shaft 58, which end face is also flat.

Otherwise, the membrane 46 and the actuator shaft 58 are of identical design and their interaction is identical to that shown in FIG. 4 and described above in connection with FIG. 4.

As a further embodiment with the same mode of operation as that shown in FIG. 7, it is possible to design the membrane 46 and the actuator shaft 58 as shown in FIG. 4, but the front part 46d of the membrane 46 is thick-walled and a blind hole-like central recess for the receptacle of the end region of the injection valve member 22 on this side. The injection valve member 22 is configured the same as shown in FIG. 4 and it is with the front part 46d of the membrane 46 welded. The front part 46d of the diaphragm 46 and the injection valve member 22 are thus, as in the embodiment according to FIG. 7, firmly connected to one another and move with one another in the direction of the housing axis 12. The diaphragm 46 delimits the high-pressure space 24 as shown in FIG. 7 close to the actuator arrangement 44. As can be seen from FIG. 7, the actuator shaft 58 and the thickening 92 of the injection valve member 22 have the same diameter and support the cylindrical, thin-walled jacket part 46a of the membrane 46. This is particularly long and therefore has an extra large extension length.

Due to the force of the actuator arrangement 44, the injection valve member 22 is held in a sealing arrangement on the injection valve seat 20. When an injection process is triggered, the actuator shaft 58 is moved in the direction away from the injection valve seat 20. The injection valve member 22 follows this movement directly as a result of the force exerted on the diaphragm 46 in the axial direction by the high-pressure fuel in the high-pressure chamber 24. To end the injection process, the actuator stem 58 and the injection valve member 22 are moved towards the injection valve seat 20 by means of the actuator 62 until the injection valve member 22 bears against it again.

FIG. 8 shows a further embodiment, which is very similar in structure to that of FIG. 4 and is identical in terms of functioning. The essential design difference is that the sealing element 45 is no longer designed as a continuous cup-shaped membrane 46, but as a membrane-like cup-shaped sealing element 45 without a pot bottom. The thin-walled, circular-cylindrical part 46a of the sealing element 45 lies flat and non-positively on the actuator shaft 58. The sealing and entrainment-proof concern is supported by the large pressure difference that prevails between the control chamber 48 and the side of the sealing element 45 facing away from the control chamber 48. This pressure difference presses the cylindrical part 46a of the sealing element 45 against the actuator shaft 58 with greater force. The actuator 62 is thus tightly separated from the control chamber 48 by means of the sealing element 45 and the actuator shaft 58.

The sealing element 45, like the membrane 46 in FIG. 4, is held with a thicker, flange-forming region 46b between the needle guide element 38 and the housing 10 in a sealing manner. In a transition area 46c, the wall thickness decreases continuously from area 46b to cylindrical part 46a; Seen in section, the sealing element in the transition region 46c has the shape of a wedge. When the actuator shaft 48 moves in the direction of the housing axis 12 - the stroke is small, as described above - the cylindrical part 46a moves with the actuator shaft 58, while the sealing element 46 bends in the transition region 46c.

Flat, corrugated or pot membranes can be used. Because magnetostrictive and electrostrictive

(Piezoelectric) actuators can perform a relatively small stroke with greater force, they are particularly suitable for interaction with membranes; due to the small stroke, these are subject to low dynamic loads, which contributes to a long service life, although the Pressure difference between the two sides of the membrane is very large.

Different types of actuators can also be used. In order to avoid losses, however, the injection valve member 22 is not controlled by the pilot valve.

Of course, it is conceivable to design the end region 34 of the injection valve member 22 even more strongly than shown in FIG. 5 as a double-acting piston.

If actuators 62 are used with a stroke that is greater than the stroke to be carried out by the injection valve member 22, the effective area ratios of the diaphragm 46 and the injection valve member 22 can be selected in embodiments with a control chamber 48 such that a stroke reduction occurs. The area ratios can optionally also be selected such that the stroke of the actuator shaft 58 corresponds to that of the injection valve member 22.

The fuel injection valves according to the invention shown do not have to have strong closing springs, such as known pilot valve-controlled fuel injection valves.

In particular, if closing springs are used, they can be used to press the needle guide element 38 delimiting the control space 48 in a sealing manner against the flange-like region 46b of the sealing element 45. This will be explained with reference to FIGS. 4 and 8. The closing spring would be supported at one end on the injection valve member 22 and at the other end on the needle guide element 38. This would be sleeve-shaped - without protruding in the radial direction Clamping flange - formed and would be supported with an annular end face on the area 46b of the sealing element 45. A tubular intermediate piece would be inserted between the region 46b and the valve seat element 16, which has a radial distance from the needle guide element 38 in order to ensure the flow connection between the fuel supply channel 26 and the high-pressure chamber 24. The area 46b would be pressed against the end face of the housing 10 in a sealing manner by means of the intermediate piece.

Claims

claims

1. Fuel injection valve for intermittent fuel injection into the combustion chamber of an internal combustion engine, with a housing (10), a high-pressure chamber (24) connected to a high-pressure fuel inlet (28) and delimited by an injection valve seat (20), a control chamber (48) intended for this purpose to be filled with fuel, a needle-shaped injection valve member (22) which is arranged in the high-pressure chamber (24) and which interacts on the one hand with the injection valve seat (20) and on the other hand in the manner of a piston in a sliding fit between the control chamber (48) and the high-pressure chamber (24) arranged needle guide (36) is slidably mounted, and an actuator arrangement (44) with an actuator which influences the pressure in the control chamber for controlling the movement of the injection valve member (22), characterized in that between the control chamber (48) and the Actuator (62)

Sealing element is arranged, which is the actuator

(62) keeps fuel free, is arranged with its annular flange with respect to the housing (10) tightly and tightly and is deflected for movement of the injection valve member (22) by means of the actuator arrangement (44).

2. Fuel injection valve according to claim 1, characterized in that the sealing element is a membrane

(46), which separates the control chamber (48) from the actuator arrangement (44).

3. Fuel injection valve according to claim 2, characterized in that the actuator arrangement (44) has an actuator shaft (58) which is actuated by the actuator (62) and which cooperates with an end face (60) with the membrane (46).

4. Fuel injection valve according to claim 2 or 3, characterized in that the membrane (46) is cup-shaped and the actuator stem

(38) engages in the membrane (46).

5. Fuel injection valve according to claim 1, characterized in that the sealing element is membrane-like and cup-shaped, but without a pot bottom, and the actuator arrangement (44) is one of the actuator

(62) actuated actuator shaft (58) which passes through the sealing element in a driving-tight and sealing manner.

6. Fuel injection valve according to one of claims 1 to 5, characterized in that the sealing element consists of at least two parts which are tightly connected to one another, in particular welded together.

7. Fuel injection valve according to one of claims 1 to 6, characterized in that the needle guide

(36) is formed on a valve seat element (16), on which the valve seat (20) is also formed and which surrounds the high-pressure chamber (24).

8. Fuel injection valve according to one of claims 1 to 6, characterized in that the needle guide

(36) is formed on a needle guide element (38) delimiting the control space (48).

9. Fuel injection valve according to one of claims 1 to 8, characterized in that the sliding fit is designed as a narrow sliding fit and between the control chamber (48) and the high-pressure chamber (24), outside the sliding fit, a throttle connection (86) is present ,

10. Fuel injection valve according to one of claims 1 to 9, characterized in that the injection valve member (22) with respect to the actuator arrangement (44) is desaxed.

11. Fuel injection valve according to one of claims 1 to 10, characterized in that the deflecting surface of the sealing element, possibly including the cross-sectional area of the part of the actuator shaft (38) penetrating through the sealing element, is larger than the cross-sectional area of the injection valve member interacting with the control chamber (48) (22).

12. Fuel injection valve according to one of claims 1 to 11, characterized in that the

Injection valve member (22) has a stop (54) which, in a maximum permissible open position of the injection valve member (22), interacts with a counter stop (52) which is fixedly arranged with respect to a housing (10).

13. Fuel injection valve according to claim 8, characterized in that the needle guide element (38) has a rib-like, projecting guide (38a, 38b) for centering it.

14. The fuel injector according to one of claims 1 to 13, characterized in that the actuator arrangement (44) has an electrically controlled piezoelectric or magnetostrictive actuator (62).