EP2035686B1 - Fuel injector - Google Patents

Abstract

The invention relates to a fuel injector for injecting fuel into a combustion chamber, having a solenoid valve for controlling a mini-servo valve. A movable armature can be placed in a sealing fashion on a valve seat in a lower armature chamber, wherein in addition, the mini-servo valve is held in an injector body and seals a control line against a flat seat. By means of the flat seat, during an actuation of the solenoid valve, the control line can be relieved of pressure from a high fuel pressure to a return pressure into at least one return line. A mechanism for reducing pressure oscillations are provided in the at least one return line, which includes at least one diaphragm cell which is held in a recess and which is placed in fluidic connection with the at least one return bore. A fuel injector with the mechanism for reducing pressure oscillations is therefore created in the at least one return line which operates without a leakage flow and has a simple and effective function.

Description

State of the art

The present invention relates to a fuel injector according to the preamble of claim 1.

Fuel injectors of the type of interest serve to control the fuel which is injected into the combustion chamber in an internal combustion engine. They are essentially composed of a solenoid valve and a miniservovalve, and actuate a nozzle needle whose opening and closing position is controlled by the solenoid valve, so that injection holes are opened and closed in the injector for injecting the fuel.

Out EP 1 617 072 A2 a fuel injector for injecting fuel into a combustion chamber with a solenoid valve is known in which upon actuation of the solenoid valve, a control line from a high-pressure fuel to a return pressure in a return line is relieved. In order to reduce pressure oscillations, a pressure oscillation damping device is provided which dampens pressure fluctuations arising during the termination of the fuel injection by the control of the high-pressure fuel in the low-pressure region. The pressure oscillation damping device is arranged outside of the fuel injector in the return line and has a diaphragm can as a damping element with a balloon-shaped or pillow-shaped elastically compressible membrane.

Another fuel injector is out of the DE 101 59 003 A1 known. Herein a force injector is disclosed, which is designed with a solenoid valve for controlling the miniservovalve with an armature which can be applied to a valve seat in the lower armature space. The lower armature space is in fluid communication via bores with a control pressure chamber, whereby leakage quantities occurring via at least one return borehole can be returned to a tank above the lower armature space. To when closing the valve seat by To avoid the anchor pressure oscillations or pressure fluctuations in the system of return bores below the valve seat, means for reducing these pressure oscillations in the lower armature space are provided. The means for reducing pressure fluctuations include recesses or internals to be machined in the lower armature space and an enlarged volume of the return bores or of the lower armature space. Thus, certain affected by the return of the leakage quantities sections in the solenoid valve and in the injection valve in its volume can be increased. Such an enlargement of the volume, with a defined outflow cross-section, results in a significant reduction of pressure oscillations, but the necessary injector-related volume can not be represented in the available installation space.

An essential disadvantage of the known designs of fuel injectors are those pressure oscillations that lead to different opening behavior of the Miniservoventils and thus can lead to volume fluctuations of the injected fuel. Pressure oscillations that propagate through communicating holes in the adjacent solenoid valve space and the magnetic spring space cause a quantity map ripple, which also can not be satisfactorily reduced or avoided by means of the increased fluid volumes. Furthermore, causes a high pressure level in the fuel return unacceptably high loads in fuel return hoses and increased costs for high-pressure resistant hoses. Cavitation damage caused by pressure oscillations and high flow velocities occurs in the leakage bore of the injector body.

To avoid excessive pressure and the bounce of the armature, which interferes with a clean closing behavior of the injection holes through the nozzle needle, an improper injection of the fuel in the final phase of the opening cycle is caused, which has a negative emission behavior of the internal combustion engine result.

From the DE 102 21 383 A1 are known pressure limiting devices for limiting occurring peak pressure values in the fluidic system of a fuel injector. These relate to a fuel injector which has a high-pressure fuel pump with a pump piston driven in a stroke movement, which delimits a pump working chamber which is connected to at least one fuel injector, through which fuel is injected into the combustion chamber of the internal combustion engine. In this case, at least one connection of the pump working space with a discharge region is controlled by an electrically actuated control valve. By the pressure limiting device, a connection of the pump working chamber is opened with a discharge area when a predetermined pressure in the pump working space is exceeded. The pressure limiting device has an elastically deformable membrane which is acted upon by the pressure prevailing in the pump working chamber and which opens the connection of the pump working chamber to the discharge region when the predetermined pressure in the pump working space is exceeded due to its elastic deformation.

However, a disadvantage of the proposed pressure limiting device is the outflow of the fuel into a discharge area, which forms the formation of a closed Systems, ie the integration of the pressure relief device in the closed fluidic system of the return bores without leakage current not possible.

It is therefore the object of the present invention to provide a fuel injector with means for reducing pressure oscillations in the at least one return line, which operates without leakage current and has a simple and effective function.

Disclosure of the invention

This object is achieved on the basis of a fuel injector according to the preamble of claim 1 in conjunction with its characterizing features. Advantageous developments of the invention are specified in the dependent claims.

The invention includes the technical teaching that the means for reducing pressure oscillations comprise at least one diaphragm can, which is accommodated in a recess which is fluidically connected to the at least one return bore.

The integration of a membrane can and the fluidic connection to the return bore have the advantage that the maximum fuel pressure is limited to the level of the maximum diaphragm clamping pressure, whereby the pressure oscillations can be reduced. As a result, the flow velocity in the return bore is limited due to the volume taken up or discharged by the membrane can, whereby smaller cross sections of the return bores can be realized. If the pressure in the recess increases, the internal volume decreases due to the deflection of the membrane shells of the diaphragm can. This effect limits the maximum pressure during the pressure oscillations. If the fuel pressure in the system of the return lines decreases, the diaphragm shells expand again due to the internal pressure within the diaphragm cell and additionally because of the elastic restoring force of the diaphragm shells, so that overall a smoothing of the pressure fluctuations and thus a smoothing of the quantity characteristic waviness can be achieved.

The return bores extend from the lower region of the flat seat into the region of the solenoid valve, wherein the portion of the return bore in the direction of the solenoid valve serves as a connecting line into the magnetic spring chamber. Due to the reduced pressure oscillations, the bounce behavior of the armature of the miniservovalve can be reduced or avoided, which enables an improved metering of the amount of fuel injected into the combustion chamber, and the closing behavior of the fuel injector in the final phase of the injection cycle is optimized. Due to the thus achieved improved quantification of the injected fuel quantity due to the minimized or avoided bounce behavior improved combustion of the fuel due to the optimized atomization of the fuel is reachable in the combustion chamber, resulting in a reduction of pollutant emissions.

The recess for receiving the diaphragm cell is advantageously designed as a circular depression in the wall of the injector, so that the diaphragm cell can be easily inserted from the outside into the recess formed as a recess. A connecting channel allows fluid communication between the return bore and the recess to provide fluid communication between the recess and the return bore.

The closure element seals in the form of a cover, the recess to the outside in the injector body, wherein the closure element may be formed as a circular disc-shaped lid, which is mechanically secured by means of a shaft securing ring in the injector body and fluidly pressure sealed by a ring seal.

The biasing member may be made of a thin sheet metal material as an elastic, plate spring-like, circular disk-shaped element, so that the pressure cell is clamped in the region of its circumference by the biasing member against the inside of the closure element. The diaphragm cell is constructed from two circular membrane shells, which are pressure-tight radially circumferentially joined together.

The joint connection can advantageously be designed as a welded joint, wherein the membrane box is radially radially positioned and biased in the region of the weld seam of the two membrane shells between the biasing member and the inside of the closure element. As a result, in the case of a pressure drop in the interior of the recess, the welded connection between the two diaphragm shells of the diaphragm cell is relieved.

A further embodiment of the invention provides that the recess for receiving the diaphragm cell is accommodated in a separate damper housing, wherein the damper housing is arranged on the injector housing and is fluidically connected to the return line. Depending on the geometric conditions of the design space of the fuel injector and the lack of integration of the diaphragm into the injector, the execution of the means for reducing pressure oscillations in a separate damper housing offers the possibility to arrange the diaphragm can outside the injector body, and the recess in which the diaphragm cell is added to fluidly connect to the system of return bores. Similar to the recess formed in the injector body, the damper housing comprises an interior which is formed by means of a closure element to a closed recess for receiving the diaphragm cell, wherein stops are provided which receive the diaphragm can on the circumference of the weld and radially center. At the closure element and the stop itself stop surfaces are provided which limit the stroke of the membrane shells of the diaphragm cell. Thus, overload, i. a plastic deformation of the membrane shells are avoided. The biasing element is designed to be adjustable in the embodiment of the damper housing, so that the stop, which is integrally formed on the biasing element, is adjustable.

Advantageously, the circular membrane shells have a concentric wave structure to increase the compliance. Due to the wave structure, the value of membrane cup deflection may be increased due to the lower compliance and thus the extended elastic range to maximize the maximum volume difference between a maximum pressure and a minimum pressure within the recess. The volume difference relates to the maximum or minimum volume of the interior of the diaphragm cell. The wave structure runs concentrically around the central axis of the circular membrane can and can For example, four wave peaks or troughs include. Concerning the arrangement of the membrane shells to form the membrane can each other on the one hand the opportunity is offered to arrange the two circular membrane shells mirror images of each other, so that the wave structure of the membrane shells against each other and the membrane cell has a symmetrical design. On the other hand, there is still the possibility that the two circular membrane shells to form the diaphragm cell are arranged parallel, ie in the same direction to each other, so that the wave structure of the membrane shell is rectilinear and the diaphragm cell has an asymmetrical design.

In the first case of the symmetrical design of the membrane can, the membrane shells can be formed equal to each other, so that a small parts variance can be achieved. The membrane shells can be welded in the mutually facing arrangement, so that the membrane box does not require a preferred installation direction due to their symmetry. On the other hand, based on the symmetrical arrangement of the membrane shells, a minimum distance results which leads to a minimum thickness of the membrane can and comprises a relatively large volume within the membrane can.

However, it is known that at a smaller volume within the diaphragm can, the final pressure at a given intake volume, ie the volume difference at maximum pressure and minimum pressure within the return bore, only slightly increases when the initial volume is large. However, the limited by the space in their outer diameter diaphragm cell can take under life conditions only a limited intake volume. From the typical external pressure-displacement-volume characteristic of the present fuel injector can be seen that the swallowing volume requirement decreases with increasing external pressure. The reduction of the initial volume causes a steeper characteristic of the external pressure over the swallowing volume, whereby a higher external pressure can be achieved at the given intake volume. As a result, a safe function is achieved even with small absorption volumes. Thus, the possibility exists that the contour of the membranes in the entire spring region have a small distance, which is made possible by an asymmetrical arrangement of the membrane shells. Due to the low output volume in the diaphragm cell and the resulting steeper pressure volume characteristic, the pressure force which the diaphragm can expands when the external pressure is reduced is reduced bulges, very quickly, whereby a lower load on the membrane shells and the weld in the uninstalled state or outside of the operation of the diaphragm cell is given.

A further advantageous embodiment of the present invention provides that the membrane can is filled with helium and has a gas pressure which is greater than the return pressure in the return line or in the recess connected to the return line. If helium is selected as the gas which fills the membrane can, the sealing of the membrane shells is reliably possible and at the same time leads to more favorable properties of the gas state change. Helium has a high adiabatic exponent, with a steeper pressure rise characteristic compared to the isothermal basic design in highly dynamic processes.

Advantageously, the diaphragm cell on a stroke limitation, which is introduced inside the diaphragm cell. The stroke limiter in this case comprises stirrup elements, which are arranged interlocking, so that this limits both the membrane shells merging membrane shell deflection and the membrane shells divergent Membranschalendurchbiegung. The stirrup elements can be welded into the membrane shells on the inside, and have a C-shaped profile structure, which in each case engage one another in opposite directions. If the membrane shells bulge outwards, the bending movement of the outer curvature is limited by engagement of the C-shaped profiles of the hoop elements, wherein the hoop elements have a height above the inner side of the membrane shells, which also limit a deflection of the membrane shells inward. Thus, the possibility is created by simple means to limit a stroke limitation both as a deflection inward and a bulge of the membrane shells to the outside, without providing external elements to the diaphragm cell. The stirrup elements in the respective membrane shell can be formed equal to one another in order to minimize the parts variance in this case as well, whereby an asymmetrical design of the elements of the stroke limitation within the membrane shells is also possible.

Further, measures improving the invention will be described in more detail below together with the description of preferred embodiments of the invention with reference to figures.

embodiments

• Figur 1: ein Querschnitt eines Kraftstoffinjektors mit Mitteln zur Druckbegrenzung, wobei die Mittel als Membrandose ausgebildet sind, die innerhalb des Injektorkörpers integriert sind;
• Figur 2: einen Querschnitt eines Ausschnitts der Membrandose aus Figur 1, welche innerhalb des Injektorkörpers integriert ist;
• Figur 2a: einen Querschnitt eines Ausschittes der Dämpferbaugruppe gemäß eines weiteren Ausführungsbeispiels;
• Figur 3: einen Querschnitt eines Kraftstoffinjektors mit Mitteln zur Druckbegrenzung, wobei die Mittel als Membrandose ausgebildet sind, die in einem außerhalb des Injektorkörpers angeordneten Dämpfergehäuse integriert sind;
• Figur 4: eine Membrandose gemäß vorliegenden Erfindung, welche eine innenseitig eingebrachte symmetrische Hubbegrenzung aufweist;
• Figur 5: ein weiteres Ausführungsbeispiel der Membrandose mit innenseitig eingebrachter Hubbegrenzung, wobei die Hubbegrenzung asymmetrisch ausgebildet ist;
• Figur 6a: ein erstes Ausführungsbeispiel der Membrandose, welche eine symmetrische Anordnung der Membranschalen aufweist; und
• Figur 6b: ein weiteres Ausführungsbeispiel der Membrandose, welche eine asymmetrische Anordnung der Membranschalen aufweist.

It shows:

• FIG. 1 a cross-section of a fuel injector with pressure-limiting means, the means being designed as a diaphragm can integrated within the injector body;
• FIG. 2 : a cross-section of a section of the membrane can FIG. 1 which is integrated within the injector body;
• FIG. 2a FIG. 3 is a cross-sectional view of a portion of the damper assembly according to another embodiment; FIG.
• FIG. 3 a cross-section of a fuel injector with pressure-limiting means, wherein the means are formed as a membrane can, which are integrated in a arranged outside the injector body damper housing;
• FIG. 4 a membrane can according to the present invention, which has an internally introduced symmetrical Hubbegrenzung;
• FIG. 5 : a further embodiment of the diaphragm cell with inside inserted Hubbegrenzung, wherein the stroke limitation is formed asymmetrically;
• FIG. 6a a first embodiment of the membrane can, which has a symmetrical arrangement of the membrane shells; and
• FIG. 6b : Another embodiment of the membrane can, which has an asymmetric arrangement of the membrane shells.

The in FIG. 1 The fuel injector 1 comprises an armature 3 and a valve seat 4, wherein the latter separates an armature space 5 from a control chamber of the miniservovalve 2. When the magnetic coil of the solenoid valve 1 is energized, the armature 3 moves upward in the vertical direction, so that the valve seat 4 in the lower armature space 5 opens. This valve seat 4 is in turn via one or more holes in fluid communication with a control pressure chamber of the miniservovalve 2. When opening the valve seat 4, the pressure in the control pressure chamber of the miniservoval valve decreases, fluid via the holes in the direction of the valve seat 4 from there into the lower Anchor space 5 flows. At a decreasing pressure in the control chamber, the nozzle needle (not shown here) of the fuel injector, which is constantly exposed to an acting in the opening direction of high pressure, set in motion, whereby the injection holes are opened and the fuel injector can inject fuel into the combustion chamber. In the injector body 7 return bores 8 are introduced, wherein the system of the return bores 8 connect to a flat seat 6, and wherein 6 pressure oscillations within the return bore 8 can occur due to the opening or closing movement of the flat seat. Therefore, these are fluidically connected to a recess 10 and act on a diaphragm cell 9, which is incorporated within the recess 10. The recess 10 is arranged on the outside in the injector body 7, and sealed pressure-tight by means of a closure element 12. If the injector on the flat seat 6 of the miniservovalve 2 now relieves the control line from rail pressure to return pressure, a high volume flow within the return bore 8 initially arises. This is passed on to the recess 10, so that the diaphragm can 9 is pressurized and the membrane shells are arched inwards , This reduces the inner volume of the diaphragm cell 9, and occurring pressure peaks within return bores 8 are reduced. If, on the other hand, the pressure within the return bore 8 drops, the membrane shells of the membrane can 9 expand again, so that overall the pressure fluctuations are smoothed out. The membrane box 9 is arranged between the closure element 12 and a biasing element 13, which press the membrane shells of the membrane box each on each other to relieve the weld between the membrane shells.

FIG. 2 shows an enlarged section of the recess 10 within the injector body 7. About the return bore 8, the recess 10 with the area below the flat seat (see FIG. 1 ) connected. Within the recess 10, the membrane box 9 is arranged, which is formed from a first membrane shell 14 and a second membrane shell 15. If the fuel then flows through the return bore 8 into the recess 10, it first passes into a first space 21, which passes through recesses 29 and 30 within the injector body 7 or the Closure element 12 is possible. A second space 22 is also pressurized with fuel pressure, which is directly connected to the return bore 8. Now increases the pressure within the spaces 21, 22, so the membrane shells 14 and 15 directed towards each other inwardly, so that the volume decreases within the diaphragm cell 9. The deflection of the membrane shells 14 and 15 is limited by a stroke limiter 16, which consists of a first bracket member 17 and a second bracket member 18. The ironing elements have a C-shaped profile, so that they each abut against the inside of the membrane shells 14, 15 and thereby limit the lifting movement. On the other hand, the bracket elements 17 and 18 engage each other when the pressure in the spaces 21, 22 decreases, and the membrane shells 14 and 15 bulge outwards. The membrane box 9 is clamped between a biasing member 13 and the closure member 12, wherein the clamping takes place radially circumferentially at the height of the weld 19 to relieve them due to the bias between the biasing member 13 and the closure member 12. For clearer representation is in the FIG. 2 the biasing element 13 is shown in a flying and unbiased condition. The closure element 12 is sealed by means of a sealing element 20 with respect to the outside of the injector body 7, which consists for example of an O-ring. In order to provide a limitation of the curvature movement of the membrane shells 14 and 15, stops 23 and 24 are provided both in the injector body 7 and in the closure element 12, to which the membrane shells 14 and 15 abut outwardly at a curvature of the membrane shells 14, 15. Thus set the biased stops 23, 24 of the stroke limitation the free-running pressure and limit outward Membranschalendurchbiegung. The inner stroke limiter 16 and the outer stroke limiter with the stops 23 and 24 are for simultaneous presentation both in the FIG. 2 shown, for a technical implementation of the arrangement one of the two stroke limits is sufficient. The stops are optionally formed by the housing 7 and the closure element 12 or by the biasing element 13 and the receiving element 28 (see FIG. 3 ).

FIG. 2a shows a further embodiment for receiving, limiting and biasing the diaphragm cell 9. The biasing member 13a has at least three exhibitions 32, which relieve the weld seam 19 by elastic bias and simultaneously hold the diaphragm cell 9 in position. Through the exhibitions 32 forms in the enclosure 31 a recess, whereby the space 22 directly and the Room 21 communicates with the return bore 8 via the recess 29a. At the closure lid side end of the enclosure 31, a latching 33 is formed, which preferably engages in the sealing ring groove of the closure element 12a and produces a positive connection. On the biasing element 13a, a stop 24a is formed, which cooperates with the closing element 12a formed on the stop 23a and can be used both for Loslaufdruckvorspannung and to the Hubbegrenzung. The latch 33 is secured by the boundary of the enclosure 31 in the recess 10. The diaphragm mount, which is independent of the injector body 7, permits precise pretensioning and idling pressure adjustment and stroke limitation to the outside. The damper assembly 34 provides a high process reliability, since the assembly is not hidden, no collision contours are present in the injector body and a lack of eg the diaphragm cell 9 is reliably detected. The comparatively sensitive diaphragm cell 9 is protected in the damper assembly 34 and independently testable. The damper assembly 34 consists of the closure element 12a, the membrane box 9, the biasing member 13a and the sealing member 20 and is pressure-tight received in the recess 10 of the injector body 7 to the outside, the diaphragm box is on all sides fluidly connected to the return bore 8 in combination. The circular disc-shaped biasing element 13a adopts both the preload to relieve the weld 29 and the function of the Loslaufdruckvorspannung and stroke limitation. The elastic bias is carried out by at least three flared areas, which lie close to the welding seam on the diaphragm cell.

FIG. 3 shows a further embodiment of the means for reducing pressure oscillations, wherein these comprise a diaphragm box 9, which is arranged within a damper housing 11. The damper housing 11 is in turn disposed on the injector body 7, and fluidly and mechanically connected thereto. According to the present exemplary embodiment, the mechanical connection comprises a screw connection, wherein the fluidic connection takes place via internal channels into the recess 10 within the damper housing 11 with the system of the return bore 8. The diaphragm cell 9 is received within the damper housing 11 and arranged by means of a closure element 12 in this fixed. Opposite the closure element 12, a receiving element 28 is provided, which is also formed circular disk-shaped and has a stop 25 in the center. Within the closure element 12, in turn, a further biasing element 27 is provided, which end in the direction of the diaphragm cell 9 has an opposite stop 26. Thus, the lifting movement of the membrane shells 14 and 15 of the diaphragm cell 9 can be limited by the stop 25 and 26. The closure element 12 is screwed inside the damper housing 11 and sealed pressure-tight by means of seals. The biasing member 27 is disposed centrally within the closure member 12 and designed as a kind of screw to adjust this by a screwing movement in the direction of the diaphragm cell 9 and removed to this. The centrally arranged stop 25 is formed on the receiving element 28 and acts counter to the abutment 26 of the biasing member 27. Thus, the maximum bulge of the diaphragm shells 14 and 15 can be limited.

In Figure 4 and 5 Each different embodiments of the stroke limiter 16 are shown in the diaphragm cell 9. In Figure 4 For example, the stroke limiter 16 has C-shaped bracket elements 17 and 18, which engage in one another in such a way that both an inwardly directed membrane deflection and an outwardly directed membrane deflection can be limited. On the other hand, the stroke limitation is in FIG. 5 formed asymmetrically, which is another embodiment of the same. This includes a T-shaped bracket member 17 and each bracket-shaped bracket elements 18, which also engage in such a way and limit an inwardly directed and an outward deflection of the diaphragm shells 14 and 15. The membrane shells 14 and 15 are joined together by a radially circumferential weld 19.

The Figures 6a and 6b each show a symmetrical and an asymmetric design of the membrane can 9. In FIG. 6a the membrane shells 14 and 15 are formed equal to each other, so that they are mirror images each rotated by 180 ° to each other and are welded together. By contrast, the membrane shells 14 and 15 according to FIG. 6b an asymmetrical design, so that the wave structure within the membrane shells are uniform and the overall height in the membrane box 9 is reduced. The membrane shells 14 and 15 each have three shafts, which are formed concentrically around the central axis of the membrane boxes 9, wherein also a different number of waves can be introduced into the membrane shells, which depends on the diameter of the membrane box and the thickness of the sheet material of the membrane shells , The wave structure enlarges the elastic region for bending the membrane shells 14 and 15, and substantially avoid damage or overloading of the membrane shells (14, 15) and the weld seam 19.

The invention is not limited in its execution to the above-mentioned preferred embodiment. Rather, a number of variants is conceivable, which makes use of the illustrated solution even with fundamentally different types of use.

Claims (8)

1. Fuel injector for injecting fuel into a combustion chamber, having a solenoid valve (1) which is provided for controlling a mini servo valve (2) and comprises a movable armature (3) which can be applied sealingly to a valve seat (4) in the lower armature chamber (5), wherein furthermore the mini servo valve (2) is held in an injector body (7) and seals off a control line with respect to a flat seat (6), by means of which, in the event of an actuation of the solenoid valve (1), the control line can be relieved of pressure, from a high fuel pressure to a return pressure, into at least one return line (8), with means for reducing pressure oscillations being provided in the at least one return line (8), and with the means for reducing pressure oscillations comprising at least one diaphragm capsule (9) which is held in a cutout (10), characterized in that the cutout (10) is placed in fluidic connection with the at least one return line (8) and is formed in the injector body (7) such that the diaphragm capsule (9) can be integrated in the injector body (7), and in that the cutout (10) is sealed off in a pressure-tight manner by means of a closure element (12), with a preload element (13) being provided in the cutout (10) adjacent to the diaphragm capsule (9), which preload element (13) mechanically braces the diaphragm capsule (9), on the joint circumference of the diaphragm shells (14, 15), against the closure element (12).
2. Fuel injector according to Claim 1,
   characterized in that the diaphragm capsule (9) has two circular-disc-shaped diaphragm shells (14, 15) which are joined to one another in a pressure-tight manner in a radially encircling fashion.
3. Fuel injector according to Claim 1,
   characterized in that the cutout (10) for holding the diaphragm capsule (9) is accommodated in a separate damper housing (11), with the damper housing (11) being arranged on the injector housing (7) and being fluidically connected to the return line (8).
4. Fuel injector according to Claim 1, 2 or 3,
   characterized in that the circular-disc-shaped diaphragm shells (14, 15) have a concentric corrugated structure in order to increase the flexibility of the diaphragm shells (14, 15).
5. Fuel injector according to Claim 4, characterized in that the circular-disc-shaped diaphragm shells (14, 15) for forming the diaphragm capsule (9) are mirror-symmetrical with respect to one another such that the corrugated structures of the diaphragm shells (14, 15) run oppositely to one another and the diaphragm capsule (9) has a symmetrical design.
6. Fuel injector according to Claim 4, characterized in that the circular-disc-shaped diaphragm shells (14, 15) for forming the diaphragm capsule (9) are arranged parallel to one another such that the corrugated structures of the diaphragm shells (14, 15) run in the same direction and the diaphragm capsule (9) has an asymmetrical design.
7. Fuel injector according to one of the preceding claims, characterized in that the diaphragm capsule (9) is filled with helium and has a gas pressure which is greater than the return pressure in the return line (8) and in the cutout (10) connected to the return line (8).
8. Fuel injector according to one of the preceding claims, characterized in that the diaphragm capsule (9) comprises a stroke-delimiting means (16) which is formed in the diaphragm capsule (9) at the inside.

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