EP1915527B1 - Partially dethrottled injection valve member for fuel injectors - Google Patents

Description

The invention relates to a teilentdrosseltes injection valve member for fuel injectors, in particular for injector-controlled injectors, which are used in high-pressure accumulator injection systems.

State of the art

For injecting fuel into combustion chambers of self-igniting internal combustion engines, actuator-controlled fuel injectors are used whose injectors have a conically shaped seat in the nozzle body. The conical seat opens at a defined diameter, which is also referred to as a blind hole diameter, in a blind hole, from which then the injection openings of the nozzle are fed. In the case of alternatively used seat hole nozzles, on the other hand, the injection openings are not located in the abovementioned blind hole but at the level of a pointed cone of the injection valve member in the seat of the injector body.

The first-mentioned variant with a conical seat in the injector body has a geometric seat diameter (contact line injection valve member / injector body in the powerless state), at which the injection valve member at the end facing away from the injection openings adjoins a seat cone. In this area, the injection valve member has a smaller cone angle than the injector body. Towards the end of the injection valve member facing away from the injection openings, this seat cone is delimited on the injection valve member by a cylindrical projection of defined diameter. The distance that is established in the force and pressure-free state between the injection valve member and the injector body at an edge between the seat cone and said cylindrical projection is referred to as G0-measure. Below the geometric seat diameter at the injection valve member is an undercut with usually arcuate cross-section. Towards the combustion chamber-side end of the injection valve member, the tip cone follows on this undercut. In this area, the injection valve member has a larger cone angle than the injector body or nozzle body. Consequently, the gap between the injection valve member and the injector body continuously grows between the lower edge of the undercut and the blind hole diameter. The distance, which sets in the non-pressurized state between the injection valve member and the injector body at the blind hole diameter is referred to as G3-measure, the distance which is established at the transition between the undercut and the tip cone, referred to as G-measure.

In the closed state of the injection valve member engages between a guide diameter and the seat diameter of the injection valve member of the defined system pressure (pressure level in the high-pressure reservoir) and causes in this defined annular surface a defined acting on the injection valve member opening force. In contrast, the variable over the switching state of a switching valve control chamber pressure at the circular surface formed by the guide diameter causes a defined closing force on the needle-shaped injection valve member. In order to ensure the small quantity capability of the fuel injector despite the very stiff and therefore fast-reacting association between the control chamber and nozzle seat, the opening force may only be slightly larger than the stationary with the switching valve open adjusting closing force. To achieve this, the seat diameter is chosen only slightly smaller than that theoretical seat diameter, in which just after the opening of the switching valve, a balance of forces between opening and closing force, the injection valve member does not open. In order to ensure the opening of the needle-shaped injection valve member even if the injection valve member "digs" into its seat in the injector body or nozzle body, the diameter of the cylindrical projection must still be below the above-mentioned theoretical limit. It follows that the seat cone of the injection valve member builds very short in such fuel injectors.

When the injection valve member opens, a pressure arises within the blind hole which results from the interaction of seat throttling and throttling in the injection openings. Particularly in the case of small strokes, in which the needle opening dynamics are very sensitive to changes in the opening force, the pressure in the blind hole is comparatively low and the resulting fraction of the opening force is likewise.

Between the cylindrical projection and the blind hole diameter, a pressure field is formed whose course is dependent on the stroke of the injection valve member and the fine geometry of the gap between the injection valve member and the injector body or the nozzle body. This pressure field can change very much over the life of the injection valve member at the same stroke, since the fine geometry of the gap between the injection valve member to the body changes when the needle-shaped injection valve member during operation of the fuel injector successively in the nozzle body or in the injector body incorporated. Due to the very short seat cone (length 150 μm), the pressure field below this seat cone changes when the seat is worn Injection valve member only very little. In contrast, this pressure field undergoes a considerable change under the peak cone and consequently also in the undercut. The narrowest throttle cross section and thus the largest pressure gradient moves with increasing depth of wear more and more in the direction of the blind hole diameter. As a result, as the wear increases, the opening force acting on the injection valve member increases significantly, in each case with the same stroke of the injection valve member, which leads to a very undesirable increase in quantity, ie an increase in the amount of fuel injected into the combustion chamber.

To mitigate this effect, in DE 10 2004 013 600.9 proposed a fuel injection valve for internal combustion engines, in which the tip cone of the injection valve member is additionally provided with longitudinal laser grooves, so that limits even with complete contact between the injection valve member and the injector body or the nozzle body, the additional throttling in this area and thus the increase in volume over the life remains. The disadvantage, however, is that the tip cone according to this solution can no longer contribute to the sealing function of the injection valve member. With a completely supporting nozzle seat, well over half of the supporting surface is crossed by laser grooves and consequently can not contribute to the sealing function. This means that from a certain depth of wear leakage can occur, which is usually accompanied by an increase in the injection quantity.

It has been found that the depth of wear that occurs over the life of the injector is difficult to predict. This depends on many factors outside the injection valve, such as the load spectrum of the vehicle, the system pressure within a high-pressure injection system and, for example, the contamination of the fuel with dirt and water. In order to further reduce the wear, it is according to DE 10 2004 013 600.9 proposed to provide the seat of an injection valve member without changing the geometry with a wear protection layer. This reduces the wear of the counter body, in this case the injector or the nozzle body considerably. However, abrasion occurs on the wear protection layer itself. Due to the geometry optimized for operation without wear protection layer with a GO dimension which is considerably smaller than the G3 dimension, the wear protection layer is first removed on the seat cone and at the transition between the undercut and the top cone. In the area of the worn wear protection layer, the wear rate in the injector body or in the nozzle body initially increases considerably. As a result of this, when the injection valve member is closed, the surface pressure decreases below the region of the injection valve member which is no longer coated with the wear protection layer, while it clearly increases at the still coated region of the wear protection layer. By this effect, the wear rates are similar under the two now different areas the wear protection layer of the injection valve member slowly back to each other. The resulting gap geometry has in the powerless state an inhomogeneous seat gap between the injection valve member and the injector body. At low pressures, the injection valve member sits only on an annular transition between still existing and worn through wear protection layer. Since this area during operation of the fuel injector, ie approaches the end of the broken fiber laser tip cone, it comes inevitably even at very low wear depths to leakage and a significant increase in quantity. Although the wear protection layer considerably reduces the progress of wear on the nozzle body or on the injector body, precisely this property leads, in the case of the seat geometry used, to a significantly increased sensitivity of tightness and injection quantity as a function of the wear depth. The document DE 10 2004 013 600.9 describes the preamble of claim 1. To counteract this adverse effect, seat geometries are developed with which a coated with a wear protection layer seat of an injection valve member is optimized with respect to its drift behavior. In these seat geometries, the seat cone has been lengthened and the seat angle of the injection valve member has been reduced. Both measures cause an increase of the G0-measure, so that this optimized seat geometry is of the same order of magnitude as the G3-measure. This can avoid that the wear protection layer on the seat is prematurely completely rubbed through. On the contrary, an annular transition between still coated and already stripped regions now forms on both the tip cone and on the seat cone, so that the injection valve member rests on both annular transitions at low system pressures. Since the upper of these two transitions lies on the sealing seat cone, the injection valve member remains tight over the entire pressure range and prevents the increase in volume associated with leakage. However, this function is retained only as long as on both sealing surface portions of the injection valve member still cone sections are obtained with preserved wear protection layer. Once one of the sealing surface sections has completely lost its wear protection layer, there is only one transition between uncoated and coated area of the injection valve member, on which the injection valve member is seated at low pressures. If this area lies on the tip cone of the injection valve member, leakage and an increase in volume again occur. On the other hand, if the transition is on the seat cone, the injection valve member will remain tight, but a considerable decrease in volume will occur. Due to unavoidable manufacturing tolerances with respect to the cone angle on the injection valve member and on the injector or nozzle body, it can not be ensured that the wear protection layer applied there is used up at the same time both on the seat cone and on the tip cone. Consequently, there is still a risk of leakage and increase in volume or from a substantial decrease over a certain period of time.

Presentation of the invention

The object of the invention is to optimize the wear occurring over the service life of a fuel injector and to significantly reduce the risk of occurring leaks and an increase in volume or a significant decrease in quantity over the service life of the fuel injector.

Following the solution proposed by the invention, the seat angle of the injection valve member is selected to be greater than the seat angle in the injector body while the tip cone of the injection valve member is selected to be smaller than the seat angle in the injector or nozzle body. The previously executed undercut can be omitted, the cylindrical approach, however, remains. This results between the cylindrical projection and the blind hole diameter now a concave gap. The angles and lengths of the cone sections on the injection valve member are chosen so that this rests in a powerless state at the level of the cylindrical projection and adjusts a small gap at the blind hole diameter, whose height is referred to below as G3-measure. The G3 dimension is preferably dimensioned in such a way that, although it is very small, it is in any case greater than 0 when the manufacturing tolerances are utilized. The greatest distance between the injection valve member and the Injektor- or nozzle body is now at the height of the intersection between the seat cone and the tip cone within a concave gap between the injection valve member and the nozzle / injector body (G dimension).

With the proposed solution, the wear of the wear protection layer no longer begins at the two mutually facing ends of the cone sections of the injection valve member, but at the ends facing away from each other (blind hole diameter at the top cone and cylindrical projection on the seat cone). As a result, the two transition points between the existing and already worn wear protection layer no longer away from each other (divergent wear protection layer wear) but to move towards each other (converging wear protection layer wear).

This ensures in particular that both the seat cone and the tip cone completely lose their respective wear protection layer at the same time, since the two transitions described above will inevitably unite with each other at the intersection of seat cone and tip cone.

Alternatively, the angles and lengths of the conical sections can also be designed so that the seat of the injection valve member initially rests only at the blind hole inlet in the new state and has a gap on the cylindrical projection. Equally well, a transition dimensioning is possible in which arises depending on the actual value of the angle within their tolerances a support on the cylindrical approach or the blind hole diameter.

The tip cone of the injection valve member can be wholly or partially executed with a targeted out-of-roundness at the injection valve member or on the injector body or nozzle body (eg laser grooves in the injection valve member), which ensures a Entdrosselung this seating area even if the preferably needle-shaped injection valve member slowly into the Injektorkörper or ., incorporates the nozzle body. The de-throttled area ends securely before the intersection between the seat cone and the tip cone. Optionally, the beginning or the end of the de-throttled region can be marked by a circumferential groove in the injection valve member or in the injector or nozzle body in order to achieve a uniform flow of the Entschrosselten bodies.

On the other hand, if the seat is designed such that the injection valve member initially rests on the blind hole diameter, then instead of the tip cone the seat cone can be throttled and the tip cone assumes the sealing function. The intersection between seat cone and tip cone on the injection valve member may be provided with a radius or a defined edge break.

Instead of intersecting two cones, i. In the present case of the seat cone and the tip cone, the concave seat shape can also be brought about by any other contour of the injection valve member, through which a concave gap between injection valve member and injector body or nozzle body is formed. Preferably, the concave gap has no further local maxima in addition to the maximum of its gap height. The concave gap can also be created by a non-linear conical contour of the body seat. Instead of the wear protection layers used today, which are made of, for example, amorphous diamond-like carbon, other materials for forming the wear protection layer may also be used, e.g. Silicate layers on the body seat or nitriding layers in the body seat.

drawing

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

Figur 1

einen Schnitt durch eine geschlossene Einspritzdüse,

Figur 1.1

eine überhöhte Darstellung im Maßstab 50 : 1 der geschlossenen Einspritzdüse gemäß Figur 1,

Figur 2

eine Darstellung der Geometrie einer bezüglich ihres Driftverhaltens mit einer Verschleißschutzschicht optimierten Einsptizdüse,

Figur 3

die erfindungsgemäß vorgeschlagene Sitzgeometrie mit konkav verlaufendem Drosselspalt,

Figur 4

die erfindungsgemäß vorgeschlagene Sitzgeometrie an einem Kraftstoffinjektor,

Figur 5.1

einen Schnitt durch die Sitzgeometrie gemäß Figur 3 bei mäßigem Verschleiß,

Figur 5.2

einen Schnitt durch die erfindungsgemäße Sitzgeometrie gemäß Figur 3 bei weiter fortgeschrittenem Verschleiß und

Figur 6

die erfindungsgemäß vorgeschlagene Sitzgeometrie mit konkavem Drosselspalt im Zustand gemäß Figur 5.2, d.h. bei weiter fortgeschrittenem Verschleiß und dadurch erzieltem konvergierenden Verschleißschutzschicht-Verschleiß im geschlossenen Zustand.

It shows:

FIG. 1

a section through a closed injection nozzle,

Figure 1.1

an elevated representation in the scale 50: 1 of the closed injection nozzle according to FIG. 1 .

FIG. 2

a representation of the geometry of an optimized with respect to their drift behavior with a wear protection layer Einsickizdüse,

FIG. 3

the inventively proposed seat geometry with concave throttle gap,

FIG. 4

the seat geometry proposed according to the invention on a fuel injector,

Figure 5.1

a section through the seat geometry according to FIG. 3 with moderate wear,

Figure 5.2

a section through the seat geometry according to the invention according to FIG. 3 at more advanced wear and tear

FIG. 6

the inventively proposed seat geometry with concave throttle gap in the state according to Figure 5.2 ie, more advanced wear and resulting convergent wear-resistant coating wear when closed.

embodiments

The representation according to FIG. 1 is a section of a fuel injector 10 can be seen, which is constructed rotationally symmetrical to a symmetry axis 12. A preferably needle-shaped injection valve member 14 cooperates with an inner sealing surface 20 of a nozzle or injector body 18.

Figure 1.1 shows a reproduced in an elevation of 50: 1 detail view of FIG. 1 , With an elevation 24 of 50: 1, the injection valve member 14 is shown. This includes a tip cone 26 and a seat 30, between which an annular groove 16 or an undercut 28 are arranged.

In the region of a blind hole inlet 22, the tip cone 26 of the injection valve member 14 is at a distance G3 from the inner sealing surface 20 of the nozzle or injector body 18. The dimension G is the distance of the injection valve member 14 from the inner sealing surface 20 of the nozzle or injector body 18 in the area of the undercut 28 or the Annular groove 16 and the transition to the tip cone 26 identified while the measure G0, the distance between the injection valve member 14 and the inner sealing surface 20 of the nozzle or injector body 18 at the edge of the seat 30 to a cylindrical projection of the injection valve member 14 has.

The tip cone 26 has a first sealing surface 34, while the seat cone 30, on which the seat of the injection valve member 14 is formed in the nozzle or injector body 18, comprises a second sealing surface 36.

FIG. 2 shows a representation of the geometry of an optimized with respect to their drift behavior with a wear protection layer injector. Both the first sealing surface 34 from the tip cone 26 and the second sealing surface 36 on the seat cone 30 are provided with wear protection layers 40, 42. The wear protection layers 40, 42 are usually applied continuously on the entire surface of the injection valve member 14. The undercut 28 (annular groove 16) is usually co-coated.

Analogous to the representation of the Figure 1.1 are in the illustration according to FIG. 2 the distances G3, G0 and G entered. The first sealing surface 34 and the second sealing surface 36 according to the embodiment in FIG. 2 are provided with wear protection layers 40, 42. The wear protection layer 40, 42 is usually present continuously on the entire surface of the injection valve member 14, at least in the region of the seal. It may be a continuously applied layer, wherein also the undercut 28 is usually co-coated in the region of the annular groove 16. At the in FIG. 2 illustrated variant is such that in progressive wear between injection valve member 14 and nozzle or injector 18, a divergent wear of the wear protection layers 40 and 42 and the inner sealing surface 20 of the nozzle or injector body 18 occurs. This means that the new sealing edges, which respectively adjust according to wear of the wear-resistant layer 40, 42, gradually move away from one another.

FIG. 3 shows the inventively proposed seat geometry with a concave throttle gap.

According to the proposed solution, the cone angles of the tip cone 26 and the seat 30 are reversed, such as FIG. 4 is removable. The cone angle of the tip cone 26 is denoted by α, while the cone angle of the seat 30 is denoted by β. From the illustration according to FIG. 3 shows that the dimension G3 at the blind hole inlet 22 is substantially lower than in the FIG. 2 illustrated embodiment. In contrast, the dimension G at the transition between the tip cone 26 and seat 30 is considerably larger, compared with the dimension G in the embodiment according to FIG. 2 , so that at the in FIG. 3 illustrated embodiment, a concave throttle gap 70 by the sealing surface 20 and the nozzle or injector body and the lateral surface of the preferably needle-shaped injection valve member 14 sets.

The first sealing surface 34 on the tip cone 26 as well as the second sealing surface 36 on the seat cone 30 are each coated with a first continuous wear protection layer 40 and a second continuous wear protection layer 42. These wear protection layers may be made of, for example, amorphous, diamond-like carbon, or may also be applied to the body seat, for example, as silicate layers or nitriding layers. Hereinafter, first wear-resistant layer 40 or second wear-resistant layer 42 is understood to mean a wear protection layer applied continuously to tip cone 26 and seat cone 30, which also covers the transition region between tip cone 26 and seat cone 30 in the region of the undercut 28.

The undercut is omitted, a cylindrical projection 43 (see. FIG. 4 ) at the injection valve member 14 is maintained. Between the cylindrical projection 43 and the blind hole diameter 32 (see. FIG. 4 ) at the blind hole inlet 22, now results in a concave throttle gap 70. The cone angle α and β (see. FIG. 4 ) and lengths of the cone portions 26 and 30 are selected so that the injection valve member 14 rests in the powerless state at the level of the cylindrical projection 43 and at the blind hole diameter a small gap, whose height corresponds to the G3 measure adjusts. The G3 dimension is preferably dimensioned as small as possible, however, in such a way that, when the manufacturing tolerances are utilized, in each case it remains greater than zero. The greatest distance between the preferably needle-shaped injection valve member 14 and the nozzle or injector body 18 is now at the level of the intersection between seat 30 and tip cone 26 a; here lies the G-measure.

FIG. 4 shows a different representation of the geometric relationships according to FIG. 3 ,

Out FIG. 4 shows that the preferably needle-shaped injection valve member 14 has a pressure stage 44. Between the compression stage 44 and the seat 30, the cylindrical projection 43 extends.

The fuel injector 10 includes the injection valve member 14, on which runs below the seat 30 of the top cone 26. The tip cone 26 is formed at a cone angle α, which is smaller than the cone angle β, in which the inner sealing surface 20 of the nozzle or injector body 18 extends, with respect to the vertical.

The cone angle β, in which the seat cone 30 is formed, however, is chosen to be greater than the cone angle γ of the inner sealing surface 20 of the nozzle or injector body 18th

The lengths and the cone angles α, β of tip cone 26 and seat cone 30 are selected so that the preferably needle-shaped injection valve member 14 rests in the powerless state at the level of the cylindrical projection 43 on the inner sealing surface 20 of the nozzle or injector 18. It turns at the blind hole inlet 22, taking into account the blind hole diameter 32, the dimension G3. The greatest distance lies between the preferably needle-shaped injection valve member 14 and the inner sealing surface 20 of the nozzle or injector body 18 at the level of the intersection between the apex angle 26 and the seat cone 30. Here lies the G dimension.

The lateral surface of the tip cone 26 is provided with the first wear protection layer 40, while the lateral surface of the seat 30 is provided with the second wear protection layer 42. Both the first wear protection layer 40 and the second wear protection layer 42 are continuously applied to the tip cone 26 and seat 30 as a layer. The wear protection layer 40, 42 may be formed of amorphous, diamond-like carbon as well as a silicate or nitride layer. These surfaces define the concave gap 70 between the outer contour of the injection valve member 14 and the inner sealing surface 20 of the nozzle or injector body 18.

From the representations according to the Figures 5.1 and 5.2 In each case sections in excessive representation by the inventively designed injection valve member with the proposed tip cone and seat angle in different states of wear show.

The representation according to Figure 5.1 shows the inventively proposed injection valve member in a moderately worn condition.

The moderately worn condition is identified by reference numeral 48. 48.1 shows a wear profile on the outer contour of the injection valve member 14 in the region of the seat cone 30 and tip cone 26, while the reference numeral 48.2 marks the wear profile of the inner sealing surface 20 of the nozzle or injector body 18. From the illustration according to Figure 5.1 shows that in the moderately worn state 48, the injection valve member 14 has buried in the inner sealing surface 20 of the nozzle or injector body 20. In the inner sealing surface 20, a slope 52 has been formed and a corresponding edge of the seat 30 notch.

In contrast, the wear profile 48.1 of the injection valve member 14 is characterized in that the first sealing surface 34 has an abrasion region 50, as well as the second sealing surface 36 on the seat 30th

With respect to the inner sealing surface 20, a first annular width 60 is defined by the first bevel 52, which adjoins an intermediate annular surface 64. The notch in the inner sealing surface 20 in the region of the seat 30 defines a second annular width 62.

The in Figure 5.2 shown advanced wear, which is identified by reference numeral 54, is further advanced on the first sealing surface 34 of the apex cone 26 and on the second sealing surface 36 of the seat 30 of the needle-shaped injection valve member 14. The abrasion region 50 on the first sealing surface 34 as shown in FIG Figure 5.1 has, as in Figure 5.2 shown enlarged at the first sealing surface 34 on the abrasion region 56. The same applies analogously to the second sealing surface 36 of the seat cone 30. A wear profile 54.1 on the outer contour of the injection valve member 14 is characterized by larger wear regions 56 on the first sealing surface 34 and the second sealing surface 36.

In contrast, the forming on the inner sealing surface 20 of the nozzle or injector body 18 wear profile 54.2 characterized in that a second slope 58 above the blind hole inlet 22 is much more pronounced, whereas the intermediate ring surface 64 on the inner sealing surface 20 between the second slope 58 and by the seat 30 generated notch in the inner sealing surface 20 is substantially shorter. Compared to the representation according to Figure 5.1 As the wear progresses, the first ring width 60 continuously increases while the intermediate ring surface 64 continuously decreases. Compared to the illustration in Figure 5.1 the notch in the inner sealing surface 20 is deeper and the second ring width 62 is slightly increased.

The wear of the wear-resistant layers 40 and 42, according to the solution according to the invention, no longer starts at the two mutually facing ends of the tip cone 26 and the seat 30, but at the opposite ends, with respect to the tip cone 26 at the blind hole diameter 32 and with respect to the seat 30 below of the cylindrical approach. Consequently, the two transitions between still existing and already abraded wear protection layer 40, 42 no longer run away from each other (divergent C-layer wear), but according to the invention proposed solution to each other (converging wear protection layer wear). This ensures, in particular, that the seat cone 30 and the tip cone 26 completely lose their respective wear protection layers 40 and 42 at the same time, since the two transitions described above inevitably result in the intersection between seat 30 and tip cone 26 unite. This safely eliminates the risk of a single-sided needle seat.

FIG. 6 shows the inventively proposed injection valve member in the closed state in a state of wear, the in Figure 5.2 corresponds to the worn state shown.

From the illustration according to FIG. 6 shows that the preferably needle-shaped injection valve member 14 rests on the second slope 58 of the inner sealing surface 20 of the nozzle or injector body 18. At the first sealing surface 34 of the injection valve member 14 is still a residue 72 of the wear protection layer 40 in the region of the blind hole inlet 22. Above the intermediate ring surface 64, which has remained on the inner sealing surface 20 of the nozzle or injector body 18, there is still a remainder 74 of second wear protection layer 42. After complete removal of the wear protection layers 40 and 42 at the first sealing surface 34 and the second sealing surface 36, the first intermediate ring width 60 and the second intermediate ring width 62 unite at the inner sealing surface 20 of the nozzle or injector body 18 into a single annular surface. Im in FIG. 6 illustrated state, the injection valve member 14 is closed and sealed. Abrasion region 56 as shown in FIG Figure 5.2 on the first sealing surface 34 of the tip cone 26 lies on the second slope 58 on the inner sealing surface 20 (see also illustration according to FIG Figure 5.2 ) on.

The converging wear protection layer wear is in the figure sequence according to Figures 5.1 and 5.2 indicated by the arrow 76.

This indicates the wear of the wear protection layers 40 or 42 and the inner sealing surface 20 of the nozzle or injector body 18 occurring during operation.

Notwithstanding the in the FIGS. 3 to 6 shown geometries with respect to the length of the top cone 26 or seat 30 and the cone angle α, β These can also be designed so that the injection valve member 14 initially rests only at the blind hole 22 in new condition and the cylindrical approach, ie behind the seat 30 a gap having. Likewise, a transition dimensioning can be realized in which, depending on the actual value, the cone angle α or the cone angle β within its tolerance adjusts itself to the cylindrical projection above the seat 30 or the blind hole diameter 32.

The tip cone 26 of the injection valve member 14 may be wholly or partially executed with a targeted out-of-roundness at the injection valve member 14 and the nozzle or injector 18 be (eg laser grooves in the injection valve member 14), which ensures a Entschrosselung this seating area even when the injection valve member slowly into the inner sealing surface 20 of the nozzle body and the injector body 18 incorporated. However, the entsch throttled area must be sure before the intersection between the seat 30 ends with the top cone 26. Optionally, the beginning or the end of the de-throttled region, ie the region of the injection valve member 14 which is formed in a targeted out-of-roundness, by a circumferential groove in the preferably needle-shaped injection valve member 14 or in the nozzle or injector 18 are marked to a uniform Flow to the de-throttled points (eg shown as laser groove).

If the seat is designed such that the injection valve member 14 initially rests on the blind hole diameter 32, the seat cone 30 can be throttled in place of the tip cone 26 and the tip cone 26 can assume the sealing function. The intersection between the seat 30 and the top cone 26 may be provided with a radius or with a defined edge break.

Instead of intersecting two cones, in the present case the tip cone 26 with the seat 30, the concave seat shape can also be accomplished by any other contour of the injection valve member 14, which has a concave gap between the needle-shaped injection valve member 14 and the nozzle or injector body generated. Preferably, the concave gap 70 has no further local maxima in addition to the absolute maximum of its gap height. The concave gap 70 may also be created by a non-linear conical contour of the inner sealing surface 20. Instead of the materials for the wear protection layers 40 and 42, which are made of amorphous diamond-like carbon, other abrasion resistant materials can be used.

LIST OF REFERENCE NUMBERS

10 fuel injector tilglied 12 axis of symmetry 48.2 Wear profile inner sealing surface 14 Injection valve member 16 Ring groove (undercut) 50 abrasion area 18 Nozzle / injector 52 first slope 20 Inside sealing surface 54 Condition with advanced wear 22 Blind hole inlet (50: 1) 24 camber 54.1 Wear profile injection valve member 26 tip cone 28 undercut 54.2 Wear profile inner sealing edge 30 seat cone G3 Distance injection valve member Nozzle body / Inj ektorkörper at blind hole inlet 22 56 abrasion area 58 second slope 60 first ring width in the worn state 48 G0 Distance of injection valve member Nozzle body / Inj ektorkörper on edge seat cone 30 / cylindrical approach 62 second ring width in the worn state 48 64 Between annular surface G Distance injection valve member Nozzle body / injector body Undercut 28 / tip cone transition 26 66 first width intermediate ring surface 68 second width intermediate ring surface 32 Blind hole diameter 70 concave throttle gap 34 first sealing surface 72 Rest Wear protection layer 40 36 second sealing surface 38 double seat 74 Rest Wear protection layer 42 40 first wear protection layer 42 second wear protection layer 76 converging wear protection layer wear α 43 cylindrical approach α Cone angle tip cone 26 44 pressure stage β Cone angle seat cone 30 46 Injection port γ Cone angle inner sealing surface 20 48 Condition with moderate wear 48.1 Wear profile injection

Claims (12)

1. Fuel injector (10) for internal combustion engines, with an injection valve member (14) on which a seat cone (30) is formed, with which the injection valve member (14) interacts by means of a longitudinal movement with a sealing surface (20) formed on an injector body (18) and, in the process, opens up or closes a fuel flow to at least one injection opening, and the seat cone (30) is provided with an anti-wear layer (42), characterized in that a peak cone (26) having a cone angle α and the seat cone (30) having a cone angle β are formed at the combustion-chamber-side end of the injection valve member (14), wherein the cone angle β exceeds a cone angle γ of the sealing surface (20), and the cone angle α of the peak cone (26) is smaller than the cone angle γ of the sealing surface (20).
2. Fuel injector according to Claim 1, characterized in that cone surfaces of the seat cone (30) and of the peak cone (26) form a concave gap (70) with the sealing surface (20).
3. Fuel injector according to Claim 2, characterized in that the concave gap (70) extends between a blind hole inlet (22) in the injector body (18) and a transition point of the seat cone (30) to a cylindrical extension of the injection valve member (14).
4. Fuel injector according to Claim 3, characterized in that, in the closed state of the injection valve member (14), a maximum G of the distance between the injection valve member (14) and the injector body (18) lies on an intersecting point between the seat cone (30) and the peak cone (26).
5. Fuel injector according to Claim 3, characterized in that, in the closed state of the injection valve member (14), a small gap, provided by a distance G3>0, arises at the blind hole inlet (22), which is formed in a blind hole diameter (32), and the injection valve member (14).
6. Fuel injector according to Claim 4, characterized in that the intersecting point between the seat cone (30) and the peak cone (26) is provided with a radius or with a defined edge break.
7. Fuel injector according to Claim 1, characterized in that the peak cone (26) on the injection valve member (14) or the sealing surface (20) of the injector body (18) is entirely or partially formed with a deviation from a circular form.
8. Fuel injector according to Claim 4, characterized in that the concave gap (70) does not have, apart from the maximum of the distance G, any further local maxima of the distance between the injection valve member (14) and the injector body (18).
9. Fuel injector according to Claim 1, characterized in that, in the new state of the injection valve member (14), the latter rests with its peak cone (26) on a blind hole inlet (22) and the peak cone (26) instead of the seat cone (30) opens up or prevents the fuel flow.
10. Fuel injector according to Claim 7, characterized in that a region, provided with a deviation from a circular form, of the peak cone (26) ends before the intersecting point of the peak cone (26) with the seat cone (30) on the injection valve member (14), and the end of that region of the peak cone (26) which is provided with a deviation from a circular form is bounded by an encircling groove in the injection valve member (14) or in the injector body (18).
11. Fuel injector according to Claim 1, characterized in that the seat cone (30) and the peak cone (26) are each provided with anti-wear layers (40, 42), the wear of which during operation of the injection valve member (14) takes place in a manner converging towards each other starting from the mutually averted ends of the anti-wear layers (40, 42) on the seat cone (30) and peak cone (26).
12. Fuel injector according to Claim 11, characterized in that the wear of the first anti-wear layer (14) on the peak cone (26) begins starting from the blind hole inlet (22) and the wear of the second anti-wear layer (42) begins starting from the transition point between the seat cone (30) and a cylindrical extension of the injection valve member (14).

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