EP1848891B1 - Sealing device for a fuel injector, and sealing method - Google Patents

Abstract

In order to create a fluid-tight seal relative to a seal seat edge (422), especially a cylinder head (40), in a sealing device for a fuel injector (1), particularly for a nozzle retaining nut (10) of the fuel injector (1), the sealing device has a sealing area (12) that is provided with a concave zone (122) having a radially circumferential concave outer contour (124) which can be made to sealingly rest against the seal seat edge (422).

Description

The invention relates to a sealing arrangement for a fuel injector, in particular the invention relates to a sealing arrangement for a nozzle retaining nut of a fuel injector, to ensure a fluid-tight connection between the fuel injector and a cylinder head. Furthermore, the invention relates to a nozzle retaining nut for a fuel injector.

A nozzle retaining nut holds the two main components of a fuel injector - an injector and a valve body - firmly together. The injection nozzle protrudes in the assembled state of the fuel injector in a cylinder head into a combustion chamber of an automobile engine, wherein the valve body arranged above actuates the injection nozzle. In this case, it is necessary to seal the fuel injector with respect to the combustion chamber on the cylinder head. This is done by a corresponding design of the nozzle retaining nut, which cooperates with a corresponding device, a sealing seat in the cylinder head.

At such a seal assembly high demands are made. On the one hand, it is exposed to high thermal loads, -40 ° C at cold start in winter to over + 150 ° C under operating conditions, and secondly high mechanical loads, in particular vibration loads. In addition, the seal assembly must ensure a durable sealing state between fuel injector and cylinder head with long-lasting loads.

For this purpose, in the prior art, for. B. on the nozzle retaining nut formed a horizontal edge, which is provided on a provided in the Injektorbohrung, also horizontal edge is seated, and the nozzle lock nut or the fuel injector is pressed with a large static force against the cylinder head. By providing a large surface coverage of the two edges, a permanently fluid-tight connection is to be created.

In such an arrangement, both sealing surfaces must be machined very accurately in order to get the connection ever fluid-tight. Due to the lateral play to be provided between the fuel injector and the injector bore, no centering between the fuel injector and the injector bore is possible with this design, so that this must be done by means of other inputs or devices.

In the DE 101 02 192 A1 has a nozzle retaining nut at a free end on a frusto-conical portion, which is insertable into a corresponding frusto-conical Injektorbohrungsabschnitt. In the preassembled state, ie when the fuel injector is inserted with nozzle retaining nut in the frusto-conical Injektorbohrung, there is a circumferential angle difference of 2 ° to max. Between truncated cone on the nozzle retaining nut and the truncated cone bore in the cylinder head. 5 °. As a result, a centering of the fuel injector is ensured in the Injektorbohrung, in which case the fuel injector is pressed with a large static force in the bore and forms a common sealing surface between the truncated cone on the nozzle retaining nut and the conical bore in the cylinder head.

The fact that the angular difference between the truncated cone on the nozzle retaining nut and the truncated cone bore in the cylinder head is only 2 ° to 5 °, there is a large areal coverage of the two sealing surfaces in the preassembled state, so that due to a clamping action between the two sealing surfaces self-centering only unsatisfactory forms , This problem is encountered in the prior art in that the corresponding surfaces, in particular the nozzle retaining nut is surface-coated to reduce the coefficient of sliding friction between the nozzle retaining nut and injector bore.

Despite improving the sliding friction between the fuel injector and injector bore, the angular difference of 2 ° to 5 ° is too small to prevent jamming and to ensure self-centering. By increasing the angular difference between the truncated cone on the nozzle retaining nut and the conical bore in the cylinder head to more than 5 ° smears would be made to the later seal quality, which can lead to leaks in the operation of the fuel injector.

The DE 101 02 192 A1 discloses fastener means for a fuel injector on a cylinder head, wherein the fuel injector within the cylinder head is surrounded by a sleeve which sealingly cooperates in cooperation with a sealing element of soft metal lying on a bottom of a stepped bore in the cylinder head.

It is an object of the invention to provide an improved seal arrangement for a fuel injector, as well as an improved nozzle lock nut. In particular, the fuel injector should have a good self-centering when mounted in the cylinder head and produce a permanently fluid-tight connection between the fuel injector and the cylinder head in cooperation with the cylinder head. This should preferably be done by means of the nozzle retaining nut of the fuel injector.

The object of the invention is achieved by means of a sealing device or a sealing arrangement for a cylinder head and a fuel injector, in particular for a nozzle retaining nut of the fuel injector and the cylinder head, wherein the one component has a radially preferably completely encircling, extending in a longitudinal direction, concave cross-sectional profile, which on / in a sealing surface or sealing edge of a second component fluid-sealing attachable / einpressbar is. Preferably, in this case, the nozzle retaining nut of the fuel injector is configured with a radial and completely circumferential concave chamfer. A sealing seat edge is horizontally extending within a stepped Injektorbohrung or tapered at an angle.

In this case, the concave chamfer and the sealing edge of the sealing seat edge interact in a special way. In a Vormontage- or centering state of the fuel injector is used with its nozzle lock nut in the Injektorbohrung without artificial forces acting on the fuel injector. In this case, the dimensions of the nozzle retaining nut and the injector bore are selected such that the concave region or the concave chamfer of the nozzle retaining nut is seated against the sealing edge of the sealing seat edge of the injector bore. A kinematic reversal, so Injektorbohrung with Konkavfase and nozzle retaining nut with preferably frustoconical sealing seat edge, of course, is equally applicable. Under certain circumstances, the materials from which the components are made to swap each other or you have to worry about their selection. The concave chamfer of the nozzle retaining nut sits only with a circle or a thin circular ring (centering state) on the edge of the sealing seat edge, as a result of which the nozzle clamping nut can not jam in the injector bore. Due to a low friction between the nozzle retaining nut and the cylinder head, the fuel injector is self-centering in the injector bore. In this case, the concave chamfer preferably has the lowest possible coefficient of adhesion and / or sliding friction, as a result of which self-centering is still favored.

Subsequently, the sealing state between the fuel injector and the cylinder head can be assumed. Here, the fuel injector is pressed with a large static force in the Injektorbohrung or the sealing seat, which is formed in the bore, whereby the preferably harder relative to the cylinder head concave area the sealing seat edge preferably plastically deformed and pressed into the sealing seat edge is that a fluid-tight connection between the nozzle lock nut and the cylinder head is made.

Due to the deformation of the sealing seat edge of the injector bore, a planar sealing section is formed between nozzle retaining nut and cylinder head, wherein due to the plastic deformation of the sealing seat rim, this adapts to the concave bevel and produces a high fluid pressure between the fuel injector and the cylinder head at high surface pressure. Furthermore, it is thereby possible to compensate for unevenness or small recesses in the surfaces. Such arrangements are permanently resistant to pressure undercurrents, so that a thermally and mechanically highly resilient seal assembly is realized with simultaneous long-term tightness.

According to the invention in a preferred embodiment, the angle in the centering between a tangent to a contact point between the seat edge and Konkavfase, with the radially outwardly extending sealing seat edge is about 10 °, resulting in a good self-centering of the fuel injector in the cylinder head. During the setting of the fuel injector in the cylinder head, wherein a deformation of the sealing seat edge happens, a tangent angle of a radially outer contact point between Konkavfase and sealing seat edge changes to the usual in the prior art 2 ° to 5 °. The cylinder head or the sealing seat edge here are usually made of aluminum or magnesium.

An additional surface treatment of the concave bevel results in this area in improved sliding properties of the nozzle retaining nut relative to the sealing seat edge or its edge, so that the fuel injector is positioned quickly and correctly oriented relative to the cylinder head in a simple manner.

Due to the provision of the concave chamfer results in particular in the further inner radial region of the sealing seat edge an increased specific surface pressure, whereby the seal between the fuel injector and the cylinder head is improved over the prior art. The highest surface pressure occurs at the inner region of the sealing seat edge, on which also the internal pressure of the combustion chamber rests; which is particularly advantageous, since a pressure infiltration can be effectively countered. Further, when impressing the Konkavfase in the sealing seat edge of the injector bore over the prior art, the voltage curve in the cylinder head is cheaper, resulting in fewer cracks in the cylinder head, which increases the durability of the cylinder head. Furthermore, conversely, the introduction of force into the nozzle retaining nut is optimized over the prior art, which likewise results in a more favorable stress curve within the nozzle retaining nut.

In a preferred embodiment of the invention, a connecting line, which in the centering state passes through the contact point of the concave chamfer with the sealing seat edge and through a peripheral point on the outer diameter of the concave region (in this case, the two points of the straight line and a longitudinal axis of the nozzle lock nut lie in one plane) a corresponding diametrically opposite straight line an angle of preferably about 108 ° or about 110 °. The radius of the preferably part-circular concave bevel is 55 mm ± 20 mm, in particular 55 mm ± 5 mm.

Furthermore, the invention relates to an engine and / or a cylinder head with a fuel injector according to the invention or a fuel injector with a nozzle retaining nut according to the invention.

In a method for centering and fluid-sealing a fuel injector or a nozzle lock nut relative to a cylinder head, the first component has a radial and preferably completely circumferential concave portion, which for a pre-assembly state to a sealing seat edge of the second component for centering the two components to each other is set. When the two components are transferred to a mounting state, the concave region moves under an elastic, but preferably plastic, deformation of the material of the sealing seat edge into the second component in such a way that between the concave region and the sealing seat edge common sealing surface arises due to a surface pressure, which is fluid-tight even at high internal pressures.

Further embodiments of the invention will become apparent from the remaining dependent claims.

Fig. 1a

eine erfindungsgemäße Dichtungsanordnung im vormontierten Zustand;

Fig. 1b

die Dichtungsanordnung aus Fig. 1a im montierten Zustand;

Fig. 2

eine Düsenspannmutter mit einer erfindungsgemäßen Dichtungseinrichtung;

Fig. 3a

die erfindungsgemäße Dichtungseinrichtung aus Fig. 2 in einem Zentrierzustand mit einem Zylinderkopf im Teilschnitt;

Fig. 3b

die erfindungsgemäße Dichtungseinrichtung aus Fig. 2 im Dichtzustand mit dem Zylinderkopf;

Fig. 4

den erfindungsgemäßen Dichtbereich der Düsenspannmutter aus Fig. 2 in vergrößerter Darstellung, sowie eine zusätzliche Detaildarstellung im Schnitt;

Fig. 5a

eine zweite Ausführungsform der erfindungsgemäßen Dichtungseinrichtung im Zentrierzustand im Teilschnitt; und

Fig. 5b

die zweite Ausführungsform der erfindungsgemäßen Dichtungseinrichtung aus Fig. 5a im Dichtzustand.

The invention will be explained below with reference to embodiments with reference to the accompanying drawings. In the drawing show:

Fig. 1a

a seal assembly according to the invention in the preassembled state;

Fig. 1b

the seal arrangement Fig. 1a in the assembled state;

Fig. 2

a nozzle retaining nut with a sealing device according to the invention;

Fig. 3a

the sealing device according to the invention Fig. 2 in a centering state with a cylinder head in partial section;

Fig. 3b

the sealing device according to the invention Fig. 2 in the sealing state with the cylinder head;

Fig. 4

the sealing region of the nozzle lock nut according to the invention Fig. 2 in an enlarged view, as well as an additional detail in section;

Fig. 5a

a second embodiment of the sealing device according to the invention in the centering in partial section; and

Fig. 5b

the second embodiment of the sealing device according to the invention Fig. 5a in the sealing state.

If position information such as "top" or "bottom" or "right" or "left" are made below, these refer to Fig. 2 in which a nozzle retaining nut 10 is cut to the right and is not shown cut on the left, the nozzle retaining nut 10 bracing an injection nozzle 20 arranged at the bottom with a valve body 30 arranged at the top.

The Fig. 1a and 1b show a seal assembly according to the invention, in particular for permanent and high-pressure fluid tightness of two components 10 and 40, z. B. a nozzle retaining nut 10 and a cylinder head 40th

The Fig. 1a represents a preassembled state of the two components 10, 40, wherein the component 10 relative to the component 40 preferably centered itself, therefore, this pre-assembly is also called centering. However, a self-centering of the two components 10, 40 to one another is not absolutely necessary for the invention; It is sufficient if the first component 10 can be attached to the second component 40, without a mutual self-centering. However, if a mutual centering is necessary, but self-centering is not possible, this should be done by external means.

For centering and sealing, the first component 10 has a concave region 122, and the second component 40 has a sealing seat edge 422. In the preassembled state of the two components 10, 40, the concave portion 122 is seated with a central portion at the edge 424 of the sealing seat edge 422. In the Fig. 1a and 1b If the center portion of the concave portion 122 is to be seen only as a point or a small area (contact point between the concave portion 122 and sealing seat edge 422), for the preferred rotationally symmetric component 10, this is idealized a circle or a thin circular ring. A seating of the smallest diameter of the concave portion 122 (lower edge on the component 10) on the sealing seat edge 422 (see also Fig. 5a and b) is also possible (further embodiment).

In a sealing state of the two components 10, 40, the in Fig. 1b is shown, a portion of the concave portion 122, by at least elastic, preferably plastic deformation of the material of the second member 40 in the sealing seat edge 422 impressed or pressed. The impressions of the first component 10 in the second component 40 takes place in a portion of the edge 424 of the sealing seat edge 422 radially outward from a longitudinal axis L of the seal assembly path. The deformation of the second member 40 is indicated by a broken line in FIG Fig. 1b indicated. By means of this bulge bulging radially inwards along the concave region 122, the sealing surface between the two components 10, 40 is additionally increased, which increases the fluid-tightness of the two components 10, 40.

The Fig. 2 to 4 show a first preferred embodiment of the seal assembly according to the invention, wherein the seal assembly according to the invention is adapted to a nozzle retaining nut 10 and a cylinder head 40 associated therewith. The sealing arrangement according to the invention serves to seal a fuel injector 1 preferably via its nozzle retaining nut 10 in an injector bore 42 of the cylinder head 40 with respect to a combustion chamber of an internal combustion engine.

A sealing device according to the invention is preferably located at the lower free end of the nozzle lock nut 10, which clamps together an injection nozzle 20 with a valve body 30 and combines them to form a fuel injector 1 (see FIG. Fig. 2 ); However, the sealing device according to the invention can also be provided on the fuel injector 1 itself, the nozzle retaining nut 10 then assumes no or only other sealing tasks for the fuel injector 1. This first embodiment of the sealing device on the nozzle retaining nut 10 comes with a sealing seat in the injector bore 42 (FIG. Fig. 3a and 3b ) to the plant, said sealing means and sealing seat together according to the principle of the invention according to the Fig. 1a and 1b interact.

In the embodiment according to the invention, a sealing or centering region 12 of the nozzle retaining nut 10 is preferably constructed in two parts. In the case of the nozzle retaining nut 10, a frusto-conical region 126 follows from below when approaching a concave region 122. Concave portion 122 and truncated cone portion 126 serve the nozzle retaining nut 10 and the fuel injector 1 in the injector bore 42 (FIGS. Fig. 3a and 3b ), wherein the concave portion 122 designed to is to center the nozzle retaining nut 10 at a sealing seat edge 422 of the injector bore 42 in the centering or pre-assembly state. Preferably, the nozzle retaining nut 10 is constructed radially symmetrical, wherein the concave portion 122 has a radially extending and fully encircling Konkavfase 124 which extends with its cross-sectional profile in the longitudinal or axial direction L of the nozzle lock nut 10 upwards. However, the nozzle lock nut 10 may also be constructed so that the truncated cone portion 126 is absent and at the lower, substantially conical portion of the nozzle lock nut 10, only the concave portion 122 is present. At the top of the sealing region 12 of the nozzle retaining nut 10, a cylinder region 14 of the nozzle retaining nut 10 adjoins above, in which mainly the valve body 30 is received.

In the centering state of the nozzle retaining nut 10 or the fuel injector 1, which in Fig. 3a is represented, the concave chamfer 124 or the concave portion 122 is seated on an edge 424 of a sealing seat edge 422. The edge 424 of the sealing seat rim 422 essentially describes a circle or a thin circular ring on the concave chamfer 124. The more circular (in one plane) this section on the concave chamfer 124, the more centered the nozzle chuck nut 10 sits in the injector bore 42 of the cylinder head 40 ,

The injector bore 42 is preferably a stepped circular cylinder bore, whose lower portion of smaller diameter receives a portion of the injection nozzle 20 and the upper diameter larger portion of the nozzle retaining nut 10 of the fuel injector 1. Both regions are preferably connected via a cone or a circular ring bevel (referred to below as truncated cone region 426); however, it is also possible to have a horizontal step which forms a right angle with the respective section of the injector bore 42.

In the centering state, the contact point M (sectional view of the Fig. 3a ) or the Berührkreis (ring) M (Realsituation with fuel injector 1) centered in injector bore 42, from edge 424 and concave chamfer 124 between a circumferential point (circumferential) circle (ring) I to the (lower) inner diameter D _I ( Fig. 4 ) of the concave chamfer 124 and a circumferential point / circle (ring). A with the (upper) outer diameter D _{A of} the concave chamfer 124, wherein preferably the contact point M is within the first third or within the first half of the path from the peripheral point I to the peripheral point A.

In the following, only from the points M, I and A, and no longer from the corresponding circles or circular rings the speech, but it should also be the circles or Berührkreisringe meant. Furthermore, in the following geometric details, such as. B. angle information and information on layers of straight lines, on levels in which the longitudinal or axial axis L of the nozzle retaining nut 10 is included, in particular falls to be considered level with the plane of the Fig. 4 together.

The sealing seat edge 422 of the injector bore 42 is preferably an inner portion of the truncated cone portion 426 of the injector bore 42, wherein the truncated cone portion 426 with the truncated cone portion 126 of the nozzle lock nut 10 has a circumferential opening angle of about 0.5 ° to 5 ° (ideal centering - that of all Points M formed circle is perpendicular to L). Other angle relationships as in Fig. 3a are shown in the explanation of Fig. 4 given.

The Fig. 3b shows a sealing state of nozzle retaining nut 10 and cylinder head 40, wherein the nozzle lock nut 10 is pressed into the sealing seat edge 422 of the injector bore 42 with a preferably plastic deformation of the sealing seat edge 422. In turn, deformation of the inner sealing seat edge 422 preferably takes place inwardly (see description of FIG Fig. 1b ). Ideally, a circular surface pressure with a high, uniform circular ring thickness and the highest possible surface pressure out, which has no points of discontinuity in the pressing. Preferably, the outer diameter edge (A) of the concave chamfer 124 does not dive straight into the truncated cone region 426 or the sealing seat edge 422.

Fig. 4 shows the sealing portion 12 of the nozzle lock nut 10 which is divided into truncated cone portion 126 and concave portion 122 in detail. Here, the truncated cone portion 126 and the concave portion 122 have a common circle in the Fig. 4 among other things in point A can be seen. This is at the same time a circumferential circle point A of the largest outer diameter D _{A of} the concave region 122. If one follows now from the point A of the concave chamfer 124 down the concave region 122 (and inwards towards L), one moves on the concave chamfer 124 via the contact point M of FIG Concave chamfer 124 and edge 424 (in the centering state) to the circumferential circle point I to the smallest inner diameter D _{I of} the concave 122. In a preferred embodiment of the invention, D _A = 13mm, wherein in the centering the diameter D _{M of} a circle formed by the point M about 10 , 9mm. Here, as already mentioned above, the point M is located on the first third or the first half of the way from point I to point A.

The concave chamfer 124 is preferably formed part-circular, wherein the radius R can vary between 20mm and 100mm. In a preferred embodiment of the invention, the radius of the concave chamfer 124 is 55 55 ± 5 mm. Correspondingly different radii arise when applying the inventive idea to other components; In principle, it is important that it is a concave contour. Not part-circular contours, which differ from a simple truncated cone, are also possible according to the invention. In particular, continuous transitions at the edges of the concave chamfer at I and A in the other regions of the nozzle lock nut 10 are advantageous because the voltage curve in the nozzle lock nut 10 and the introduction of force at the edges (I, A) of the cone chamfer 124 in the truncated cone portion 426 are cheaper and do not change so abruptly what z. B. a Klotoide is suitable.

The following angle specifications for the sealing device according to the invention relate to an inner opening angle of a cone which is formed by a line rotating about the longitudinal axis L of the nozzle retaining nut 10. In this case, such a straight line T _{M is} the tangent to the point M in the centering state of the nozzle retaining nut 10, the opening angle α _{M of} the cone in the centering state preferably being between 104 ° and 110 °, depending on the radius R of the concave chamfer 124. A corresponding angle α _{A of} the tangent T _A at the point A is preferably between 107 ° and 113 °, again depending on the radius R of the concave chamfer 124. An angle β of a connecting line MA of the points M and A is preferably 106 ° to 112 °. All of these details are related to a point M, which adjusts itself in the centering state of the nozzle retaining nut 10. The point M begins when the nozzle retaining nut 10 is pressed into the cylinder head 40 along the concave chamfer 124 in the direction of the point A (and of course linearly along the sealing seat edge 422) (point Mn), with a straight line MnA of the tangent T _A becoming more and more approaches. This is detailed in the sectional view of the Fig. 4 clarified. Mn is a radially outermost point of contact between concave chamfer 124 and sealing seat edge 422

Further embodiments according to the invention, which are based on the above, are given in the table by the following parameters: Cone angle of the rotating
Connecting line MA β = 108 ° β = 110 ° ∅ [mm] R = 35 R = 85 R = 35 R = 85 D _M = 10.9 (α _M ) 105.9 ° 107.1 ° 107.9 ° 109.1 ° D _Mn = 12.0 (α _Mn ) 108.1 ° 108.0 ° 110.1 ° 110.0 ° D _A = 13, 0 (α _A ) 110.1 ° 108.9 ° 112.1 ° 110.9 °

Here, the variables refer to the Fig. 4 , where, with Mn = 12.0mm, a value in moving M to A between M and A on the concave chamfer 124 is exemplified in the table.

The Fig. 5a shows a second embodiment of the sealing device according to the invention for the fuel injector 1 and the nozzle lock nut 10, wherein not the concave chamfer 124 at the edge 424 of the sealing seat edge 422 centered, but the lower edge of the sealing seat edge 422. This has the advantage that the injector bore 42 in diameter can be made smaller and can come closer to the injection nozzle 20 of the fuel injector 1. Optionally, the upper edge of the concave chamfer 124 may also be seated alone on the sealing seat edge 422 (circle (ring) A, largest diameter of the concave chamfer 124). Furthermore, it is also possible that in the centering state both circular edges I and A rest on the sealing seat edge 422, which has the advantage that a centering position of the two components can be checked such that the centering position is only assumed if both circular edges I and A completely against the sealing seat edge 422.

The sealing state shows Fig. 5b , wherein the two circles or circular edges I and A are pressed into the sealing seat edge 422 of the cylinder head 40 and form two sealing regions in the illustrated case. The firmer the nozzle retaining nut 10 is pressed into the cylinder head 40, the lower the remaining space between the nozzle retaining nut 10 and cylinder head 40. Other configurations of the sealing state, in which z. B. imprint only the lowest circle edge I or only the top circle edge A in the sealing seat edge 422.

Preferably, there is no cavity between the nozzle retaining nut 10 and the cylinder head 40. In the realization of such a sealing arrangement, it may be necessary to provide a vent of the initially existing cavity. Preferably, this vent closes automatically by the Pressing the nozzle lock nut 10 in the cylinder head 40. This can, for. B. done by a groove in the cylinder head 40 or in the nozzle lock nut 10, in which material of the nozzle retaining nut 10 and material of the cylinder head 40 penetrates during insertion. Furthermore, holes are suitable which can be closed in a similar way.

The preceding embodiments, which relate to the nozzle retaining nut 10 should also apply to the fuel injector 1, which is not sealed by means of its nozzle retaining nut 10 relative to the cylinder head 40, but having the device according to the invention at another section. The inventive device on the fuel injector 1 and a corresponding sealing seat on or in the cylinder head then together form the sealing arrangement according to the invention.

Claims (17)

1. Sealing arrangement for a nozzle tension nut (10) of a fuel injector (1) and for a cylinder head, for fluid-tight sealing with respect to a sealing-seat margin (422), with a sealing region (12) on the nozzle tension nut (10) or the cylinder head (40), characterized in that the sealing region (12) has a concave region (122) with a radial peripheral concave outer contour (124) which can be brought to bear sealingly against the sealing-seat margin (422) of the cylinder head (40) or of the nozzle tension nut (10).
2. Nozzle tension nut for a fuel injector (1), with a sealing region (12) for fluid-tight sealing with respect to a sealing-seat margin (422) of a cylinder head (40), characterized in that the sealing region (12) has a concave region (122) with a radial peripheral concave outer contour (124) which can be brought to bear sealingly against the sealing-seat margin (422) of the cylinder head (40).
3. Sealing arrangement or a nozzle tension nut according to Claim 1 or 2, the concave region (122) being configured with a fully peripheral concave chamfer (124), and a radially running frustoconical region (126) adjoining the concave region (122).
4. Sealing arrangement or nozzle tension nut according to one of Claims 1 to 3, in a centring state the concave region (122) being placed onto the sealing-seat margin (422), and a peripheral circular portion of the concave chamfer (124) being seated on an edge (424) of the sealing-seat margin (422).
5. Sealing arrangement or a nozzle tension nut according to one of Claims 1 to 4, in a sealing state the concave region (122) being connected fixedly to the sealing-seat margin (422), the concave region (122) being pressed into the sealing-seat margin (422) as a result of an at least elastic, preferably plastic deformation of the sealing-seat margin (422).
6. Sealing arrangement or a nozzle tension nut according to one of Claims 1 to 5, the concave chamfer (124) being formed radially and peripherally on a sealing face of the nozzle tension nut (10) which is seated so as to bear on a sealing-seat margin (422) of an injector bore (42) of the cylinder head (40).
7. Sealing arrangement or nozzle tension nut according to one of Claims 1 to 6, in the centring state the angle between the sealing-seat margin (422) and a tangent to a contact point (M) of the concave chamfer (124) and edge (424) amounting to 14 ± 2°, preferably 10 ± 1°, particularly preferably 7 ± 1°.
8. Sealing arrangement or nozzle tension nut according to one of Claims 1 to 7, at least one portion, extending in the longitudinal direction (L) of the fuel injector (1), of the concave region (122) cooperating, in the sealing state, with the sealing-seat margin (422) of the injector bore (42) in such a way that the fuel injector (1) is secured, fluid-tight, with respect to the cylinder head (40).
9. Sealing arrangement or nozzle tension nut according to one of Claims 1 to 8, in the sealing state the angle between the tangent (T_M) to a radially outermost contact point (M) between the concave chamfer (124) and sealing-seat margin (422) amounting to 7 ± 1°, preferably 4 ± 1°, particularly preferably 2 ± 0.5°.
10. Sealing arrangement or nozzle tension nut according to one of Claims 3 to 9, the sealing-seat margin (422) being designed as a frustoconical cone margin, the aperture angle of which is larger than an angle which the frustoconical region (126) of the sealing region forms, the aperture angle between the two amounting to 0.5° to 5°, in particular to 1° to 4°, preferably 2 ± 0.5°.
11. Sealing arrangement or nozzle tension nut according to one of Claims 1 to 10, in the centring state a contact point (M) of the concave chamfer (124) and edge (424) and an outside diameter point (A) of the concave chamfer (124) forming a connecting straight line (MA) which assumes with the longitudinal axis (L) of the fuel injector (1) an angle of 50° to 60°, in particular of 52° to 58°, preferably of 53° to 56°, and particularly preferably of 54° to 55°.
12. Sealing arrangement or nozzle tension nut according to one of Claims 1 to 11, a profile of the concave chamfer (122) being part-circular and having a radius (R) of 30 mm to 90 mm, in particular of 45 mm to 65 mm, preferably of 50 mm to 60 mm, and particularly preferably of 55 ± 2.5 mm.
13. Sealing arrangement or nozzle tension nut according to one of Claims 1 to 12, the face of the concave chamfer (122) being polished, preferably by means of a shot-peening method.
14. Sealing arrangement or nozzle tension nut according to one of Claims 1 to 13, the material of the sealing-seat margin (422), preferably aluminium, being softer than the material of the concave region (122) which is preferably produced from steel.
15. Sealing arrangement or nozzle tension nut according to one of Claims 1 to 14, the inner contour which lies opposite the concave chamfer (122) of the nozzle tension nut (10) being of convex design.
16. Fuel injector, in particular diesel injector, having a nozzle tension nut (10) according to one of Claims 1 to 15.
17. Engine or cylinder head with a fuel injector (1) according to Claim 16, the concave region (122) of the nozzle tension nut (10) being seated on the edge (424) of the sealing-seat margin (422) of the cylinder-head bore (42).

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