Injector for injecting a gaseous medium

Abstract

The present invention relates to an injector (1) for injecting a gaseous medium, in particular a gaseous fuel, preferably hydrogen, into a combustion chamber (20) of an internal combustion engine. The injector (1) comprises, inter alia, an axially movable valve-closing element (5) for opening and closing at least one opening at a sealing seat (7), an actuator (21) for actuating the valve-closing element (5), and a flow-influencing geometry (10) arranged downstream of the sealing seat (7) in terms of flow. According to the invention, the flow-influencing geometry (10) is designed in such a manner that, at a maximum needle stroke (lh) of the valve-closing element (5), the following relationship applies: 5 x lh ≥ s ≥ 1.5 x lh, wherein (s) is the distance between the radially outer contour of the valve-closing element (5) at the downstream edge region thereof and the annular line lying axially in a projection therebelow on a portion (12), tapering in the flow direction, of the flow-influencing geometry (10), in order to generate a virtually loss-free flow downstream of the valve-closing element (5).

Description

[0001] Description

[0002] title Medium

[0003] State of the art

[0004] The present invention relates to an injector for injecting a gaseous medium, in particular a gaseous fuel, into the combustion chamber of an internal combustion engine. Specifically, the invention relates to an injector with which hydrogen can be injected directly into the combustion chamber of a mixture-compressing, spark-ignition internal combustion engine.

[0005] Gas injectors are known from the state of the art in various designs. Due to cost advantages and improved environmental compatibility, gaseous fuels have recently become increasingly popular. Compared to injectors for liquid fuels, the injected gas volume occupies a much larger volume than an equivalent amount of liquid fuel. This results in an increased stroke requirement for a closing element, which is usually actuated by a magnetic actuator. Designing a magnetic circuit using standard materials is very difficult, or sometimes impossible, due to the limited installation space. Materials with higher magnetic force are very expensive and sometimes harmful to health (e.g., FeCo).A gas nozzle for a gas valve is already known from DE 10 2021 206 438 A1, which comprises a nozzle body that is at least partially hollow-cylindrical in shape and forms a sealing seat over which a gas flow path leads. Furthermore, the gas valve has a valve-closing element that is partially accommodated in the nozzle body and has an end section that is arranged outside the nozzle body and has a sealing contour that interacts with the sealing seat. Furthermore, the gas valve has a sleeve that surrounds the nozzle body and the end section of the valve-closing element and delimits the gas flow path downstream of the sealing seat. The gas flow path downstream of the sealing seat has a cross-sectional constriction to achieve the Venturi effect, in the region of which at least one intake channel opens. The sleeve is designed in the form of a blow cap that can be applied to the nozzle body.

[0006] Another injector for injecting a gaseous medium is also known from WO 2023 / 001384 A1. The blow cap, which can be placed on a nozzle body, comprises a sleeve-shaped base body with a circumferential surface that merges into a base region at the downstream end. The base region is designed such that at least one obliquely or asymmetrically discharging outlet opening is provided. Furthermore, a flow guide section directed inward toward the valve closing element, counter to the flow direction, is formed in the base region, which deflects the gas to be discharged.

[0007] Disclosure of the invention

[0008] The injector according to the invention for injecting a gaseous medium, in particular a gaseous fuel, into a combustion chamber of an internal combustion engine, with the features of claim 1, has the advantage that an optimized gas flow in the injector is made possible by the geometric design of a flow-influencing geometry arranged downstream of the sealing seat, so that the internal flow of the gaseous medium is designed to be as loss-free as possible via the inner contour of the cap-shaped attachment body, so that the back pressure located below, i.e. downstream of the valve closing element, is reduced and at the same time the jet can be introduced into the combustion chamber in a targeted manner.

[0009] In addition, the forces acting on the valve closing element are reduced to a minimum in a special way. This reduces the magnetic force of an actuator that must be selected to keep the injector open, thus enabling the use of cost-effective materials in the actuator's magnetic circuit.

[0010] This is achieved according to the invention in that the injector has a valve closing element for opening and closing at least one opening at a sealing seat. The valve closing element is preferably an axially movable valve needle with a plate-shaped end section. Furthermore, an actuator is provided for actuating the valve closing element. The actuator is preferably a magnetic actuator, but can also be, for example, a mechanically or (piezo-)electrically operated actuator. Further preferably, the actuator is configured to actively open the valve closing element by means of a lifting movement and to keep it open, while the valve closing element is closed by a spring force.

[0011] The flow influencing geometry, which is accommodated in particular in a cap-shaped attachment body, in short a blow cap, is characterized according to the invention in that the following relationship applies at maximum needle stroke lh of the valve closing element: 5 x lh > s > 1.5 x lh, where s is the distance between the radially outer contour of the valve closing element at its downstream edge region and the ring line lying axially below it in a projection on a section of the flow influencing geometry which tapers in the direction of flow, in order to generate a virtually loss-free flow downstream of the valve closing element.

[0012] The subclaims describe preferred developments of the invention.

[0013] It is particularly advantageous that the section of the flow-influencing geometry that tapers in the direction of flow downstream of the valve closing element is largely conical. It is advantageous that the angle of inclination a of the inner contour in the region of the tapered section is 85° > a > 30°, preferably > 45°.

[0014] These geometric specifications advantageously result in a strong flow redirection over a short axial distance in the region of the valve closing element, from a large diameter in the region of the sealing seat to a significantly smaller diameter along the tapered section of the inner contour, so that in this region immediately downstream of the valve closing element, flow is advantageously directed in the form of an “S-shaped beat”.

[0015] This inner contour defined according to the invention, with its special features in shape and design, can be advantageously accommodated in attachment bodies with reducible external dimensions. This, in turn, enables very flexible use of sleeves or attachment bodies on injectors in various combustion chamber geometries of internal combustion engines. The present invention is preferably used in injection systems that inject directly into a combustion chamber. In particular, the injector is suitable for directly injecting hydrogen into the combustion chamber of an internal combustion engine.

[0016] drawing

[0017] Preferred embodiments of the invention are described in detail below with reference to the accompanying drawings. In the drawing:

[0018] Figure 1 is a schematic sectional view of an injector for injecting a gaseous medium according to the prior art,

[0019] Figure 2 is a sectional view of a known cap-shaped attachment body for an injector according to Figure 1,

[0020] Figure 3 is a schematic sectional view of a cap-shaped attachment body for an injector for injecting a gaseous medium according to a first embodiment,

[0021] Figure 4 is a schematic sectional view of a cap-shaped attachment body for an injector for injecting a gaseous medium according to a second embodiment,

[0022] Figure 5 is a schematic sectional view of a cap-shaped attachment body for an injector for injecting a gaseous medium according to a third embodiment, Figure 6 is a schematic sectional view of a cap-shaped attachment body for an injector for injecting a gaseous medium according to a fourth embodiment,

[0023] Figure 7 is a schematic sectional view of a cap-shaped attachment body for an injector for injecting a gaseous medium according to a fifth embodiment,

[0024] Figure 8 is a schematic sectional view of a cap-shaped attachment body for an injector for injecting a gaseous medium according to a sixth embodiment and

[0025] Figure 9 is a schematic sectional view of a cap-shaped attachment body for an injector for injecting a gaseous medium according to a seventh embodiment.

[0026] Preferred embodiments of the invention

[0027] For a better understanding of the invention, the basic structure of an injector for injecting a gaseous medium as well as a known structure of a flow-influencing geometry arranged downstream of the valve seat in terms of flow technology are described below with reference to Figures 1 and 2.

[0028] Figure 1 shows a schematic cross-sectional view of the known injector 1 for injecting a gaseous medium. Since the invention is directed to the flow-influencing geometry 10, which is arranged downstream of the valve seat 3 in terms of flow technology, only this assembly will be described in more detail here for the known injector 1. A magnetic actuator 21, for example, is provided to actuate the injector 1, so that the injector 1 can be controlled in a targeted manner.

[0029] The injector 1 also has a nozzle body 2, which on the injection side forms a conically shaped valve seat 3 at its end for a valve closing element 5 that opens outwards, i.e., opens towards a combustion chamber 20. The valve closing element 5 is guided axially movably within the nozzle body 2 via a guide 18. In addition, the valve closing element 5 has an end section 6 in the form of a valve disk, which forms a sealing seat 7 corresponding to the valve seat 3. The two sealing seat partners, valve seat 3 and valve closing element 5, are each made of metal. The geometric and material design is such that sufficient tightness is guaranteed during operation of a hydrogen engine.In the event of a fault, a shut-off system (not shown here) installed upstream of the injector 1 for safety reasons would interrupt the supply of the gaseous medium, particularly the highly volatile hydrogen. The sealing contour of the end section 6 of the valve closing element 5 is, for example, rounded, while the valve seat 3 on the nozzle body 2 has a conical shape. However, other contours are also conceivable.

[0030] The nozzle body 2 and the end section 6 of the valve closing element 5 are surrounded by a sleeve 8 for jet shaping. In the following, and in particular with reference to the invention, reference is generally made to a flow-influencing geometry 10 arranged downstream of the sealing seat 7 in terms of flow technology. This can either be formed directly as a single piece on the nozzle body 2, which, however, requires a high manufacturing outlay, or it can be integrated into an additional component, which, with reference to the prior art embodiments in Figures 1 and 2, is generally referred to as a sleeve 8. The sleeve 8 has a large overlap length with the nozzle body 2 in order to be able to fasten the sleeve 8 securely and reliably. In principle, however, reference can also be made to a cap-shaped attachment body 8, which, with reference to the exemplary embodiments according to the invention, is also defined as a blow cap 8.

[0031] The sleeve 8 and the end section 6 of the valve closure element 5 jointly define a gas flow path 4, into which at least one intake channel 15 formed in the sleeve 8 opens. Air from the environment can be drawn into the gas flow path 4 via the one or more intake channels 15.

[0032] If the valve closing element 5 is in an open position lifted from the valve seat 3, the gas flow path 4 then leads via the valve seat 3 into an interior of the sleeve 8, which is characterized by a special shape with an inner contour 9. Starting from a cylindrical section 11 of the sleeve 8 and following the valve closing element 5 in the direction of flow, a cross-sectional reduction occurs at a large axial distance from the valve closing element 5 in a central cylindrical axial region 13 of the flow-influencing geometry 10 of the sleeve 8, with the taper being achieved via a conically running section 12 in the inner contour 9 of the sleeve 8. The intake channels 15 open into the inner contour 9 of the sleeve 8 precisely in the central axial region 13.

[0033] The reduction in cross-section within the gas flow path 4 ensures that, as the gas flows out via the gas flow path 4 towards an outlet 19, air from the environment is sucked into the gas flow path 4 via the intake channels 15 (“Venturi effect”). This means that air is mixed with the gas before it reaches the outlet 19, thus improving mixture preparation. The reduction in cross-section is canceled out by the fact that the central axial region 13 is again followed by a conically running section 14, but in this case widening conically in the direction of flow, with this section 1 extending as far as the outlet 19. The reduction in cross-section in the inner contour 9 of the sleeve 8 is intended to achieve the Venturi effect, which is optimized together with the air admixture.

[0034] Experience has shown that with such a solution or with other known geometries or inner contours of cap-shaped attachment bodies, sufficiently good results are not achieved with regard to the introduction of the jets into the combustion chamber 20 or their jet guidance and jet shaping for optimal combustion.

[0035] Therefore, the object of the invention is to provide an inner contour 9 of a cap-shaped attachment body 8 with a flow-influencing geometry 10 arranged downstream of the sealing seat 7, with which optimal combustion results are achieved due to the flow guidance according to the invention.

[0036] Injection systems for the direct injection of a gaseous medium, in particular hydrogen, but also CNG, methane, ammonia or mixtures of the aforementioned gases, have the task of specifically controlling the dosage as well as the injection direction of the gas jet(s) into the combustion chamber 20 via injection valves or, in general, injectors 1. For this purpose, corresponding sleeves or blow caps 8 can be used on the injector 1, as already explained above. Furthermore, injection systems for the (hydrogen)-

[0037] Direct injection, by its very nature, requires a large lift of the valve needle with the valve closing element 5. Designing a magnetic circuit (magnetic actuator 21) using standard materials is very difficult, or in some cases impossible, due to the limited installation space. Materials with higher magnetic force and thus better B / H characteristics are very expensive and sometimes even harmful to health (e.g., FeCo). Therefore, a reduction in magnetic force should also be achieved through improved jet guidance.

[0038] The core of the invention is to design the internal flow of the gaseous medium with as little loss as possible via the inventive inner contour 9 of the cap-shaped attachment body 8, so that the back pressure located below, i.e., downstream of the plate-shaped end section 6 of the valve closing element 5 is reduced and, at the same time, the jet can be introduced into the combustion chamber 20 in a targeted manner. This defined inner contour 9, with its special features in shape and design, can advantageously be accommodated in attachment bodies 8 with reducible external dimensions. This, in turn, enables a very flexible use of sleeves or attachment bodies 8 on injectors 1 in various combustion chamber geometries of internal combustion engines.

[0039] In the following, injectors 1 with flow-influencing geometries 10 according to the invention, which are arranged downstream of the valve seat 3 in terms of flow technology, are described in detail with reference to Figures 3 to 9, according to preferred exemplary embodiments of the invention. As already mentioned, these flow-influencing geometries 10 can be formed directly as one piece on the nozzle body 2 or, as shown in all figures, integrated into an additional component which can be referred to as a cap-shaped attachment body 8 (in short, blow cap 8). The attachment body 8 will usually have a significantly smaller overlap length with the nozzle body 2 than shown in Figure 1. The only essential factor is a secure and reliable attachment to the nozzle body 2, which enables perfect and axially parallel alignment with the injector 1. Known joining methods such as pressing, welding, soldering, gluing or combinations thereof can be used.Figure 3 shows a first embodiment of a flow-influencing geometry 10 arranged downstream of the valve seat 3 in a cap-shaped attachment body 8 and created via an internal contour 9 according to the invention. The valve closing element 5 with its plate-shaped end section 6 is shown only schematically and in a simplified manner. However, the end section 6 can also have chamfers or rounded portions on its outer contour.

[0040] The flow influencing geometry 10 produced with the inner contour 9 according to the invention has several essential aspects and geometric specifications, the ratio of two surfaces to one another being considered as the essential criterion of the invention. To be precise, the two surfaces As and Ai are considered, which result at maximum valve needle lift lh, i.e. with the sealing seat 7 maximally open and thus the valve closing element 5 maximally lifted. The surface As represents the annular seat cross-sectional area that results between the valve seat 3 and the contact line of the end section 6 of the valve closing element 5, while the surface Ai is determined by the distance that results from the shortest distance between the outer contour of the valve closing element 5 at its downstream edge region and the opposite wall of the inner contour 9.In other words, the area Ai represents the narrowest cross-section below the valve closing element 5 when the sealing seat 7 is fully open. This area Ai is also annular and, as an imaginary surface, here at an approximately right angle, is located on a tapered, in particular conically running section 12 in the inner contour 9 of the attachment body 8, which ensures a significant taper of the inner contour 9 over a short axial extent, which also advantageously contributes to the desired optimized flow result. According to the invention, the ratio of the areas As and Ai should be: Ai > 2.5 x As. The jet guidance coming from the sealing seat 7 takes place via the inner contour 9 in the conically running section 12, which is designed with an inclination angle a of 60° > a > 30°, preferably with an inclination angle a of > 45°.With this relatively large angle a of the conical section 12, a strong radially inward flow component is generated over a very short axial length. The lines of flow path 4 illustrate this.

[0041] A further characteristic of the design of the inner contour 9 is the distance s which results at maximum needle lift lh between the radially outer contour of the valve closing element 5 at its downstream edge region and the ring line lying axially below it in a projection on the conical section 12. The following should apply: 5 x lh > s > 1.5 x lh in order to generate a virtually loss-free flow around the end section 6 of the valve closing element 5. In particular, for an optimized flow result, 4 x lh > s > 2.5 x lh applies. The maximum needle lift lh extends over an axial extension length of 100 pm to 2 mm, whereby the maximum needle lift lh will ideally be between 0.15 mm and 0.5 mm.

[0042] As a result of these geometric specifications, a flow redirection takes place over a short axial distance in the area of ​​the valve closing element 5 from a large diameter in the area of ​​the sealing seat 7 to a significantly smaller diameter with an inner surface A2 at the end of the tapered, in particular conical, section 12, so that in this area immediately downstream of the valve closing element 5, flow deflection advantageously takes place in the form of an "S-bend". Instead of the conical shape of section 12, this section 12 can also have a slightly convex or slightly concave curvature. In addition to the ratio of the flow cross sections corresponding to Ai > 2.5 x As, the following should therefore also apply to the flow cross sections of the areas As and A2: 5 x As > A2 > 2 x As, so that a supercritical flow is ensured and a limitation of back pressures below the valve closing element 5 is achieved.

[0043] This is also associated with the acceleration of the flow into the actual outlet bore, which is characterized by the axial region 13 following the conical section 12 in the flow direction, with a reduction in losses or turbulence in the wall region and an approximation of the effective flow cross-section to the geometric cross-sectional area A2. These measures allow a lowering of the outlet areas of the inner bore defined by the inner contour 9 in the region of the outlet 19 without influencing the back pressure below the valve closing element 5. In the present embodiment according to Figure 3, the diameters of the inner flow path d2 at the inlet into the axial region 13 and d2 at the outlet from the axial region 13 in the region of the outlet 19 are largely selected to be the same size, so that a largely cylindrical outlet bore with the axial region 13 is present.

[0044] Reducing the diameters da of the outlet bores in the area of ​​the axial sections 13 toward the outlet 19 increases the ratio of hole length L, i.e., the axial length of the axial section 13, to the outlet diameter da, thereby increasing jet stability and, above all, jet velocities. The following relationships should apply to the aforementioned parameters: L / da > 0.2; L / ds > 0.2; ideally, however, L / da > 1.

[0045] Figures 4 to 9 show six further exemplary embodiments of flow-influencing geometries 10 arranged fluidically downstream of the valve seat 3 in a cap-shaped attachment body 8 and generated via an internal contour 9 according to the invention. In particular, modifications in the area of ​​sections 12 and 13 of the cap-shaped attachment body 8 are proposed, which achieve the advantageous effects described above.

[0046] Figure 4 shows a solution in which a hole taper is present in the axial region 13 of the inner contour 9. The angle k for the hole taper is 20° > k > 2°. Depending on the hole length L, the diameter da can be reduced by 5% to 50% compared to the diameter da.

[0047] Figure 5 shows a cap-shaped attachment body 8 in which a very large angle of inclination a has been selected in the conical section 12, whereby the angle a can be up to 85°, for example. The following applies here as well: 5 x lh > s > 1.5 x lh, in order to generate a virtually loss-free flow around the end section 6 of the valve closing element 5. By using a large angle a of the conical section 12, the relationship can shift in the direction of 3 x lh > s > 1.5 x lh. The axial region 13 of the inner contour 9 can be cylindrical or conical.

[0048] Figures 6 and 7 show two embodiments in which the outlet bore is further subdivided in the axial region 13. In the embodiment shown in Figure 6, the initially cylindrical axial region 13 abruptly transitions into an end region 13a with a spherical bulge. The spherical bulge, which is convex when viewed from the inside, ensures the application of the flow, which may be desired for certain installation conditions and combustion chamber structures. The radius R of the spherical bulge in the end region 13a does not necessarily have to be constant.

[0049] In the design according to Figure 7, the initially conical axial area

[0050] 13 transitions at a kink into an end region 13b, which is also conical, but has a smaller angle k than the angle k of the axial region 13. The conical axial region 13 can also, as shown, transition into a cylindrical end region 13b. For the surfaces A2 and A3 in the area of ​​diameters d2 and d a, the following applies: 0.8 x A2 > A3 > 0.5 x A2.

[0051] In the embodiment shown in Figure 8, a subdivision of the outlet bore is also provided in the region of the axial region 13. In this embodiment shown in Figure 8, the initially cylindrical axial region 13 transitions with a bend into a conically extending end region 13c that tapers in the direction of flow. The relationships between the surfaces A2 and A3 can also apply here, as indicated for Figures 6 and 7.

[0052] Figure 9 shows a cap-shaped attachment body 8 which has a modified valve closing element 5, the end section 6 of which has an additional flow former 22 which, in contrast to the actual plate-shaped shape, has a downstream-directed contour. The flow former 22 can, for example, be a needle tip shaped conically or cylindrically in the center of the valve closing element 5. For the design of the flow former 22 to be cylindrical or conical, the following relationships should apply with regard to the diameter d2 at the inlet to the axial region 13: 2 / 3 x da > b > 1 / 3 x da (cylindrical); 2 / 3 x da > bi; ba > 1 / 3 x da (conical). The illustrated embodiment shows a flow former 22 whose diameter bi, starting at the end section 6 of the valve closing element 5, corresponds to the diameter of the shaft of the valve needle upstream of the end section 6. However, this is only one possible design variant.Rather, the diameter bi can also be larger or smaller than the diameter of the valve needle shaft. The flow shaper 22 can, for example, also extend in the downstream direction starting from the radially outer contour of the end section 6 of the valve closure element 5.

[0053] In general, the flow former 22 can be described in such a way that on the downstream underside of the end section 6 of the valve closing element 5, an additional axial component in the downstream direction is provided which deviates from the largely plate-shaped design and thus forms part of the flow influencing geometry 10.

[0054] The design variants of the exemplary embodiments according to Figures 3 to 8 with respect to the inner contour 9 of the outlet bore with the axial region 13 can be combined at any time with the design of the valve closing element 5 with flow former 22 according to Figure 9. The axial length of the flow former 22 should be smaller than the distance of the valve plate to the inlet into the axial region 13 when the sealing seat 7 is fully open and thus the valve needle lift lh is at its maximum.

[0055] The flow shaper 22 on the downstream underside of the valve closure element 5 enables the flow stabilization of the internal flow immediately downstream of the valve disk and reduces the forces acting there. The influences on the valve needle's stiffness are limited by the corresponding dimensions of the flow shaper 22 outlined above.

[0056] Furthermore, the proposed solutions achieve more flexible hole designs, which may be necessary, for example, where installation space is limited. This offers increased degrees of freedom for various dimensions of cap-shaped attachment bodies 8, with the outer diameters of the attachment bodies 8 in the area of ​​attachment to the nozzle body 2 being, for example, in the range from 8 mm to 15 mm, while the outer diameters of the attachment bodies 8 in the area of ​​the outlet 19 are, for example, in the range from 6 mm to 12 mm. The designs can generally be supplemented or combined in various sub-variants using radii R in the form of rounded sections (see, for example, Figure 5) instead of angular and sharp-edged transitions.

Claims

Claims 1. Injector (1) for injecting a gaseous medium, in particular a gaseous fuel, preferably hydrogen, into a combustion chamber (20) of an internal combustion engine, comprising an axially movable valve closing element (5) for opening and closing at least one opening on a sealing seat (7), an actuator (21) for actuating the valve closing element (5), and a flow-influencing geometry (10) arranged downstream of the sealing seat (7) in terms of flow technology, characterized in that at maximum needle lift (lh) of the valve closing element (5), the following relationship applies: 5 x lh > s > 1.5 x lh, where (s) is the distance between the radially outer contour of the valve closing element (5) at its downstream edge region and the annular line lying axially below it in a projection on a section (12) of the flow-influencing geometry (10) tapering in the flow direction,to generate a virtually loss-free flow downstream of the valve closing element (5).

2. Injector according to claim 1, characterized in that the ratio is preferably 4 x lh > s > 2.5 x lh.

3. Injector according to claim 1 or 2, characterized in that at maximum valve needle lift (lh) an annular seat cross-sectional area (As) is produced between a valve seat (3) and the contact line of the valve closing element (5) and a further annular area (Ai) is determined by the distance which is the shortest distance between the outer contour of the valve closing element (5) at its downstream end and the opposite wall of the section (12) of the flow influencing geometry (10) tapering in the direction of flow, whereby the ratio of the areas (As and Ai) is: Ai > 2.5 x As.

4. Injector according to claim 3, characterized in that at the end of the section (12) tapering in the direction of flow there is an outlet bore with at least one axial region (13) and thus the entire inner contour (9) of the flow influencing geometry (10) is defined up to an outlet (19), wherein at the beginning of the axial region (13) an inner surface (A2) is defined and in relation to the annular seat cross-sectional area (As) the following applies: 5 x Aces > A2 > 2 x Aces.

5. Injector according to claim 4, characterized in that the outlet bore has an axial region (13) divided into several subsections.

6. Injector according to claim 4 or 5, characterized in that the axial region (13) of the outlet bore following the section (12) tapering in the direction of flow is either cylindrical or also tapering.

7. Injector according to one of claims 4 to 6, characterized in that the outlet bore has a downstream end region (13a, 13b, 13c) leading towards the outlet (19), which is either cylindrical or conically tapered or spherically curved.

8. Injector according to one of claims 4 to 7, characterized in that the diameter (da) of the axial region (13) of the outlet bore in the region of the outlet (19) is less than or equal to the diameter W2) at the beginning of the axial region (13).

9. Injector according to one of the preceding claims, characterized in that the section (12) of the flow-influencing geometry (10) tapering in the flow direction is largely conical downstream of the valve closing element (5).

10. Injector according to one of the preceding claims, characterized in that the section (12) of the flow-influencing geometry (10) tapering in the flow direction downstream of the valve closing element (5) is designed with an inclination angle a of 85° > a > 30°, preferably with an inclination angle a of > 45°.

11. Injector according to one of the preceding claims, characterized in that the flow-influencing geometry (10) arranged downstream of the sealing seat (7) is realized in a cap-shaped attachment body (8), in particular a blow cap.

12. Injector according to claim 11, characterized in that the cap-shaped attachment body (8) can be attached to a spray-side end of the injector (1), in particular to a nozzle body (2).

13. Injector according to one of the preceding claims, characterized in that the valve closing element (5) is part of an axially movable valve needle, wherein the valve closing element (5) has an end section (6) which is largely plate-shaped. 1 . Injector according to claim 13, characterized in that a flow former (22) is formed on the downstream underside of the end section (6) of the valve closing element (5), which flow former gives the largely plate-shaped design an additional axial component in the downstream direction, which is thus part of the flow influencing geometry (10).

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