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 on a sealing seat (7), an actuator (21) for actuating the valve closing element (5), and a flow-control geometry (10) located downstream of the sealing seat (7).According to the invention, the flow control geometry (10) is designed such that it is formed downstream of the sealing seat (7) in an attachment body (8), wherein the attachment body (8) has a hollow cylindrical section in the area of ​​the sealing seat (7), to which an outflow area (16) with at least one outflow opening (17) having an inner contour (9) is connected, which opens into an end side (25) facing the combustion chamber (20), wherein in the transition from the hollow cylindrical section to the at least one outflow opening (17) the inner contour (9) has a trough-like section (22), from which at least one additional opening (24) is connected with the outer contour of the attachment body (8) in order to improve a scavenging behavior from the outflow opening (17).

Description

State of the art

[0001] The present invention relates to an injector for injecting a gaseous medium, in particular a gaseous fuel, into a 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.

[0002] Gas injectors are known in various designs from the prior art. Due to cost advantages and improved environmental compatibility, gaseous fuels have become increasingly popular recently. A problem compared to injectors for liquid fuels is that the injected quantity of gas occupies a much larger volume than an equivalent quantity of liquid fuel. This results in an increased stroke requirement for a closing element, which is usually actuated by a magnetic actuator. Designing the magnetic circuit with standard materials is very difficult or sometimes impossible due to the limited installation space. Materials with higher magnetic strength are very expensive and some are hazardous to health (e.g., FeCo).

[0003] From DE 10 2021 206 438 A1, a gas nozzle for a gas valve is already known, comprising a nozzle body that is at least partially hollow and cylindrical, forming a sealing seat over which a gas flow path leads. The gas valve also has a movable valve closing element, partially integrated into the nozzle body, with an end section located outside the nozzle body and having a sealing contour that interacts with the sealing seat. Furthermore, the gas valve has a sleeve surrounding the nozzle body and the end section of the valve closing element, which limits 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-off cap that can be attached to the nozzle body.

[0004] Another injector for injecting a gaseous medium is also known from WO 2023 / 001384 A1. The blowing cap, which can be mounted on a nozzle body, has a sleeve-shaped base with a circumferential outer surface that transitions into a bottom section at the downstream end. The bottom section is designed such that at least one obliquely or asymmetrically blowing outlet opening is provided, and furthermore, the bottom section incorporates a flow-guiding section directed inwards towards the valve closing element, opposite to the flow direction, which deflects the flow of the gas to be blown out. Disclosure of the invention

[0005] 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 enabled by the geometric design of a flow control geometry downstream of the sealing seat, so that the internal flow of the gaseous medium is designed with as little loss 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.

[0006] Furthermore, 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.

[0007] According to the invention, this is achieved by the injector having 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 disc-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. Preferably, the actuator is configured to actively open and hold the valve closing element open by means of a stroke movement, while the valve closing element is closed by a spring force.

[0008] The flow control geometry, which is housed in particular in a cap-shaped attachment body, or in short, a blow cap, is characterized according to the invention in that the attachment body has a hollow cylindrical section in the area of ​​the sealing seat, to which an outflow area with at least one outflow opening having an inner contour is connected, which opens in an end side facing the combustion chamber, wherein in the transition from the hollow cylindrical section to the at least one outflow opening the inner contour has a trough-like section, from which at least one additional opening is connected with the outer contour of the attachment body.

[0009] In this way, mixture formation and the purging behavior of remaining residual gas, especially hydrogen, from the exhaust port are improved. This effectively prevents spontaneous and premature pre-ignition of the hydrogen, as the hydrogen concentration in the fuel / air mixture is diluted by the drawn-in combustion chamber gases.

[0010] The dependent claims describe preferred embodiments of the invention.

[0011] The flow control geometry according to the invention is integrated into a relatively open mounting structure following the sealing seat. Such attachment bodies have the advantages of a very simple design and simple, easily reproducible manufacturing. Furthermore, no blocked dead volume is created inside the attachment body, which could adversely lead to premature pre-ignition.

[0012] The concept according to the invention allows for particularly high flexibility in the design of the spray pattern. The gas flow can be distributed very evenly throughout the entire combustion chamber, which improves mixture formation and increases efficiency.

[0013] It is particularly advantageous to provide between two and eight additional openings, ideally arranged evenly distributed around the circumference. These additional openings are inclined at an angle to the central axis of the injector, with the angle of inclination preferably being between 25° and 60°.

[0014] The outer contour of the attachment body is formed by a radially outer shell side and the end side facing the combustion chamber, with the additional openings advantageously connecting the shell side with the trough-like section of the inner contour.

[0015] The injector is inserted into a receiving bore of a cylinder head, with the attachment body of the injector preferably projecting into the combustion chamber in such a way that the additional openings on the outer contour of the attachment body, particularly on the outer surface, are freely accessible to the combustion chamber gas. Alternatively, an installation situation in which the additional openings are partially or completely covered by the inner wall of the receiving bore of the cylinder head may also be advantageous.

[0016] The highly variable internal contour allows for very flexible use of sleeves or attachment bodies on injectors in various combustion chamber geometries of internal combustion engines.

[0017] The present invention is preferably used in injection systems that inject hydrogen directly into a combustion chamber. In particular, the injector is suitable for the direct injection of hydrogen into a combustion chamber of an internal combustion engine. drawing

[0018] Preferred embodiments of the invention are described in detail below with reference to the accompanying drawing. The drawing shows: Fig. 1 A schematic sectional view of an injector for injecting a gaseous medium according to the state of the art, Fig. 2 a sectional view of a known cap-shaped attachment body for an injector according to Fig. 1, Fig. 3 A schematic sectional view of a cap-shaped attachment body for an injector for injecting a gaseous medium according to a first embodiment in an open sealing seat state and in several symbolically indicated installation situations in a cylinder head, Fig. 4 a schematic sectional view of a cap-shaped attachment body for an injector for injecting a gaseous medium according to a second embodiment in an open sealing seat state, Fig. 5 a detailed view according to section V in Fig. 4 to illustrate a conical additional opening serving to improve rinsing, Fig. 6 a schematic sectional view of a cap-shaped attachment body for an injector for injecting a gaseous medium according to the first embodiment in a closed sealing seat condition and Fig. 7 a schematic sectional view of a cap-shaped attachment body for an injector for injecting a gaseous medium according to the second embodiment in a closed sealing seat state. Preferred embodiments of the invention

[0019] To better understand the invention, the following will be explained using the Fig. 1 and Fig. 2 the basic structure of an injector for injecting a gaseous medium and a known structure of a flow control geometry downstream of the valve seat is described.

[0020] In the Fig. Figure 1 shows a schematic cross-sectional view of the known injector 1 for injecting a gaseous medium. Since the invention relates to the flow control geometry 10, which is downstream of the valve seat 3, only this assembly of the known injector 1 will be described in detail here. For actuating the injector 1, a magnetic actuator 21 is provided, for example, so that the injector 1 can be controlled in a targeted manner.

[0021] The injector 1 also has a nozzle body 2 which, on the injection side, forms a valve seat 3 at its end, for example, a conically shaped one, for an outwardly opening valve closing element 5, i.e., opening towards a combustion chamber 20. The valve closing element 5 is guided axially within the nozzle body 2 by a guide 18. Furthermore, the valve closing element 5 has an end section 6 in the form of a valve disc, which, corresponding to the valve seat 3, forms a sealing seat 7. Both sealing seat components, valve seat 3 and valve closing element 5, are made of metal. The geometric and material design is such that sufficient sealing is ensured during the operation of a hydrogen engine.In the event of a malfunction, a shut-off system (not shown here), installed upstream of 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.

[0022] 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 particularly with regard to the invention, a flow-control geometry 10 downstream of the sealing seat 7 is generally referred to. This can either be formed directly as a single component on the nozzle body 2, which, however, requires considerable manufacturing effort, or be integrated into an additional component, whereby this component, with reference to the embodiments according to the prior art, is described in the Fig. 1 and Fig. 2 is generally referred to as sleeve 8. The sleeve 8 has a large overlap length with the nozzle body 2 in order to securely and reliably attach the sleeve 8. However, it can also be described as a cap-shaped attachment body 8, which, in relation to the embodiments according to the invention, is also defined as a blow cap 8.

[0023] The sleeve 8 and the end section 6 of the valve closing element 5 together 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 one or more intake channels 15.

[0024] 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 flow direction of the valve closing element 5, a reduction in cross-section occurs at a large axial distance from the valve closing element 5 in a central cylindrical axial region 13 of the flow control geometry 10 of the sleeve 8, whereby the narrowing is achieved via a conically extending section 12 in the inner contour 9 of the sleeve 8. The intake channels 15 open precisely into the inner contour 9 of the sleeve 8 in the central axial region 13.

[0025] The reduction in cross-section within the gas flow path 4 creates the effect that, as the gas flows out through the gas flow path 4 towards an outlet 19, air from the surroundings is drawn into the gas flow path 4 via the intake channels 15 ("Venturi effect"). This means that air is mixed with the gas even before it reaches the outlet 19, thus improving the mixture preparation.

[0026] The reduction in cross-section is reversed by the fact that the central axial region 13 is followed by a conically extending section 14, in this case widening conically in the flow direction, with this section 14 extending to 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 in conjunction with the air mixture. Experience has shown that such a solution, or other known geometries or inner contours of cap-shaped attachments, does not achieve sufficiently good results with regard to the introduction of the jets into the combustion chamber 20, or their guidance and shaping for optimal combustion. Furthermore, there is a risk of engine pre-ignition due to insufficient purging, particularly of the hydrogen remaining in the attachment.

[0027] 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 downstream of the sealing seat 7, with which optimal combustion results are achieved due to the flow guidance according to the invention, wherein an improved purge behavior of hydrogen remaining in the attachment body 8 is to be achieved by means of an outer contouring of the attachment body 8 in conjunction with the flow-influencing geometry 10 defined by the inner contour 9 in order to avoid pre-ignition.

[0028] Injection systems for the direct injection of a gaseous medium, especially hydrogen, but also CNG, methane, ammonia, or mixtures of the aforementioned gases, have the task of precisely controlling the metering and the injection direction of the gas jet(s) into the combustion chamber 20 via injection valves or, more generally, injectors 1. For this purpose, corresponding sleeves or injection caps 8 can be used on the injector 1, as previously explained. Furthermore, injection systems for (hydrogen) direct injection inherently require a large stroke of the valve needle with the valve closing element 5. Designing the magnetic circuit (magnetic actuator 21) with known standard materials is very difficult or even impossible due to the limited installation space. Materials with higher magnetic force and thus better B / H characteristics are very expensive and, in some cases, also hazardous to health (e.g., FeCo).Therefore, improved beam guidance should also be used to achieve a reduction in magnetic force.

[0029] The core of the invention lies in shaping the internal flow of the gaseous medium with minimal loss 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 disc-shaped end section 6 of the valve closing element 5, is reduced and, at the same time, the jet can be directed precisely into the combustion chamber 20. This defined inner contour 9 is particularly aimed at improving mixture formation. Due to the highly variable contouring of the inner contour 9, a very flexible use of sleeves or attachment bodies 8 on injectors 1 in various combustion chamber geometries of internal combustion engines is enabled.

[0030] In particular, in combination with an inner contour 9 ending in at least one outflow opening 17, which also has a trough-like section 22 arranged upstream of the valve closing element 5 and thus directly downstream of the valve closing element 5, at least one additional opening 24, which is connected to the outer contour of the attachment body 8, can significantly improve the flushing behavior from the outflow opening 17.

[0031] Overall, the optimized jet-shaping cap and needle geometry allows for improved charge movement with increased purging of residual gas and hydrogen in the internal volume of the attachment body 8. This results in a robustness measure against pre-ignition even with increased seat leakage for the hydrogen injector during engine operation.

[0032] The following are, with reference to the Fig. 3 to 7 injectors 1 with flow-influencing geometries 10 according to the invention, which are downstream of the valve seat 3, are described in detail according to preferred embodiments of the invention. As already mentioned, these flow-influencing geometries 10 can be formed directly as a single component 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 (or simply blow cap 8). The attachment body 8 will typically have a significantly shorter overlap length with the nozzle body 2 than in Fig. Figure 1 shows the essential requirement. The only crucial factor is a secure and reliable attachment to the nozzle body 2, enabling perfect and axially parallel alignment with the injector 1. Common joining methods such as pressing, welding, soldering, gluing, or combinations thereof can be used.

[0033] In the Fig. Figure 3 shows a first embodiment of a flow-control geometry 10 located downstream of the valve seat 3 in a cap-shaped attachment body 8 and generated via an inner contour 9. The valve closing element 5 with its disc-shaped end section 6 is shown schematically and in a highly simplified cross-section as a chamfered rectangle. However, the end section 6 can also have further chamfers or rounded edges on its outer contour or be completely rectangular.

[0034] Fig. Figure 3 shows the first embodiment in an open sealing seat state and in several symbolically indicated installation situations in a cylinder head 23. The injector 1 is inserted into a largely cylindrical receiving bore 28 of the cylinder head 23.

[0035] The injection-side end with the flow-influencing geometry 10 of the injector 1 is arranged facing the combustion chamber 20 of the internal combustion engine. The flow-influencing geometry 10, generated by the internal contour 9 according to the invention and the at least one additional opening 24, has a key geometric characteristic that primarily deflects the gas flow radially inwards in a downstream direction within the attachment body 8, in order to then discharge the gas to be blown out, in particular hydrogen, into the at least one outlet opening 17. It should be expressly emphasized here that more than one outlet opening 17 can also be provided. However, the measures according to the invention are particularly effective when, as shown in the exemplary embodiments, only a single outlet opening 17 is provided. In the case of the examples shown in all figures, the outlet opening 17 is cylindrically shaped and parallel to the axis.

[0036] This optimized flow guidance is intended, above all, to significantly improve the flushing behavior from the outflow opening 17 in interaction with the at least one additional opening 24 introduced in the attachment body 8, which is connected to the outer contour of the attachment body 8.

[0037] For all described and shown embodiments according to Fig. 3 to 7, it is generally agreed that the flow control geometry 10 is formed downstream of the sealing seat 7 in an attachment body 8, wherein the attachment body 8 has a hollow cylindrical section in the area of ​​the sealing seat 7, to which an outflow area 16 with at least one outflow opening 17 having the inner contour 9 is connected, which opens into an end side 25 facing the combustion chamber 20, wherein in the transition from the hollow cylindrical section to the at least one outflow opening 17 the inner contour 9 has a trough-like section 22.

[0038] The thin-walled sleeve contour of the overlap area for attachment to the nozzle body 2 initially continues largely in the downstream direction, although variations in wall thickness along the axial length of the attachment body 8 are conceivable. In the axially subsequent outflow area 16, a significantly greater wall thickness is provided, depending on the number of outflow openings 17.

[0039] The flow control geometry 10 generated by the inner contour 9 has several essential aspects and geometric specifications. Downstream of the valve closing element 5, the inner contour 9 of the attachment body 8 is shaped such that the tapered, in particular conical, section 22 follows, which ensures a significant tapering of the inner contour 9 over a short axial extent, thus advantageously contributing to the desired optimized flow result. The jet guidance from the sealing seat 7 occurs via the inner contour 9 in the conical and overall trough-shaped section 22, which is designed with an inclination angle of 60° ≥ α ≥ 30°, preferably with an inclination angle of > 45°.With this relatively large angle of the conically shaped section 22, a strong radially inward flow component is generated over a very short axial length, so that in this region immediately downstream of the valve closing element 5, flow guidance advantageously occurs in the form of an "S-curve". Instead of the conical shape of section 22, this section 22 can also be slightly convex or slightly concave. The inner contour 9 ensures that a supercritical flow is maintained and that back pressures below the valve closing element 5 are limited.

[0040] The end face 25 of the attachment body 8 is understood to be its downstream end face, which is angled or slightly convex away from the outflow opening 17 and is directed towards the combustion chamber 20. In addition to the end face 25, the attachment body 8 has a circumferential shell 26, which forms the outer termination of the attachment body 8 and is inserted tightly or with clearance into the receiving bore 28 of the cylinder head 23.

[0041] Starting from the trough-shaped section 22 of the inner contour 9, at least one additional opening 24 extends to the outer contour of the attachment body 8, in particular to the outer shell side 26. Advantageously, two to eight additional openings 24 are provided, which are arranged, for example, evenly distributed around the circumference. The additional openings 24 pass through the wall of the outflow region 16 at an oblique angle. The angle of inclination α to the central axis of the injector 1 is preferably between 25° and 60°. In the outlet region of the additional openings 24 on the trough-shaped conical section 22 of the inner contour 9, an angle β of between 90° and 140° should be present due to the design of the attachment body 8 according to the invention. Advantageously, the diameters d a The following applies to the additional openings 24 in relation to the diameter D of the outflow opening 17: d a = 0.05...0.25 x D.

[0042] Theoretically, the additional openings 24 can also be arranged such that, with a small axial extension of the attachment body 8, they connect the end face 25 and the trough-like section 22. The additional openings 24 are cylindrical, with such a small diameter that a capillary effect can occur.

[0043] Preferably, the installation depth of the injector 1 in the receiving bore 28 of the cylinder head 23 is selected such that the attachment body 8 extends into the combustion chamber 20 and thus protrudes beyond the underside of the cylinder head 23 in the area of ​​a combustion chamber roof. The attachment body 8 extends sufficiently into the combustion chamber 20 that the additional openings 24 on the outer side 26 of the attachment body 8 are freely accessible to the combustion chamber gas. The dashed lines indicate two further alternative installation situations of the injector 1 in the cylinder head 23: one installation situation in which the additional openings 24 on the outer side 26 of the attachment body 8 are already partially in the receiving bore 28 of the cylinder head 23 and are thus partially covered, and another installation situation in which the additional openings 24 on the outer side 26 of the attachment body 8 are completely in the receiving bore 28 of the cylinder head 23 and are thus completely covered.In these two cases, the radial distance between the outer contour of the outer surface 26 of the attachment body 8 and the inner wall of the receiving bore 28 of the cylinder head 23 must be so large that at least via a capillary effect combustion chamber gas can still be drawn from the combustion chamber 20 into the additional openings 24 for purging residual gas from the interior of the attachment body 8 via the outflow opening 17.

[0044] Fig. Figure 4 shows a schematic sectional view of a cap-shaped attachment body 8 for an injector 1 for injecting a gaseous medium according to a second embodiment, also in an open sealing seat state. This differs from the example shown in Figure 4. Fig. 3 in particular by the fact that the additional openings 24 are conical. The additional openings 24 have their largest diameter in the region of the outer surface 26 of the attachment body 8, while their diameter is smallest at the opening into the trough-like section 22. Ideally, two to eight additional openings 24 are provided here as well. Solutions are also conceivable in which cylindrical and conical additional openings 24 are combined in one and the same attachment body 8.

[0045] Such attachment bodies 8 have the advantages of a very simple design and simple, easily reproducible manufacturing. Furthermore, no blocked dead volume is created inside the attachment body 8, which could disadvantageously lead to premature pre-ignition. The arrows 4 indicate the gas flow, the basic course of which is thus described when the sealing seat 7 is open.

[0046] Fig. 5 shows a detailed view according to section V in Fig. Figure 4 illustrates a conical additional opening 24 serving to improve rinsing. The conicity k of the conical additional opening 24 is, for example, in a range between 5° and 20°.

[0047] Fig. Figure 6 shows a schematic sectional view of a cap-shaped attachment body 8 for an injector 1 for injecting a gaseous medium according to the first embodiment in a closed sealing seat state, while Fig. Figure 7 shows a schematic sectional view of a cap-shaped attachment body 8 for an injector 1 for injecting a gaseous medium according to the second embodiment in a closed sealing seat state.

[0048] The number of additional openings is 24, as well as their diameter d. a on the side of the coat 26 or d iIn the area of ​​the trough-like section 22, the additional openings 24 are defined in a suitable area, as already described above, such that injection occurs only via the outlet opening 17 and that no outflows from the additional openings 24 can occur during the injection process, nor can any undesirable Coanda effects occur on the outer contour of the attachment body 8. Only after the injection process do the additional openings 24 allow the intake of fuel / combustion chamber gas / air mixture into the attachment body 8 with increased charge movement to enable improved purging. The arrows 40 in the additional openings 24, pointing in the opposite direction to the injection direction and extending to the inner contour 9 in the trough-like section 22, are intended to schematically illustrate this intake effect, with the purging flow 40 effectively and additionally preventing pre-ignition. The conicity k of the additional openings 24 further supports the desired effect, as smaller diameters d iare definable in the area of ​​the trough-like section 22.

[0049] The design features described above define an optimized attachment body 8 as a largely open blow cap. The advantages of the illustrated embodiments are that a targeted jet guidance downstream of the sealing seat 7 is achieved via the geometry of the inner contour 9 in conjunction with the additional openings 24, while simultaneously ensuring the purging of the gaseous medium, in particular hydrogen.

[0050] In addition to the optimized jet guidance made possible by the attachment body 8 according to the invention, further advantages of the attachment body 8 designed in this way are the increased strength and improved thermal conductivity. By avoiding back pressure downstream of the sealing seat 7, a high degree of pressure independence prevails in this area, so that optimized flushing from the attachment body 8 is possible at all times.

[0051] The concept according to the invention allows for particularly high flexibility in the design of the spray pattern. The gas flow can be distributed very evenly throughout the entire combustion chamber 20, which improves mixture formation and increases efficiency. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2021 206 438 A1

[0003] WO 2023 / 001384 A1

[0004]

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 releasing and closing at least one opening on a sealing seat (7), an actuator (21) for actuating the valve closing element (5), and a flow control geometry (10) downstream of the sealing seat (7) in terms of flow engineering characterized by , that the flow control geometry (10) is formed downstream of the sealing seat (7) in an attachment body (8), wherein the attachment body (8) has a hollow cylindrical section in the area of ​​the sealing seat (7), to which an outflow area (16) with at least one outflow opening (17) having an inner contour (9) is connected, which opens into an end side (25) facing the combustion chamber (20), wherein in the transition from the hollow cylindrical section to the at least one outflow opening (17) the inner contour (9) has a trough-like section (22), from which at least one additional opening (24) is connected with the outer contour of the attachment body (8) in order to improve a scavenging behavior from the outflow opening (17). [2] Injector according to claim 1, characterized by, that the outer contour of the attachment body (8) is formed by a radially outer shell side (26) and the end side (25) facing the combustion chamber (20), wherein the at least one additional opening (24) connects the shell side (26) with the trough-like section (22) of the inner contour (9). [3] Injector according to claim 1, characterized by , that the outer contour of the attachment body (8) is formed by a radially outer shell side (26) and the end side (25) facing the combustion chamber (20), wherein the at least one additional opening (24) connects the end side (25) with the trough-like section (22) of the inner contour (9). [4] Injector according to any of the preceding claims, characterized by , that the at least one additional opening (24) is inclined obliquely relative to the central axis of the injector (1), wherein the angle of inclination (α) to the central axis of the injector (1) is preferably between 25° and 60°. [5] Injector according to any of the preceding claims, characterized by , that in the mouth area of ​​the at least one additional opening (24) on the trough-like section (22) of the inner contour (9) an angle (β) is enclosed with this section (22) which is between 90° and 140°. [6] Injector according to any of the preceding claims, characterized by that the at least one additional opening (24) is either cylindrical or conical along its length, wherein in the case of a conical design the diameter (d a ) on the outer contour is larger than the diameter (d i ) at the tub-like section (22). [7] Injector according to any of the preceding claims, characterized by , that for the diameter (d a ) the at least one additional opening (24) on the outer contour in relation to the diameter (D) of the outflow opening (17) is given: d a = 0.05...0.25 x D. [8] Injector according to any of the preceding claims, characterized by, that between two and eight additional openings (24) are provided. [9] Injector according to claim 8, characterized by , that the additional openings (24) are arranged evenly distributed over the circumference of the attachment body (8). [10] Injector according to any of the preceding claims, characterized by , that the flow control geometry (10) which is downstream of the sealing seat (7) is realized in a blow cap (8). [11] Injector according to any of the preceding claims, characterized by , that the cap-shaped attachment body (8) can be attached to an injection-side end of the injector (1), in particular to a nozzle body (2). [12] Injector according to any of the preceding claims, characterized by , 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 disc-shaped. [13] Injector according to any of the preceding claims, characterized by , that this can be inserted into a receiving bore (28) of a cylinder head (23), wherein the attachment body (8) protrudes into the combustion chamber (20) in such a way that the at least one additional opening (24) on the outer contour of the attachment body (8) is either freely accessible to the combustion chamber gas or is partially or completely covered by the inner wall of the receiving bore (28) of the cylinder head (23).

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