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 way that it is formed in an attachment body (8) downstream of the sealing seat (7), wherein the attachment body (8) has a hollow cylindrical section in the region of the sealing seat (7), which hollow cylindrical section is adjoined by at least one sleeve section (22) which extends over a circumferential region of the attachment body (8), has an axial length (L, L1, L2) and has an inner contour (9), said sleeve section enabling the gas flow to be directed or guided.

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 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.

[0005] 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 amount of gas to be injected 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 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).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.

[0006] 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.

[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 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.

[0009] 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.

[0010] 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.

[0011] 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 at least one sleeve section extending over a circumferential area of ​​the attachment body and having an axial length with an inner contour is connected, which provides gas flow control or

[0012] -guiding is enabled. In this way, mixture formation is improved in particular.

[0013] The dependent claims describe preferred embodiments of the invention.

[0014] The flow control geometry according to the invention is integrated into a very open mounting structure following the sealing seat, without any bottom areas. Such open mounting bodies have the advantages of a very simple design and simple, easily reproducible manufacturing. Furthermore, no blocked dead volume is created inside the mounting body, which could adversely lead to premature pre-ignition.

[0015] 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.

[0016] It is particularly advantageous to provide at least one sleeve section on the attachment body that extends only in a partial circle around the circumference and allows for a radially inward flow direction. For this purpose, the at least one sleeve section can have an orientation that is inclined obliquely inwards or curved radially inwards.

[0017] The invention is characterized by a precisely designed flow contour of an open blow cap. In open blow caps, the incoming medium is guided stably from the sealing seat to introduce the injected medium, particularly hydrogen, into the combustion chamber with minimal loss of maximum flow velocity. This is achieved, firstly, by the directional angles of the guide surface (angle α) and corresponding radii on the sleeve sections, and secondly, by the length-to-diameter ratios of the blow cap geometry (L / D). The stability of the jet can also be precisely controlled via the circumferential angle (angle β) of the open blow cap. In addition to a single-sided jet guidance, a double-sided jet guidance behind the sealing seat is also possible. This allows for the realization of any desired jet shape with greater flexibility.

[0018] The highly variable internal contour allows for a very flexible use of sleeves or attachment bodies on injectors in various combustion chamber geometries of internal combustion engines.

[0019] 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.

[0020] drawing

[0021] Preferred embodiments of the invention are described in detail below with reference to the accompanying drawing. The drawing shows:

[0022] Figure 1 shows a schematic sectional view of an injector for injecting a gaseous medium according to the prior art.

[0023] Figure 2 is a sectional view of a known cap-shaped attachment body for an injector according to Figure 1, 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,

[0024] Figure 4 shows a schematic sectional view of a cap-shaped attachment body for an injector for injecting a gaseous medium according to a second embodiment.

[0025] Figure 5 shows a schematic sectional view of a cap-shaped attachment body for an injector for injecting a gaseous medium according to a third embodiment.

[0026] Figure 6 shows a schematic bottom view of the cap-shaped attachment body along arrows VI in Figure 5.

[0027] Figure 7 shows a schematic sectional view of a cap-shaped attachment body for an injector for injecting a gaseous medium according to a fourth embodiment.

[0028] Figure 8 shows a schematic sectional view of a cap-shaped attachment body for an injector for injecting a gaseous medium according to a fifth embodiment.

[0029] Figure 9 shows a perspective view of the cap-shaped attachment body for an injector for injecting a gaseous medium according to the fifth embodiment; Figure 10 shows a schematic sectional view of a cap-shaped attachment body for an injector for injecting a gaseous medium according to a sixth embodiment as a preferred embodiment of the fifth example.

[0030] Figure 11 shows an isometric view of the cap-shaped attachment body for an injector for injecting a gaseous medium according to the sixth embodiment and

[0031] Figure 12 shows a simplified underside view of the cap-shaped attachment body for an injector for injecting a gaseous medium according to the fifth or sixth embodiment.

[0032] Preferred embodiments of the invention

[0033] For a better understanding of the invention, the basic structure of an injector for injecting a gaseous medium and a known structure of a flow-technically downstream component of the valve seat are described below with reference to Figures 1 and 2.

[0034] Flow control geometry described.

[0035] 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-related arrangement downstream of the valve seat 3...

[0036] Since the flow control geometry 10 is directed, only this assembly of the known injector 1 will be described in more detail here. For example, a magnetic actuator 21 is provided for actuating the injector 1, allowing it to be controlled in a targeted manner. 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 tightness 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.

[0037] 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 piece on the nozzle body 2, which, however, requires considerable manufacturing effort, or be integrated into an additional component, which, with reference to the embodiments according to the prior art shown in Figures 1 and 2, is generally referred to as the sleeve 8. The sleeve 8 has a large overlap length with the nozzle body 2 in order to be able to securely and reliably fasten the sleeve 8. However, it can also be described as a cap-shaped attachment body 8, which, with reference to the embodiments according to the invention, is also defined as the blow cap 8.

[0038] 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.

[0039] 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.

[0040] 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, ambient air 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.

[0041] The reduction in cross-section is reversed by the fact that the central axial area 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 thus intended to achieve the Venturi effect, which is optimized together with the air mixture.

[0042] Experience has shown that such a solution, or other known geometries or internal contours of cap-shaped attachment bodies, does not achieve sufficiently good results with regard to the introduction of the jets into the combustion chamber 20 or their jet guidance and jet shaping for optimal combustion.

[0043] 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.

[0044] 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 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 the (hydrogen)-

[0045] Direct injection inherently requires 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 some are also hazardous to health (e.g., FeCo). Therefore, an improved jet guidance is also intended to reduce the magnetic force. The core of the invention consists of using the inventive inner contour 9 of the cap-shaped attachment body 8 to design the internal flow of the gaseous medium with as little loss as possible, so that the back pressure 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 specifically designed to improve mixture formation by deflecting the gas flow radially inwards in a downstream direction. 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.

[0046] The following section describes injectors 1 with flow-influencing geometries 10 according to the invention, which are downstream of the valve seat 3, in preferred embodiments of the invention, with reference to Figures 3 to 12. As mentioned previously, these flow-influencing geometries 10 can be formed directly as a single unit 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 with the nozzle body 2 than shown in Figure 1. The only essential requirement is a secure and reliable attachment to the nozzle body 2, enabling perfect and axially parallel alignment with the injector 1. Known joining methods such as pressing, welding, brazing, bonding, or combinations thereof can be used.

[0047] 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 by an inner contour 9 according to the invention. The valve closing element 5 with its disc-shaped end section 6 is shown schematically and in a highly simplified cross-section as a rectangle. However, the end section 6 can also have chamfers or rounded edges on its outer contour.

[0048] Figure 3 shows an injector 1 for injecting a gas, with its injection end installed in a receiving bore of a cylinder head 23 of an internal combustion engine, which is also only shown very schematically. The injection end with the flow-influencing geometry 10 of the injector 1 is arranged facing the combustion chamber 20 of the internal combustion engine. As can be seen in Figures 3 to 7, the flow-influencing geometry 10 of the injector 1, and thus the injection cap 8, projects beyond the upper boundary of the cylinder head 23, in particular into a part of the combustion chamber 20.

[0049] The flow-influencing geometry 10 generated by the internal contour 9 according to the invention has a key geometric characteristic that primarily generates a deflection of the gas flow radially inwards in the downstream direction. Ideally, this deflection occurs only over a partial circumference, thus enabling, in particular, targeted jet shaping in one or more directions that are not parallel to the injector's axis. In the extreme case, no radially inwards gas flow is generated, namely when the attachment body 8 is designed as a hollow cylinder with a constant internal contour 9 and a constant inner diameter. Overall, the attachment body 8 is designed as an open blow-off body, i.e.,The thin-walled sleeve contour of the overlapping area for attachment to the nozzle body 2 largely continues in the downstream direction, although variations in wall thickness along the axial length of the attachment body 8 are conceivable. Such open attachment bodies 8 have the advantages of a very simple design and simple, easily reproducible manufacturing. Furthermore, no sealed dead volume is created inside the attachment body 8, which could adversely lead to premature pre-ignition.

[0050] According to the invention, the inner contour 9 of the attachment body 8 is characterized by at least one sleeve section 22 extending over a circumferential region of the attachment body 8 and having an axial length L, which generates a gas flow guidance or direction, in particular radially inwards due to the orientation of the sleeve section 22. The length L of the sleeve section 22 is defined as the length from the underside of the end section 6 of the valve closing element 5 to the lower edge of the sleeve section 22 projecting into the combustion chamber 20. The attachment body 8 has a diameter D in the region of the valve closing element 5. Ideally, L / D should be 1 to 3.5. The wall thickness s of the sleeve section 22 is specifically s = (0.05 - 0.15) x L.

[0051] As already indicated, the sleeve section 22 of the attachment body 8 is not fully formed, but only extends over a partial region of its circumference. Advantageously, the sleeve section 22 shown in Figure 3, with length L, extends only over an angular range of, for example, 90° to 270°. Depending on the angular extent of the semicircular sleeve section 22, the gas flow 4 can be directed more or less focused in desired directions. The inclination angle α of the sleeve section 22, deviating radially inward from the axially parallel perpendicular, is 0° to 60°. As shown, the inclination angle α of the sleeve section 22 is preferably between 10° and 45°. On the side opposite the sleeve section 22, the gas flow 4 can exit axially parallel and, theoretically, collide deeper within the combustion chamber 20 with the gas flow 4 deflected by the sleeve section 22.If this is desired, the inclination angle a of the sleeve section 22 must be chosen to be correspondingly large.

[0052] In general terms, the flow control geometry 10 downstream of the sealing seat 7 results as an inner contour 9 shaped over the circumference, in which at least one sleeve section 22, in particular a semicircular one, with a length L is provided.

[0053] 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. This differs only slightly from the first embodiment shown in Figure 3. It can be seen that in the illustrated embodiment, the sleeve section 22 of the attachment body 8 is not flat, but curved radially inwards. The length L of the sleeve section 22 is again defined as the length from the underside of the end section 6 of the valve closing element 5 to the lower edge of the sleeve section 22 projecting into the combustion chamber 20. The attachment body 8 has a diameter D in the area of ​​the valve closing element 5. Ideally, L / D should also be 1 to 3.5 here. The wall thickness s of the sleeve section 22 is specifically s = (0.05 - 0.15) x L.

[0054] The sleeve section 22 of the attachment body 8 is not fully formed, but only extends over a partial region of its circumference. Advantageously, the sleeve section 22, shown in Figure 4, with length L, extends only over an angular range of, for example, 90° to 180°. Depending on the angular extent of the semicircular sleeve section 22, the gas flow 4 can be directed more or less precisely in desired directions. The inclination angle α of the sleeve section 22, deviating radially inward from the axially parallel perpendicular, is 0° to 60°. As shown, the inclination angle α of the sleeve section 22 is preferably between 30° and 60° in such a solution. On the side opposite the sleeve section 22, the gas flow 4 can exit axially parallel and, theoretically, collide deeper within the combustion chamber 20 with the gas flow 4 deflected by the sleeve section 22.If this is desired, the inclination angle a of the sleeve section 22 must be chosen to be correspondingly large.

[0055] The sleeve section 22 of the attachment body 8 is, for example, partially cylindrical downstream of the valve closing element 5 and thus axially parallel with a dimension a, where a = (0.15 - 0.5) x L shall apply. For the radius R1 of the bend following in the sleeve section 22, R1 = (0.25 - 0.5) x L shall apply.

[0056] Figure 5 shows a schematic sectional view of a cap-shaped attachment body 8 for an injector 1 for injecting a gaseous medium according to a third embodiment. This embodiment is similar to the embodiment shown in Figure 3, but is characterized in particular by a second sleeve section 22', which is formed, for example, opposite the sleeve section 22. The geometric parameters correspond to those of the two previously described embodiments. However, the two sleeve sections 22, 22' can differ in axial length L1, L2, angle of inclination a1, a2, and circumferential angular range β1, β2. For example, L2 can be, in particular, L1 = (0.25 - 0.5) x L1.

[0057] Figure 6 shows a schematic bottom view of the cap-shaped attachment body 8 along the arrows VI in Figure 5. Advantageously, the sleeve section 22 with length L1 shown in Figures 5 and 6 extends over an angular range β1 from, for example, 90° to 270°, while the opposite sleeve section 22' with length L2 covers only an angular range β2 between 45° and 90°. 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 a fourth embodiment. This embodiment is a modification of the embodiment according to Figure 5, in that both sleeve sections 22, 22' have radii. The geometric parameters are essentially the same as those of the three previously described embodiments.The two sleeve sections 22, 22' can differ in axial length L1, L2, angle of inclination a1, a2, radii of the curves R1, R2, and circumferential angular range β1, β2. For example, L2 can be defined as (0.25 - 0.5) x L1. The relationship between the two radii R1, R2 of the bends following the sleeve sections 22, 22' is given by R1 = (0.25 - 0.5) x L1.

[0058] R2 = (0.25 - 0.5) x R1 applies. With such geometric designs of the attachment bodies 8, optimized gas flows can be generated for improved and emission-reduced combustion of the gaseous fuel, especially hydrogen, in the combustion chamber 20.

[0059] Figure 8 shows a schematic sectional view of a cap-shaped attachment body 8 for an injector 1 for injecting a gaseous medium according to a fifth embodiment. The attachment body 8 is again designed as an open blowing cap 8, the sleeve section 22 of which extends, for example, over an angular range of approximately 180°, as can also be seen in particular in Figure 9, which shows a perspective view of the cap-shaped attachment body 8 for an injector 1 for injecting a gaseous medium according to the fifth embodiment. The sleeve section 22 extends downstream of the valve closing element 5 from the sealing seat 7, initially in a hollow cylindrical shape parallel to the axis over the desired angular range, here 180°, before pivoting at an oblique angle radially inwards, the end region pivoted at radius R1 having, for example, a greater wall thickness than the wall thickness of the hollow cylindrical section.The internal deflection occurs at a "sink-like" inner contour 9. In this way, attachment bodies 8, which are easily manufactured and assembled, can be provided to generate specifically desired gas flows in the combustion chamber 20. With attachment bodies 8, as shown in Figures 8 and 9, obliquely inclined, unilaterally directed beam patterns with an angle α from 0° to 60° can be generated.

[0060] Figure 10 shows a schematic sectional view of a cap-shaped attachment body 8 for an injector 1 for injecting a gaseous medium according to a sixth embodiment as a preferred and modified embodiment of the fifth embodiment. This modified embodiment of the embodiment shown in Figures 8 and 9 is characterized by a precisely matched length of the opposing sleeve sections 22 with axial lengths L1 and L2. Furthermore, particularly preferred geometric designs will be explicitly defined again with reference to this sixth embodiment.While on one side the sleeve section 22' with a short length L2 ends close to the end section 6 of the valve closing element 5, the opposite sleeve section 22 extends with a significantly longer axial length L1 and also has a bent end section 24, which forms a small base section, ensures the desired flow deflection, and nevertheless combines the advantages of an open blow-off valve. The end section 24, which serves to deflect the flow, has, for example, a wall thickness t that is 3 to 10 times greater than the wall thickness s of the sleeve sections 22, 22' in the axial extension area.

[0061] In absolute terms, the wall thickness s of the sleeve sections 22, 22' can be, for example, 0.4 mm, which results in a corresponding wall thickness t of approximately 1.2 mm to 4 mm for the end section 24. Ideally, the following relationships should also be satisfied: L1 = 1.5 ... 2.5 x t;

[0062] L2 = 0.2 .... 0.8 x L1 ; s = 0.05 .... 0.15 x L1 ;

[0063] L1 / D = 0.2 .... 0.8.

[0064] An axial distance x is defined between the underside of the end section 6 of the valve closing element 5 and the inner transition of the sleeve section 22 into the bent end region 24. The ratio of the outer diameter D of the attachment body 8 to this axial dimension x is defined as follows: x = 0.05 ... 0.25 x D, since the flow deflection is to occur relatively close to downstream of the end section 6 of the valve closing element 5. The deflection angle α of the end region 24 of the attachment body 8 relative to the horizontal should be between 5° and 50°, preferably between 5° and 30°, for optimized fluid deflection, particularly of the hydrogen to be discharged.

[0065] Figure 11 shows an isometric view of the cap-shaped attachment body 8 for an injector 1 for injecting a gaseous medium according to the sixth embodiment, in order to illustrate the geometry according to the invention particularly clearly. The very short axial length L2 of the sleeve section 22' and the significantly greater axial extent of the sleeve section 22 with length L1 are particularly evident. Furthermore, the design of the partially folded end region 24 is clearly shown.

[0066] Figure 12 shows a simplified bottom view of the cap-shaped attachment body 8 for an injector 1 for injecting a gaseous medium according to the fifth or sixth embodiment. In the illustrated embodiment, the angular range β1 = 180°. For the sleeve section 22 with length L1, the circumferential angular range β1 can be, for example, 90° to 270°, while the opposite sleeve section 22' with length L2 covers a complementary angular range β2 between 90° and 270°, or possibly only, for example, 45°. The following applies to the remaining open imaginary diameter of the attachment body 8 in the region of the end section 24: Di = 0.2 ... 0.8 x D.

[0067] The design features described above define an optimized attachment body 8 as an open blow cap that enables a gas spray directed laterally into the combustion chamber 20. The advantages of the embodiments shown specifically in Figures 8 to 12 are that a targeted spray pattern downstream of the sealing seat 7 is achieved via the geometry of a half-shell or a semi-open wall, while simultaneously ensuring the purging of the gaseous medium, particularly hydrogen. The radii R, R1 of the deflection geometry on the attachment body 8, as well as the angle α at the transition from the sleeve section 22 to the end region 24, enable a targeted spray pattern that can be adapted by the engine manufacturer to achieve the best possible purification results.The completely circumferential ring wall of the attachment body 8 enables the flow to be guided immediately after the sealing seat 7 and avoids jet interaction with the cylinder head wall (Coanda effects).

[0068] 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 include 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, thus ensuring optimized purging from the attachment body 8 at all times. The concept according to the invention allows for particularly high flexibility in designing the jet pattern. The gas flow can be distributed very evenly throughout the entire combustion chamber 20, which improves mixture formation and increases efficiency.

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-control geometry (10) downstream of the sealing seat (7), characterized in 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 region of the sealing seat (7), to which at least one sleeve section (22) extending over a circumferential region of the attachment body (8) and having an axial length (L, L1, L2) with an inner contour (9) is connected, which provides gas flow control. or guidance is enabled.

2. Injector according to claim 1, characterized in that the at least one sleeve section (22) of the attachment body (8) is oriented such that gas flow is directed or guided radially inwards.

3. Injector according to claim 1 or 2, characterized in that the length (L, L1 , L2) of the sleeve section (22) is defined as the length from the underside of an end section (6) of the valve closing element (5) to the lower edge of the sleeve section (22), wherein the attachment body (8) in the area the valve closing element (5) has a diameter (D) and the following applies: MD = 1 to 3.

5.

4. Injector according to one of the preceding claims, characterized in that the wall thickness (s) of the sleeve section (22) is: s = (0.05 - 0.15) x L.

5. Injector according to one of the preceding claims, characterized in that the sleeve section (22) of the attachment body (8) is not fully circumferential and is therefore partially circular.

6. Injector according to claim 5, characterized in that the at least one sleeve section (22) of the attachment body (8) extends only over a partial area of ​​the circumference, preferably over an angular range (β) of 90° to 270°.

7. Injector according to one of claims 5 or 6, characterized in that at least two spaced-apart and preferably opposing sleeve sections (22, 22') are provided on the attachment body (8).

8. Injector according to one of the preceding claims, characterized in that the at least one sleeve section (22) of the attachment body (8) is inclined or rounded or bent and has an inclination angle (a) of the sleeve section (22) radially inwards deviating from the axially parallel perpendicular between 0° and 60°.

9. Injector according to one of the preceding claims, characterized in that the attachment body (8) has two sleeve sections (22, 22') which are formed starting from the hollow cylindrical section as a common sleeve base, wherein the axial lengths (L1 , L2) of the sleeve sections (22, 22') can be clearly distinguished from each other and the sleeve section (22) with the greater axial length (L1) has an end region (24) that is bent radially inwards.

10. Injector according to claim 9, characterized in that the end region (24) serving to deflect the flow has a wall thickness (t) which is 3 to 10 times greater than the wall thickness (s) of the sleeve section (22, 22') in the axial extension area.

11. Injector according to one of the preceding claims, characterized in that the attachment body (8) with its flow control geometry (10) is attached to the injector (1) in such a way that the at least one sleeve section (22) projects beyond a boundary of a cylinder head (23) into a part of the combustion chamber (20).

12. Injector according to one of the preceding claims, characterized in that the flow control geometry (10) downstream of the sealing seat (7) is realized in a blow cap (8).

13. Injector according to one of the preceding claims, 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).

14. 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 disc-shaped.

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