Injector arrangement for injecting a gaseous medium

Abstract

The present invention relates to an injector arrangement comprising 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) which is downstream of the sealing seat (7) in terms of flow. The injector (1) is held in an opening (25) in a cylinder head (23) which, together with a combustion chamber roof, closes off the combustion chamber (20). According to the invention, the flow-influencing geometry (10) is made in such a way that it is formed downstream of the sealing seat (7) in an attachment body (8) and a contouring at the downstream end of the opening (25) in the cylinder head (23) at the transition to the combustion chamber roof assists the guidance of the flow by means of a geometric flow-influencing element (26).

Description

[0001] R. 414728

[0002] - 1 -

[0003] Description

[0004] title

[0005] Injector assembly for injecting a gaseous medium

[0006] State of the art

[0007] The present invention relates to an injector arrangement 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 arrangement with which hydrogen can be injected directly into the combustion chamber of a mixture-compressing, spark-ignition internal combustion engine.

[0008] 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). R. 414728

[0009] - 2 -

[0010] 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.

[0011] 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.

[0012] Disclosure of the invention

[0013] The injector arrangement 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 R. 414728

[0014] - 3 -

[0015] Claim 1, on the other hand, has the advantage that an optimized gas flow in the injector is made possible by the geometric design of a flow control geometry downstream of the sealing seat in conjunction with a flow control means on the cylinder head, 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.

[0016] 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.

[0017] 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.

[0018] The flow control geometry, which is housed in particular in a cap-shaped attachment body, or in short, a blowing cap, is characterized according to the invention in that the attachment body has an R. 414728

[0019] - 4 - has a hollow cylindrical section in the area of ​​the sealing seat, to which, in the direction of flow, a flow control device is connected in the transition from an opening serving to the combustion chamber roof of the cylinder head, which enables gas flow steering or guidance. In this way, in addition to improved scavenging behavior, mixture formation is improved in particular.

[0020] The dependent claims describe preferred embodiments of the invention.

[0021] Advantageously, the geometric flow control device is a chamfer at the downstream end of the cylinder head opening, which can be shaped in a highly variable way and yet adapted to the contours of various attachments on the cylinder head. In the simplest case, it resembles a chamfer.

[0022] In a particularly preferred manner, the injector attachment body extends obliquely at least over a partial region of its circumference on its downstream end face, wherein the angle of the beveled end face of the attachment body is taken up by the chamfer of the cylinder head to a largely equal extent.

[0023] The flow control geometry according to the invention is integrated into a very open mounting structure following the sealing seat. Such open 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.

[0024] The concept according to the invention allows for particularly high flexibility in the design of the jet pattern. The gas flow can be adjusted throughout the entire R. 414728

[0025] - 5 -

[0026] The combustion chamber is distributed very evenly, which improves mixture formation and increases efficiency.

[0027] 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.

[0028] In combination with the flow control device on the cylinder head, the invention is characterized by a defined flow contour of a largely open blow-off cap. With open blow-off caps, the incoming medium is guided stably from the sealing seat in order to introduce the injected medium, in particular hydrogen, into the combustion chamber with minimal loss of maximum flow velocity.

[0029] 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.

[0030] 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.

[0031] drawing

[0032] Preferred embodiments of the invention are described in detail below with reference to the accompanying drawing. The drawing shows: R. 414728

[0033] - 6 -

[0034] Figure 1 shows a schematic sectional view of an injector for injecting a gaseous medium according to the prior art.

[0035] Figure 2 shows a sectional view of a known cap-shaped attachment body for an injector according to Figure 1.

[0036] Figure 3 shows a schematic sectional view of an injector arrangement with a cap-shaped attachment body for an injector for injecting a gaseous medium according to a first embodiment.

[0037] Figure 4 shows a schematic sectional view of an injector arrangement with a cap-shaped attachment body for an injector for injecting a gaseous medium according to a second embodiment.

[0038] Figure 5 shows a schematic sectional view of an injector arrangement with a cap-shaped attachment body for an injector for injecting a gaseous medium according to a third embodiment.

[0039] Figure 6 shows a schematic sectional view of an injector arrangement with a cap-shaped attachment body for an injector for injecting a gaseous medium according to a fourth embodiment.

[0040] Figure 7 is a schematic sectional view of an injector arrangement with a cap-shaped attachment body for an injector for injecting a gaseous medium according to a fifth embodiment and R. 414728

[0041] - 7 -

[0042] Figure 8 shows a schematic sectional view of an injector arrangement with a cap-shaped attachment body for an injector for injecting a gaseous medium according to a sixth embodiment.

[0043] Preferred embodiments of the invention

[0044] 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 control geometry downstream of the valve seat are described below with reference to Figures 1 and 2.

[0045] 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 example, a magnetic actuator 21 is provided for actuating the injector 1, allowing the injector 1 to be controlled in a targeted manner.

[0046] The injector 1 also has a nozzle body 2 which, on the injection side, forms at its end a valve seat 3, e.g., conically shaped, 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 described in R. 414728.

[0047] - 8 - such that sufficient tightness is ensured during the operation of a hydrogen engine. In the event of a fault, a shut-off system, not shown here, which is installed upstream of injector 1 for safety reasons, would interrupt the supply of the gaseous medium, in particular 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.

[0048] 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.

[0049] 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.

[0050] 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 R. 414728

[0051] - 9 - characterized by an inner contour 9. Starting from a cylindrical section 11 of the sleeve 8, following the valve closing element 5 in the flow direction, a reduction in cross-section occurs at a large axial distance to 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.

[0052] 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.

[0053] The reduction in cross-section is reversed by the fact that the central axial region 13 is followed by a conically extending section 1, in this case widening conically in the flow direction, with this section 1 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.

[0054] 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.

[0055] 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 of the injector 1, with which optimal combustion results are achieved according to R. 414728

[0056] - 10 - flow guidance according to the invention is achieved. This optimized flow guidance is to be achieved primarily in interaction with a geometry of a cylinder head 23 in which an opening 25 for receiving the injector 1 is provided, in the flow-technically continued area of ​​the sealing seat 7.

[0057] 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.

[0058] Furthermore, injection systems for direct (hydrogen) injection inherently require a large stroke of the valve needle with the valve closing element 5. Designing the magnetic circuit (magnetic actuator 21) with 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 beam guidance system is also intended to reduce the magnetic force.

[0059] The core of the invention consists in shaping the internal flow of the gaseous medium with as little loss as possible via the inventive internal 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 directed precisely into the combustion chamber 20. This defined internal contour 9 is aimed in particular at improved mixture formation. Due to the highly variable contouring of the internal contour 9, a very flexible use of sleeves or R. 414728 is possible.

[0060] - 11 -

[0061] Attachment bodies 8 on injectors 1 are enabled. In the manner of the invention, the injector arrangement with the injector 1 is designed such that a contouring at the downstream end of the largely cylindrical opening 25 of the cylinder head 23 in the transition to the combustion chamber roof, by means of a geometric flow control means 26, in particular a means referred to as a chamfer 26, significantly improves the scavenging behavior and flow guidance.

[0062] In principle, open or semi-open attachment bodies 8, which are designed, for example, as jet-shaping caps, allow for improved scavenging behavior and thus greater robustness against pre-ignition in hydrogen combustion engines than is the case with largely closed attachment bodies with bottom sections. However, this advantage is offset by a somewhat limited jet guidance. Therefore, according to the invention, the cylinder head 23, with its geometric design, is to be integrated into the improved jet guidance, encompassing the flow control element 26.

[0063] The following section describes injector arrangements with injectors 1, featuring flow-influencing geometries 10 on the injector 1 and flow-influencing means 26 on the cylinder head 23, according to preferred embodiments of the invention, with reference to Figures 3 to 8. As mentioned previously, the flow-influencing geometries 10 of the injector 1 can be formed directly as a single 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 (or simply blow cap 8). The attachment body 8 typically has a significantly lower R. 414728

[0064] - 12 -

[0065] The overlap length with the nozzle body 2 must be greater 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. Common joining methods such as pressing, welding, soldering, gluing, or combinations thereof can be used.

[0066] 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 a simple 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 other chamfers or radii on its outer contour.

[0067] Figure 3 shows a schematic sectional view of an injector arrangement with the injector 1 for injecting a gaseous medium and the cylinder head 23 in the region of its combustion chamber roof according to a first embodiment. The injector 1, with its injection-side end, is shown in an installation position in the opening 25 of the cylinder head 23 of an internal combustion engine, which serves to receive the injector 1. 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. In contrast to all other embodiments in Figures 4 to 8, the flow-influencing geometry 10 of the injector 1, and thus the attachment body 8, does not project beyond the boundary of the cylinder head 23 forming the combustion chamber roof, particularly not into a part of the combustion chamber 20.The attachment body 8 of the embodiment according to Figure 3 ends inside the opening 25. R. 414728.

[0068] - 13 -

[0069] The flow control geometry 10 generated by the inner contour 9 has a key geometric characteristic, primarily a radial outward deflection of the gas flow in a downstream direction. This is achieved by the downstream end face of the attachment body 8 being inclined and tapering conically. In the example shown in Figure 3, the lower end face of the attachment body 8 does not necessarily terminate at the same axial height all around; a slight offset around the circumference may be provided to generate different injection angles. The arrows with reference numeral 4 are intended to illustrate the gas flow 4. In a particularly simple embodiment, the attachment body 8 terminates at exactly the same height all around, and its downstream end face has the same chamfer all around.As already mentioned, according to the invention the opening 25 of the cylinder head 23 also has a geometric flow control means 26 at the end of its cylindrical extension in the transition to the combustion chamber roof, which is in particular designed as a chamfer 26 and with which the jet guidance is further ideally supported.

[0070] The flow control element 26 on the cylinder head 23 is specifically designed as a chamfer 26, which can be shaped like a bevel and ideally incorporates the angle of the chamfered end face of the attachment body 8, so that the gas flow 4 can flow past the cylinder head 23 into the combustion chamber 20 without obstruction. Due to its ease of manufacture, the chamfer 26 can be uniformly inclined and planar, but it can also have a certain radius, so that slightly convex or concave chamfers 26 are also conceivable. The angle of the chamfer 26 is denoted by a. This can be identical to the angle of the lower end face of the attachment body 8. The residual angle to the central axis is denoted by s, such that s = 90° - a. R. 414728

[0071] - 14 -

[0072] The chamfer 26 with angle α on the wall of the cylinder head 23 significantly improves flow guidance. The angle α should be within a range of 5° < α < 45°. The chamfer 26 enables close-to-wall guidance with low flow losses and, consequently, greater penetration depths into the combustion chamber 20. This allows for high flexibility in the target range of the spray angle, denoted by s.

[0073] Figure 4 shows a schematic sectional view of an injector arrangement with a cap-shaped attachment body 8 for an injector 1 for injecting a gaseous medium according to a second embodiment. The attachment body 8 is again designed as an open blow-off cap 8, which has a sleeve section 22 that projects beyond the chamfer 26 and the combustion chamber roof into the combustion chamber 20, and whose sleeve section 22 extends, for example, over an angular range of approximately 180°, while on the opposite side, the attachment body 8 also extends approximately 180° around the opening 25 of the cylinder head 23. The sleeve section 22 runs downstream of the valve closing element 5, coming from the sealing seat 7, initially in a hollow cylindrical shape parallel to the axis over the desired angular range, here 180°, before pivoting radially inwards at an oblique angle, with the pivoted end region, for example,It has 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 easy to manufacture and assemble, can be provided to generate specifically desired gas flows in the combustion chamber 20. With attachment bodies 8, as shown in Figures 4 to 8, obliquely inclined, unilaterally directed jet patterns at an angle from 0° to 60° can be generated. R. 414728.

[0074] - 15 -

[0075] While the short end of the attachment body 8, together with the chamfer 26 on the cylinder head 23, already defines an angle of gas flow 4, an appropriate flow angle can now be generated on the opposite side of the attachment body 8 by means of the sleeve section 22. For this purpose, a bent end section 24 extends from the sleeve section 22, forming a certain base section and ensuring the desired flow deflection, while still retaining the advantages of an open blow-off cap. The end section 24, which serves to deflect the flow, has, for example, a wall thickness that is 3 to 10 times greater than the wall thickness of the sleeve section 22 in its axial extent.

[0076] Figures 5 and 6 show schematic sectional views of an injector arrangement, each with a cap-shaped attachment body 8 for an injector 1 for injecting a gaseous medium, according to a third and a fourth embodiment. These examples differ only slightly from the design of the attachment body 8 according to Figure 4.

[0077] For further stabilization of the flow guidance, sub-variants of the attachment body 8 in the form of semi-open blow-off caps are conceivable through defined shaping of the inner contour 9. These variants provide in particular for a targeted design of the transition from the sleeve section 22 to the end region 24 as well as the design of the end region 24 of the attachment body 8 itself. In a particularly suitable manner, the shaping of the end region 24 of the attachment body 8 with an angle β can be adapted to the angle α of the chamfer 26 on the cylinder head 23 in order to generate specifically desired one-sided or asymmetrical injection patterns in the combustion chamber 20. R. 414728

[0078] - 16 -

[0079] The attachment bodies 8 vary primarily in the end region 24 in terms of the wall thickness, the radial extension of the end region 24 inwards towards the central axis, the size of the radius in the transition from the sleeve section 22 to the end region 24 and the geometry of the downstream termination of the end region 24.

[0080] The angles β of the inner contour 9 in the end region 24 of the attachment body 8 are, for example, in the range of 35° to 75° (Figure 5) or in an angle range with angles β of 5° to 40° (Figure 6).

[0081] Figures 7 and 8 show schematic sectional views of an injector arrangement, each with a cap-shaped attachment body 8 for an injector 1 for injecting a gaseous medium, according to a fifth and a sixth embodiment. These examples differ only slightly from the design of the attachment body 8 according to Figure 4 and the embodiments according to Figures 5 and 6.

[0082] For further stabilization of the flow path, sub-variants of the attachment body 8 in the form of semi-open blow caps are also conceivable through defined shapes of the end section 6 of the valve closing element 5. Figures 7 and 8 each show a cap-shaped attachment body 8 in which a modified valve closing element 5 is present, the end section 6 of which has an additional flow shaper 27 that, deviating from the actual disc-shaped form, has a downstream contour. The flow shaper 27 can, for example, be a conical (Figure 7) or stepped conical tip centrally located on the valve closing element 5 with a flow angle y > e.g., ranging from 10° to 40° (Figure 8), or a cylindrically shaped needle tip. The diameter of the flow shaper 27 at its upstream beginning can be equal to, but also larger (Figure 8) or smaller (Figure 7) than the diameter of the valve needle shaft. The flow shaper 27 can, for example,B. also starting from the radial outer contour of R. 414728.

[0083] - 17 -

[0084] extend the end section 6 of the valve closing element 5 in a downstream direction.

[0085] In general, the flow former 27 can be described as follows: on the downstream underside of the end section 6 of the valve closing element 5, an additional axial component is provided in the downstream direction, deviating from its largely disc-shaped design. This component thus forms part of the flow-influencing geometry 10 of the valve closing element 5. The axial length of the flow former 27 should be less than the axial length of the sleeve section 22 or the free outlet length of the flow to the end region 24 when the sealing seat 7 is maximally open and thus at maximum valve needle lift. Depending on the geometric design of the flow former 27, the following should apply: h2 = h1 ± 0.5 mm, where h1 is the axial distance from the lower edge of the end section of the valve closing element 5 to the end of the inner contour 9 at the end region 24 of the attachment body 8, and h2 is the axial length of the flow former 27.

[0086] The flow former 27 on the downstream underside of the valve closing element 5 stabilizes the internal flow immediately downstream of the valve disc and reduces the forces acting there. The effects on the stiffness of the valve needle are limited by the corresponding dimensions of the flow former 27 shown above.

[0087] These variants therefore provide, in particular, for a targeted design of the valve closing element 5 with the end section 6. The shaping of the end region 24 of the attachment body 8 with an angle β, in conjunction with the flow shaper 27 of the valve closing element 5, allows for a particularly suitable adaptation to the angle α of the chamfer 26 on the cylinder head 23, in order to generate specifically desired one-sided or asymmetrical injection patterns in the combustion chamber 20. R. 414728

[0088] - 18 -

[0089] The attachment bodies 8 can also vary here, especially in the end region 24, with regard to the size of the wall thickness, the radial extension of the end region 24 inwards towards the central axis, the size of the radius in the transition from the sleeve section 22 to the end region 24 and the geometry of the downstream termination of the end region 24.

[0090] The angles β of the inner contour 9 in the end region 24 of the attachment body 8 can be of the same order of magnitude as in the examples according to Figures 5 and 6, i.e. ideally in the range of 5° to 75°.

[0091] Overall, the attachment body 8 is always designed as an open or semi-open blow-off body, meaning that the thin-walled sleeve contour of the overlapping area for attachment to the nozzle body 2 largely continues downstream, although variations in wall thickness along the axial length of the attachment body 8 are conceivable. Such open attachment bodies 8 offer 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.

[0092] As already described, 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 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 angle of inclination of the sleeve section 22 radially inward from the axially parallel perpendicular is 0° to 60°. Angles of inclination of the sleeve section 22 are preferably between 10° and 45°. R. 414728

[0093] - 19 -

[0094] In absolute terms, the wall thickness of the sleeve sections can be, for example, 0.4 mm, which results in a wall thickness of approximately 1.2 mm to 4 mm for the end area 24.

[0095] 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 4 to 8 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 in combination with a flow control device 26 on the cylinder head 23, while simultaneously ensuring the purging of the gaseous medium, in particular hydrogen. The radii of the deflection geometry on the attachment body 8, as well as the angle 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 purging 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).

[0096] The angle α of the chamfer 26 on the cylinder head 23 ideally remains constant over the entire circumference. However, it can also vary over the circumference or be provided only in a partial area, in which case the chamfer 26 preferably extends over at least 30° to 180°.

[0097] In addition to the optimized beam guidance, which is made possible by the attachment body 8 according to the invention in combination with the cylinder head 23, further advantages of the attachment body 8 designed in this way are the increased strength and improved thermal conductivity. Avoiding R. 414728

[0098] - 20 - Due to the absence of back pressure downstream of the sealing seat 7, there is a high degree of pressure independence in this area, so that optimized purging from the attachment body 8 is always possible. The concept according to the invention allows for particularly high flexibility in designing the spray pattern. The gas flow can either be distributed very uniformly throughout the entire combustion chamber 20, which improves mixture formation and increases efficiency, or directed very specifically to desired areas of the combustion chamber 20.

Claims

R. 414728 - 21 - Claims 1. Injector arrangement for injecting a gaseous medium, in particular a gaseous fuel, preferably hydrogen, into a combustion chamber (20) of an internal combustion engine, comprising an injector (1) with 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) downstream of the sealing seat (7), and a cylinder head (23) terminating the combustion chamber (20) with a combustion chamber roof, which has an opening (25) for receiving the injector (1), characterized in that the flow-influencing geometry (10) is located downstream of the sealing seat. (7) is formed in an attachment body (8) on the injector (1) and a contouring at the downstream end of the opening (25) of the cylinder head (23) in the transition to the combustion chamber roof supports the flow guidance by means of a geometric flow control device (26).

2. Injector arrangement according to claim 1, characterized in that the geometric flow control means (26) is a chamfer (26) at the downstream end of the opening (25) of the cylinder head (23).

3. Injector arrangement according to claim 2, characterized in that the chamfer (26) is conically widening, uniformly inclined and planar. R. 414728 - 22 - or alternatively has a radius, resulting in a slightly convex or concave contour.

4. Injector arrangement according to claim 2 or 3, characterized in that the attachment body (8) of the injector (1) is inclined at least over a partial region of its circumference on its downstream end face and the angle of the beveled end face of the attachment body (8) is taken up to a largely equal extent by the chamfer (26) of the cylinder head (23).

5. Injector arrangement according to one of claims 2 to 4, characterized in that the angle (a) of the chamfer (26) lies in an angular range of 5° < a < 45°.

6. Injector arrangement according to one of claims 2 to 5, characterized in that the angle (a) of the chamfer (26) on the cylinder head (23) is constant over the entire circumference.

7. Injector arrangement according to one of claims 2 to 5, characterized in that the chamfer (26) on the cylinder head (23) is provided at least in a partial area over the circumference, wherein the chamfer (26) then preferably extends over at least 30° to 180°.

8. Injector arrangement according to one of the preceding claims, characterized in that the flow control geometry (10) of the injector (1) and thus the attachment body (8) ends inside the opening (25) of the cylinder head (23) and thus does not project into the combustion chamber (20) beyond the boundary of the cylinder head (23) forming the combustion chamber roof.

9. Injector arrangement according to one of claims 1 to 7, characterized in that the flow control geometry (10) of the injector (1) includes at least one sleeve section (22) of the attachment body (8) R. 414728 - 23 - includes, which projects into the combustion chamber (20) and which is oriented in such a way that gas flow is directed or guided radially inwards.

10. Injector arrangement according to claim 9, characterized in that the sleeve section (22) of the attachment body (8) is not fully circumferential and is therefore partially circular.

11. Injector arrangement according to claim 10, 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 of 90° to 270°.

12. Injector arrangement according to claim 10 or 11, characterized in that an end region (24) of the attachment body (8) serving to deflect the flow has a wall thickness at the end of the sleeve section (22) which is 3 to 10 times greater than the wall thickness of the sleeve section (22) in the axial extension area.

13. Injector arrangement 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).

1. Injector arrangement 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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