Injector for injecting a gaseous medium

Abstract

The 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-influencing geometry (10) positioned downstream of the sealing seat (7) in terms of flow. According to the invention, the flow-influencing geometry (10) is integrated into a multipart attachment body (8), wherein the attachment body (8) comprises a cap-shaped main part (23) which can be secured to a nozzle body (2) of the injector (1), and the main part (23) has a receiving opening (25), into which an insert part (24) can be inserted and in which the insert part can be secured, said insert part (24) having the geometries responsible for the jet formation process and comprising the outlet (19) of the attachment body (8).

Description

[0001] Description

[0002] title Medium

[0003] State of the art

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

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

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

[0007] Disclosure of the invention

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

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

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

[0011] The cap-shaped attachment body, which can also be referred to as a blow cap for short, has a particularly designed flow influencing geometry and is characterized according to the invention in that the flow influencing geometry is integrated in a multi-part attachment body, wherein the attachment body comprises a cap-like base body which can be fastened to a nozzle body of the injector, and the base body has a receiving opening into which an insert part can be inserted and fastened there, wherein the insert part contains the geometries responsible for the jet shaping with the outlet of the attachment body.

[0012] The multi-part design of the attachment body advantageously offers a great deal of flexibility in jet design, as the geometry of the insert allows for a wide range of jet guidance options. Using one or a few reference injectors, several design variants of the attachment body can be tested on a single-cylinder or multi-cylinder engine, or in a jet chamber. This allows for faster sampling of the various design variants. Replacing or dismantling an insert part on the attachment bodies is relatively straightforward at any time. Advantageously, only a few design variants are required for the base body of the attachment body, allowing a very broad spectrum of flow designs to be represented despite the variety of insert parts.Above all, with such a multi-part solution according to the invention, very complex design variants can be easily implemented in terms of manufacturing technology.

[0013] The subclaims describe preferred developments of the invention.

[0014] It is particularly advantageous to firmly and securely connect the insert and the base body. The insert is precisely fitted into a receiving opening in the base body of the attachment body and secured, in particular, by means of a screw connection, so that the attachment body forms a complete unit. When installed, the insert with the outlet advantageously protrudes beyond the lower end face of the base body to solely assume the jet shaping function.

[0015] It is also advantageous if a jet splitter serving as a flow rocker is provided on the insert part, which projects from the insert part into the base body against the flow direction in order to be able to divide the flow in the attachment body at an early stage.

[0016] In particular, it is advantageous if a flow deflector protrudes from the insert in the downstream direction. This deflection geometry is either uniformly circumferential or has multiple deflection segments along the circumference. Asymmetric design variants are particularly advantageous when the injector is installed laterally on the cylinder head. This can significantly improve mixture formation; higher efficiency can be achieved; and combustion anomalies can be reduced.

[0017] A geometry design for the tapered first section is particularly advantageous if the following relation applies at maximum needle stroke lh of the valve closing element: 5 x lh > s > 1 ,5 x lh, where s is the distance between the radially outer contour of the

[0018] Valve closing element at its downstream edge region and the ring line lying axially below it in a projection on a section of the flow influencing geometry tapering in the flow direction in order to generate a virtually loss-free flow downstream of the valve closing element.

[0019] It is particularly advantageous that the section of the flow-influencing geometry that tapers in the direction of flow downstream of the valve closing element is largely conical. It is advantageous that the angle of inclination a of the inner contour in the region of the tapered section is 85° > a > 30°, preferably > 45°.

[0020] This inner contour defined according to the invention, with its special features in shape and design, can be advantageously accommodated in attachment bodies with reducible external dimensions. This, in turn, enables very flexible use of sleeves or attachment bodies on injectors in various combustion chamber geometries of internal combustion engines.

[0021] The present invention is preferably used in injection systems that inject hydrogen directly into a combustion chamber. In particular, the injector is suitable for directly injecting hydrogen into the combustion chamber of an internal combustion engine.

[0022] drawing

[0023] Preferred embodiments of the invention are described in detail below with reference to the accompanying drawings. In the drawing:

[0024] Figure 1 is a schematic sectional view of an injector for injecting a gaseous medium according to the prior art,

[0025] Figure 2 is a sectional view of a known cap-shaped attachment body for an injector according to Figure 1,

[0026] 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, Figure 4 is a schematic sectional view of a cap-shaped attachment body for an injector for injecting a gaseous medium according to a second embodiment,

[0027] Figure 5 is a schematic sectional view of a cap-shaped attachment body for an injector for injecting a gaseous medium according to a third embodiment,

[0028] Figure 6 is a schematic sectional view of a cap-shaped attachment body for an injector for injecting a gaseous medium according to a fourth embodiment,

[0029] Figure 7 is a schematic sectional view of a cap-shaped attachment body for an injector for injecting a gaseous medium according to a fifth embodiment,

[0030] Figure 8 is a schematic sectional view of a cap-shaped attachment body for an injector for injecting a gaseous medium according to a sixth embodiment,

[0031] Figure 9 is a schematic sectional view of a cap-shaped attachment body for an injector for injecting a gaseous medium according to a seventh embodiment, Figure 10 is a schematic sectional view of a cap-shaped attachment body for an injector for injecting a gaseous medium according to an eighth embodiment,

[0032] Figure 11 is a schematic sectional view of a cap-shaped attachment body for an injector for injecting a gaseous medium according to a ninth embodiment,

[0033] Figure 12 is a schematic sectional view of a cap-shaped attachment body for an injector for injecting a gaseous medium according to a tenth embodiment,

[0034] Figure 13 is a schematic sectional view of a cap-shaped attachment body for an injector for injecting a gaseous medium according to an eleventh embodiment and

[0035] Figure 14 is a schematic bottom view of the attachment body according to Figure 13.

[0036] Preferred embodiments of the invention

[0037] 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-influencing geometry arranged downstream of the valve seat in terms of flow technology are described below with reference to Figures 1 and 2. Figure 1 shows a schematic section of the known injector 1 for injecting a gaseous medium. Since the invention is directed to the flow-influencing geometry 10 arranged downstream of the valve seat 3 in terms of flow technology, only this assembly will be described in more detail here for the known injector 1. For actuating the injector 1, for example, a magnetic actuator 21 is provided so that the injector 1 can be specifically controlled via this.

[0038] The injector 1 also has a nozzle body 2, which on the injection side forms a valve seat 3, for example a conically shaped valve seat, for a valve closing element 5 that opens outwards, i.e., opens towards a combustion chamber 20. The valve closing element 5 is guided axially movably within the nozzle body 2 via a guide 18. In addition, the valve closing element 5 has an end section 6 in the form of a valve disk, which forms a sealing seat 7 corresponding to the valve seat 3. The two sealing seat partners, valve seat 3 and valve closing element 5, are each made of metal. The geometric and material design is such that sufficient tightness is guaranteed during operation of a hydrogen engine.In the event of a fault, a shut-off system (not shown here) installed upstream of the injector 1 for safety reasons would interrupt the supply of the gaseous medium, particularly the highly volatile hydrogen. The sealing contour of the end section 6 of the valve closing element 5 is, for example, rounded, while the valve seat 3 on the nozzle body 2 has a conical shape. However, other contours are also conceivable.

[0039] The nozzle body 2 and the end section 6 of the valve closing element 5 are surrounded by a sleeve 8 for jet shaping. In the following, and in particular with reference to the invention, reference is generally made to a flow-influencing geometry 10 arranged downstream of the sealing seat 7 in terms of flow technology. This can either be formed directly as a single piece on the nozzle body 2, which, however, requires a high manufacturing outlay, or it can be integrated into an additional component, which, with reference to the prior art embodiments in Figures 1 and 2, is generally referred to as a sleeve 8. The sleeve 8 has a large overlap length with the nozzle body 2 in order to be able to fasten the sleeve 8 securely and reliably. In principle, however, reference can also be made to a cap-shaped attachment body 8, which, with reference to the exemplary embodiments according to the invention, is also defined as a blow cap 8.

[0040] The sleeve 8 and the end section 6 of the valve closure element 5 jointly define a gas flow path 4, into which at least one intake channel 15 formed in the sleeve 8 opens. Air from the environment can be drawn into the gas flow path 4 via the one or more intake channels 15.

[0041] If the valve closing element 5 is in an open position lifted from the valve seat 3, the gas flow path 4 then leads via the valve seat 3 into an interior of the sleeve 8, which is characterized by a special shape with an inner contour 9. Starting from a cylindrical section 11 of the sleeve 8 and following the valve closing element 5 in the direction of flow, a cross-sectional reduction occurs at a large axial distance from the valve closing element 5 in a central cylindrical axial region 13 of the flow-influencing geometry 10 of the sleeve 8, with the taper being achieved via a conically running section 12 in the inner contour 9 of the sleeve 8. The intake channels 15 open into the inner contour 9 of the sleeve 8 precisely in the central axial region 13.

[0042] The reduction in cross-section within the gas flow path 4 ensures that, as the gas flows out through the gas flow path 4 toward an outlet 19, air is drawn from the environment into the gas flow path 4 via the intake channels 15 (“Venturi effect”). This means that air is mixed with the gas before it reaches the outlet 19, thus improving the mixture preparation.

[0043] The cross-sectional reduction is offset by the fact that the central axial region 13 is again followed by a conical section 14, but in this case widening conically in the direction of flow, with this section 1 extending to the outlet 19. The cross-sectional reduction in the inner contour 9 of the sleeve 8 is intended to achieve the Venturi effect, which is optimized together with the air admixture.

[0044] Experience has shown that with such a solution or with other known geometries or inner contours of cap-shaped attachment bodies, sufficiently good results are not achieved with regard to the introduction of the jets into the combustion chamber 20 or their jet guidance and jet shaping for optimal combustion.

[0045] Therefore, the object of the invention is to provide an inner contour 9 of a cap-shaped attachment body 8 with a flow-influencing geometry 10 arranged downstream of the sealing seat 7, with which optimal combustion results are achieved due to the flow guidance according to the invention.

[0046] Injection systems for the direct injection of a gaseous medium, in particular hydrogen, but also CNG, methane, ammonia or mixtures of the aforementioned gases, have the task of specifically controlling the dosage as well as the injection direction of the gas jet(s) into the combustion chamber 20 via injection valves or, in general, injectors 1. For this purpose, corresponding sleeves or blow caps 8 can be used on the injector 1, as already explained above. Furthermore, injection systems for the (hydrogen)-

[0047] Direct injection, by its very nature, requires a large lift of the valve needle with the valve closing element 5. Designing a magnetic circuit (magnetic actuator 21) using standard materials is very difficult, or in some cases impossible, due to the limited installation space. Materials with higher magnetic force and thus better B / H characteristics are very expensive and sometimes even harmful to health (e.g., FeCo). Therefore, a reduction in magnetic force should also be achieved through improved jet guidance.

[0048] The core of the invention is to design the internal flow of the gaseous medium with as little loss as possible via the inventive inner contour 9 of the cap-shaped attachment body 8, so that the back pressure located below, i.e., downstream of the plate-shaped end section 6 of the valve closing element 5 is reduced and, at the same time, the jet can be introduced into the combustion chamber 20 in a targeted manner. This defined inner contour 9, with its special features in shape and design, can advantageously be accommodated in attachment bodies 8 with reducible external dimensions. This, in turn, enables a very flexible use of sleeves or attachment bodies 8 on injectors 1 in various combustion chamber geometries of internal combustion engines.

[0049] Injectors 1 with attachment bodies 8 according to the invention, with flow-influencing geometries 10 arranged downstream of the valve seat 3 in terms of flow technology, are described in detail below with reference to Figures 3 to 14, according to preferred exemplary embodiments of the invention. According to the invention, the cap-shaped attachment body 8 is designed in several parts. The attachment body 8 will usually have a significantly shorter overlap length 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, which enables perfect and axially parallel alignment with the injector 1. Known joining methods such as pressing, welding, soldering, gluing, or combinations thereof can be used.Figure 3 shows a first embodiment of a flow-influencing geometry 10 arranged downstream of the valve seat 3 in a cap-shaped attachment body 8 and created by an inventive inner contour 9. The valve closing element 5 with its plate-shaped end section 6 is shown only schematically and in a simplified manner. However, the end section 6 can also have chamfers or rounded portions on its outer contour.

[0050] The attachment body 8 comprises a cap-like base body 23, which can be fastened to the nozzle body 2 of the injector 1, as already mentioned above. At its downstream end, the base body 23 of the attachment body 8, with its inner contour 9, merges into a receiving opening 25, into which an insert part 24 can be inserted and fastened. The insert part 24 is a compact, separately manufactured and largely cylindrical individual component that contains the geometries responsible for jet shaping up to the outlet 19 of the attachment body 8. The receiving opening 25 of the base body 23 is designed such that the insert part 24 can be inserted with a precise fit from the downstream side of the base body 23. As shown in Figure 3, a screw connection 22 between the insert part 24 and the base body 23 of the attachment body 8 can ensure a firm and secure connection.Nevertheless, with this choice of connection technology it is possible to replace the insert part 24 with another insert part by loosening the screw connection 22.

[0051] The insert part 24 is, for example, inserted so deeply into the receiving opening 25 of the base body 23 until it rests against a stop shoulder of the base body 23. In the installed state, the insert part 24 with the outlet 19 can protrude beyond the lower end face of the base body 23, so that the geometry of the inner contour 9 of the insert part 24 is solely responsible for the jet shaping and there is no influence from the outer contour of the base body 23. In the first embodiment of an attachment body 8 shown in Figure 3, the insert part 24 has an inner contour 9 which first has a trough-like inlet region 30, from which several outlet bores 31 lead to the outlet 19. The outlet bores 31 can be designed as oblique bores. A central outlet bore 31 can, for example, as shown, also run parallel to the axis.Ideally, between two and ten outlet holes 31 are provided to achieve a homogeneous jet distribution.

[0052] In addition to the flow influencing geometry 10 introduced into the insert part 24 via the inner contour 9, the base body 23 upstream of the insert part 24 also already has several interesting aspects and geometric specifications, with the relationship between two surfaces being an essential criterion. To be precise, the two surfaces As and Ai are considered, which result at maximum valve needle lift lh, i.e. when the sealing seat 7 is maximally open and the valve closing element 5 is thus maximally lifted. The surface As represents the annular seat cross-sectional area that results between the valve seat 3 and the contact line of the end section 6 of the valve closing element 5, while the surface Ai is determined by the distance that results from the shortest route between the outer contour of the valve closing element 5 at its downstream edge region and the opposite wall of the inner contour 9.In other words, the area Ai represents the narrowest cross-section below the valve closing element 5 when the sealing seat 7 is fully open. This area Ai is also annular and, as an imaginary surface, is located, here at approximately a right angle, on a tapering, in particular conically extending section 12 in the inner contour 9 of the.

[0053] Attachment body 8, which ensures a significant taper of the inner contour 9 over a short axial extent, which also advantageously contributes to the desired optimized flow result. The ratio of the areas As and Ai should be: Ai > 2.5 x As. The jet guidance coming from the sealing seat 7 takes place via the inner contour 9 in the conical section 12, which is designed with an inclination angle a of 85° > a > 30°, preferably with an inclination angle a of > 45°. With this relatively large angle a of the conical section 12, a strong radially inward-directed flow component is generated over a very short axial extent. The lines of the flow path 4 illustrate this.

[0054] A further characteristic of the design of the inner contour 9 is the distance s which results at maximum needle lift lh between the radially outer contour of the valve closing element 5 at its downstream edge region and the ring line lying axially below it in a projection on the conical section 12. The following should apply: 5 x lh > s > 1.5 x lh in order to generate a virtually loss-free flow around the end section 6 of the valve closing element 5. In particular, for an optimized flow result, 4 x lh > s > 2.5 x lh applies. The maximum needle lift lh extends over an axial extension length of 100 pm to 2 mm, whereby the maximum needle lift lh will ideally be between 0.15 mm and 0.5 mm.

[0055] As a result of these geometric specifications, a flow redirection takes place over a short axial distance in the area of ​​the valve closing element 5 from a large diameter in the area of ​​the sealing seat 7 to a significantly smaller diameter with an inner surface A2 at the end of the tapered, in particular conical, section 12, so that in this area immediately downstream of the valve closing element 5, flow deflection advantageously takes place in the form of an "S-bend". Instead of the conical shape of section 12, this section 12 can also have a slightly convex or slightly concave curvature. In addition to the ratio of the flow cross sections corresponding to Ai > 2.5 x As, the following should therefore also apply to the flow cross sections of the areas As and A2: 5 x As > A2 > 2 x As, so that a supercritical flow is ensured and a limitation of back pressures below the valve closing element 5 is achieved.

[0056] This is also associated with the acceleration of the flow in the direction of the insert part 24, which is characterized by the axial region 13 following the conical section 12 in the flow direction, with a reduction in losses or turbulence in the wall region and an approximation of the effective flow cross-section to the geometric cross-sectional area A2. The axial region 13 is ideally a cylindrical hole section that merges directly into the receiving opening 25. While the first conical section 12 immediately downstream of the valve closing element 5 ensures a strong flow deflection, the axial region 13, as the second downstream section, is responsible for generating high jet stability. In addition, a reduction in losses or turbulence in the wall region is achieved, whereby overall an almost effective filling of the flow cross-section in the cylindrical axial region 13 is possible.A bore diameter as small as possible in the axial area 13 contributes to reducing the dead volume.

[0057] 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 exemplary embodiment. The insert part 24, which is again fastened in the base body 23 by means of a screw connection 22, has an inner contour 9 with a single outlet bore 31. This outlet bore 31 has a short cylindrical section, to which an oblique and conically tapered section of the outlet bore 31 adjoins in order to create an asymmetrical, one-sided jet pattern.

[0058] 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 exemplary embodiment. The insert part 24 has, for example, between two and ten outlet bores 31, which can be designed as inclined bores. The special feature of the solution shown in Figure 3 is a jet splitter 26 serving as a flow rocker or spoiler, which, as shown, tapers to a point or can be designed with a small plateau. Alternatively, the jet splitter 26 can also be rounded. The jet splitter 26 projects from the insert part 24 against the direction of flow into the axial region 13 and possibly also into the conically running section 12 of the base body 23, so that the flow can be divided early on in the attachment body 8.A screw connection 22 is provided for the firm connection of insert part 24 and base body 23.

[0059] 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 a fourth exemplary embodiment. The insert part 24 has, for example, between two and ten outlet bores 31, which can be designed as inclined bores, but have an orientation converging radially inwards towards the central axis. The jet splitter 26, which serves as a flow rocker or spoiler, has a large-area plateau, from which flow can be guided along the jet splitter 26 to the outlet bores 31. Alternatively, the jet splitter 26 can also be rounded. The jet splitter 26 projects from the insert part 24 against the direction of flow into the axial region 13 and possibly also into the conically extending section 12 of the base body 23, so that flow division can be carried out early on in the attachment body 8.A screw connection 22 is provided for the firm connection of insert part 24 and base body 23.

[0060] 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 fifth exemplary embodiment. This solution is very similar to the exemplary embodiment shown in Figure 4. The insert part 24, which is again fastened in the base body 23 by means of a screw connection 22, for example, has an inner contour 9 with two outlet bores 31. The outlet bores 31 have a common short cylindrical section, to which, on the one hand, an oblique and also conically tapered section of the first outlet bore 31 and, on the other hand, a largely axially parallel and, for example, also conically tapered section of the second outlet bore 31 are connected in order to produce an asymmetrical jet pattern.

[0061] 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 sixth exemplary embodiment. In this solution, a single outlet bore 31 formed as a central bore is provided. The insert part 24, which is in turn fastened in the base body 23 by means of a screw connection 22, for example, thus has an inner contour 9 with only one outlet bore 31. This outlet bore 31 has a short cylindrical section, to which an axially parallel and also conically tapered section of the outlet bore 31 adjoins in order to generate a central, symmetrical and focused jet pattern.

[0062] Figure 9 shows a schematic sectional view of a cap-shaped

[0063] 1 shows an attachment body 8 for an injector 1 for injecting a gaseous medium according to a seventh exemplary embodiment. This exemplary embodiment is characterized in that a flow deflector 27 protrudes from the insert part 24 in the downstream direction. The flow deflector 27 can either be formed integrally with the insert part 24 or can be fastened to its interior, for example by welding. The flow deflector 27 is designed, for example, like a tappet and ends with a deflection geometry 28. The deflection geometry 28 is formed on a plate-shaped end section of the flow deflector 27. In the exemplary embodiment shown, the deflection geometry 28 extends 360°, with the deflection angle of the deflection geometry 28 being selected to be constant over the circumference.The flow emerging from the insert part 24 experiences a strongly radially outwardly directed component due to the impact on the deflection geometry 28 of the flow deflector 27 in order to produce a widely fanned-out jet pattern.

[0064] 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 an eighth exemplary embodiment. This solution is very similar to the exemplary embodiment shown in Figure 3. However, the insert part 24 is not fastened in the base body 23 via a screw connection 22 in the receiving opening 25; rather, the insert part 24 is secured in the receiving opening 25 of the base body 23 by means of several circumferentially engaging screws 33, which extend through transverse openings in the base body 23 and radially inward into threaded bores of the insert part 24.

[0065] Figure 11 shows a schematic sectional view of a cap-shaped attachment body 8 for an injector 1 for injecting a gaseous medium according to a ninth exemplary embodiment. As an alternative to the previously described screws 33, the insert part 24 is secured in the receiving opening 25 of the base body 23 by means of a snap ring 34 or another type of retaining ring, so that slipping of the insert part 24 relative to the base body 23 is prevented due to the axial fixation.

[0066] Figure 12 shows a schematic sectional view of a cap-shaped attachment body 8 for an injector 1 for injecting a gaseous medium according to a tenth embodiment. This solution differs only slightly from that according to Figure 9. This embodiment is again characterized by the fact that a flow deflector extends from the insert part 24 in the downstream direction.

[0067] 27 protrudes. The flow deflector 27 can either be formed in one piece with the insert part 24 or can be fastened to its interior, for example by welding. The flow deflector 27 is designed like a tappet and ends with the deflection geometry 28, which is formed on the plate-shaped end section of the flow deflector 27. In the illustrated embodiment, the deflection geometry 28 is designed to encircle 360°, with various deflection angles a 1 , a2 being provided. The deflection angles a 1 , a2 of the deflection geometry

[0068] 28 is not necessarily designed to be 180° in half. Rather, a variety of deflection angles a1, a2 can be provided over the circumference, allowing many different deflection segments to create a desired, specific spray pattern. The flow exiting the insert part 24 experiences a strongly radially outwardly directed component due to the impact on the deflection geometry 28 of the flow deflector 27, creating a widely fanned-out spray pattern.

[0069] Figure 13 shows a schematic sectional view of a cap-shaped attachment body 8 for an injector 1 for injecting a gaseous medium according to an eleventh exemplary embodiment, while Figure 14 shows a schematic bottom view of the attachment body 8 according to Figure 13. As an example of an uneven distribution of different deflection segments with specific deflection geometries 28 over the circumference of the flow deflector 27, Figures 13 and 14 show the variant of a non-circulating flow deflector 27. The flow deflector is, for example, only circularly formed over approximately 270°, while in order to generate an asymmetrical jet pattern, the tappet of the flow deflector 27 runs out axially parallel in a partial section of approximately 90° and therefore does not provide any flow deflection there at all.The size of the circumferential areas of the subsections of the plate-shaped end section of the flow deflector 27 as well as their deflection angles a1, a2 in the various deflection segments can be freely selected and combined with one another in an extremely wide variety of ways.

[0070] The deflection angle a1, a2 in the respective section can be selected between 0° and 85° (see Figure 13). The number of deflection segments of the flow deflector 27 should not exceed twelve. The smallest circumferential segment widths should not be less than 30°. Asymmetric design variants are particularly advantageous when the injector 1 is installed laterally on the cylinder head. This can significantly improve mixture formation; higher efficiency can be achieved; and combustion anomalies can be reduced.

[0071] The extensive customer variations (including jet angle, number of holes, projection of the attachment body 8 on the cylinder block, etc.) can be covered by a customized geometry of the insert part 24. This allows all customer-specific design variants to be manufactured cost-effectively and with less effort.

[0072] In addition, the proposed solutions will provide more flexible

[0073] This allows for hole designs that may be required, for example, in limited installation space. This provides increased freedom for various dimensions of cap-shaped attachment bodies 8, with the outer diameters of the attachment bodies 8 in the area of ​​attachment to the nozzle body 2 being, for example, in the range of 8 mm to 15 mm, while the outer diameters of the attachment bodies 8 in the area of ​​the outlet 19 are, for example, in the range of 6 mm to 12 mm.

Claims

Claims 1. Injector (1) for injecting a gaseous medium, in particular a gaseous fuel, preferably hydrogen, into a combustion chamber (20) of an internal combustion engine, comprising an axially movable valve closing element (5) for opening and closing at least one opening on a sealing seat (7), an actuator (21) for actuating the valve closing element (5), and a flow-influencing geometry (10) arranged downstream of the sealing seat (7), characterized in that the flow-influencing geometry (10) is integrated in a multi-part attachment body (8), wherein the attachment body (8) comprises a cap-like base body (23) which can be fastened to a nozzle body (2) of the injector (1), and the base body (23) has a receiving opening (25) into which an insert part (24) can be inserted and fastened there,wherein the insert part (24) contains the geometries responsible for the jet shaping with the outlet (19) of the attachment body (8)., 2. Injector according to claim 1, characterized in that the insert part (24) is an individual component which is manufactured separately from the base body (23) and is largely cylindrical.

3. Injector according to claim 1 or 2, characterized in that the receiving opening (25) of the base body (23) is designed such that the insert part (24) can be inserted with a precise fit from the downstream side of the base body (23).

4. Injector according to claim 3, characterized in that the insert part (24) is inserted into the receiving opening (25) of the base body (23) until it abuts against a stop shoulder of the base body (23).

5. Injector according to one of the preceding claims, characterized in that the insert part (24) and the base body (23) are firmly and securely connected to one another, in particular by means of a screw connection (22), in order to form the attachment body (8) as an overall structural unit.

6. Injector according to one of the preceding claims, characterized in that in the installed state, the insert part (24) with the outlet (19) projects beyond the lower end face of the base body (23) in order to take over the jet shaping.

7. Injector according to one of the preceding claims, characterized in that a jet splitter (26) serving as a flow rocker is provided on the insert part (24), which jet splitter projects from the insert part (24) into the base body (23) against the direction of flow.

8. Injector according to one of the preceding claims, characterized in that between one and ten outlet bores (31) are provided in the insert part (24), which extend in particular as oblique bores.

9. Injector according to one of the preceding claims, characterized in that a flow deflector (27) protrudes from the insert part (24) in the downstream direction, which flow deflector has a deflection geometry (28) which is either uniformly circumferential or has a plurality of deflection segments seen over the circumference.

10. Injector according to one of the preceding claims, characterized in that at maximum needle lift (lh) of the valve closing element (5) the following relationship applies: 5 x lh > s > 1.5 x lh, where (s) is the distance between the radially outer contour of the valve closing element (5) at its downstream edge region and the ring line lying axially below it in a projection on the section (12) of the flow influencing geometry (10) in the base body (23) of the attachment body (8) tapering in the flow direction, in order to generate a virtually loss-free flow downstream of the valve closing element (5).

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

12. Injector according to claim 10 or 11, characterized in that the section (12) of the flow-influencing geometry (10) tapering in the flow direction downstream of the valve closing element (5) is designed with an inclination angle a of 85° > a > 30°, preferably with an inclination angle a of > 45°.

13. Injector according to one of the preceding claims, characterized in that the valve closing element (5) is part of an axially movable valve needle, wherein the valve closing element (5) has an end section (6) which is largely plate-shaped.

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