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, among other things, 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).According to the invention, 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).

Description

Prior ArtThe 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. The invention relates in particular to an injector with which hydrogen can be injected directly into the combustion chamber of a mixture-compressing, spark-ignited internal combustion engine.Gas injectors are known from the prior art in different configurations. Because of cost advantages and improved environmental compatibility, gaseous fuels have become more popular recently. It is problematic here, in comparison with injectors for liquid fuels, that the quantity of gas to be injected takes up a much larger volume than an equivalent quantity of liquid fuel. This results in an increased stroke requirement of a closing element, which is usually actuated by a magnetic actuator. The design of the magnetic circuit using standard materials is very difficult or in some cases impossible because of the limited installation space. Materials with higher magnetic force are very expensive and in some cases harmful to health (e.g. FeCo).DE 10 2021 206 438 A1 already discloses a gas nozzle for a gas valve, which nozzle nozzle comprises a nozzle body which is at least partially hollow-cylindrical and forms a sealing seat via which a gas flow path leads. In addition, the gas valve has a valve closing element which is held in sections in the nozzle body and can move in a stroke manner, with an end section which is arranged outside the nozzle body and has a sealing contour which interacts with the sealing seat. In addition, the gas valve has a sleeve surrounding the nozzle body and the end section of the valve closing element, which sleeve delimits the gas flow path downstream of the sealing seat, wherein the gas flow path downstream of the sealing seat has a cross-sectional constriction for achieving the Venturi effect, in the region of which at least one intake duct opens. The sleeve is designed in the form of a blow cap which can be applied to the nozzle body.A further injector for blowing in a gaseous medium is likewise known from WO 2023 / 001384 A1. The blow cap which can be placed on a nozzle body has a sleeve-shaped base body with a circumferential lateral surface which merges at the downstream end into a base region. The base region is designed in such a way that at least one obliquely or asymmetrically blowing-off outlet opening is provided, wherein a flow guide section directed inwards towards the valve closing element counter to the flow direction is furthermore formed in the base region, said flow guide section carrying out a flow deflection of the gas to be blown out.Disclosure of the InventionThe injector according to the invention for blowing a gaseous medium, in particular a gaseous fuel, into a combustion chamber of an internal combustion engine, having the features of claim 1, has the advantage over the related art that an optimized gas flow in the injector is made possible by geometric design of a flow influencing geometry arranged downstream of the sealing seat, so that the internal flow of the gaseous medium is designed as lossless as possible via the inner contour of the cap-shaped attachment body, so that the dynamic 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.In addition, the forces acting on the valve closing element are reduced to a minimum in a particular manner. This reduces the magnetic force of an actuator, which must be selected to keep the injector open, and thus enables the use of cost-effective materials in the magnetic circuit of the actuator.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 and keep open the valve closing element by a stroke movement, while the valve closing element is closed by a spring force.The cap-shaped attachment body, which may also be referred to for short as a blow cap, has a particularly configured flow influencing geometry and is distinguished according to the invention in that the flow influencing geometry is integrated in a multipart 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 jet forming with the outlet of the attachment body.The multi-part nature of the attachment body advantageously offers very great flexibility in the beam design, since the beam guidance via the geometry of the insert part can be effected in a range of variations. With a reference injector or with few reference injectors, it is possible to test a plurality of design variants of the attachment body on a single-cylinder engine or on a multi-cylinder engine or in a jet chamber. In this way, a more rapid sampling of the various design variants is made possible. Replacement or dismantling of an insert part is possible at all times with great difficulty on the attachment bodies. Advantageously, only a few design variants are required for the base body of the attachment body, in order nevertheless to represent a very wide range of flow configuration via the diversity of variants of the insert parts. Above all, in the case of such a multipart solution according to the invention, very complex design variants can be easily implemented in terms of production technology.The dependent claims describe preferred developments of the invention.It is particularly advantageous to connect the insert part and the base body firmly and securely to one another. In this case, the insert part is fitted with an exact fit into a receiving opening of the base body of the attachment body and secured in particular by means of a screw connection, so that the attachment body is present as an overall structural unit.In an advantageous manner, in the installed state, the insert part with the outlet protrudes beyond the lower end face of the base body in order to assume the beam shaping alone.It is also advantageous if a beam splitter serving as a flow rocker is provided on the insert part, which beam splitter protrudes from the insert part counter to the flow direction into the base body, in order to be able to carry out a flow distribution in the attachment body at an early stage.In particular, it is advantageous if a flow diverter protrudes from the insert part in the downstream direction, which diverter has a deflection geometry which is either embodied in a uniformly encircling manner or has a plurality of deflection segments as seen over the circumference. Asymmetrical design variants are advantageous in particular when the injector is installed laterally on the cylinder head. In this way, the mixture formation can be significantly improved; a higher efficiency can be achieved; moreover, combustion anomalies can be reduced.A geometric configuration for the tapering first section is particularly advantageous if, at a maximum needle stroke I h of the valve closing element, the following relationship applies: 5×I h ≥s ≥1.5×I h, where s is the distance between the radially outer contour of the valve closing element at its downstream edge region and the ring line lying axially below it in a projection on a section of the flow influencing geometry tapering in the flow direction, in order to generate a virtually loss-free flow downstream of the valve closing element.It is particularly advantageous that the section of the flow influencing geometry tapering in the flow direction runs largely conically downstream of the valve closing element. It is advantageous here that the angle of inclination α of the inner contour in the region of the tapered section is 85°≥α≥ 30°, preferably is designed with a size of > 45°.This inner contour defined according to the invention can be advantageously accommodated with its special features in shape and design in attachment bodies with reducible external dimensions. This in turn allows a very flexible use of sleeves or attachment bodies on injectors in different combustion chamber geometries of internal combustion engines.The present invention is preferably used in injection systems directly injecting a combustion chamber. In particular, the injector is suitable for the direct injection of hydrogen into a combustion chamber of an internal combustion engine.DRAWINGPreferred embodiments of the invention will be described in detail below with reference to the accompanying drawings. In the drawing, the following is: FIG. 1 shows a schematic sectional view of an injector for injecting a gaseous medium according to the prior art, FIG. 2 is a sectional view of a known cap-shaped attachment body for an injector according to FIG. 1 , FIG. 3 shows a schematic sectional view of a cap-shaped attachment body for an injector for injecting a gaseous medium according to a first exemplary embodiment, FIG. 4 shows a schematic sectional view of a cap-shaped attachment body for an injector for injecting a gaseous medium according to a second exemplary embodiment, FIG. 5 shows a schematic sectional view of a cap-shaped attachment body for an injector for injecting a gaseous medium according to a third exemplary embodiment, FIG. 6 shows a schematic sectional view of a cap-shaped attachment body for an injector for injecting a gaseous medium according to a fourth exemplary embodiment, FIG. 7 shows a schematic sectional view of a cap-shaped attachment body for an injector for injecting a gaseous medium according to a fifth exemplary embodiment, FIG. 8 is a schematic sectional view of a cap-shaped attachment body for an injector for injecting a gaseous medium according to a sixth exemplary embodiment, FIG. 9 is a schematic sectional view of a cap-shaped cap body for an injector for injecting a gaseous medium according to a seventh exemplary embodiment, FIG. 10 shows a schematic sectional view of a cap-shaped attachment body for an injector for injecting a gaseous medium according to an eighth exemplary embodiment, FIG. 11 is a schematic sectional view of a cap-shaped cap body for an injector for injecting a gaseous medium according to a ninth exemplary embodiment, FIG. 12 is a schematic sectional view of a cap-shaped attachment body for an injector for injecting a gaseous medium according to a tenth exemplary embodiment, FIG. 13 is a schematic sectional view of a cap-shaped attachment body for an injector for injecting a gaseous medium according to an eleventh exemplary embodiment; and FIG. 14 shows a schematic bottom view of the attachment body according to FIG. 13.Preferred Embodiments of the InventionTo better understand the invention, the basic structure of an injector for blowing in a gaseous medium and a known structure of a flow influencing geometry downstream of the valve seat in terms of flow technology are described below with reference to FIGS. 1 and 2.FIG. 1 schematically shows a sectional view 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, only this assembly is described in more detail here, even in the case of the known injector 1. For actuating the injector 1, a magnetic actuator 21 is provided, for example, so that the injector 1 can be controlled in a targeted manner by this means.The injector 1 also has a nozzle body 2 which, on the injection side, forms, on the end side, a valve seat 3, which is shaped, for example, conically, for a valve closing element 5 which opens outwards, that is to say opens in the direction of 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, corresponding to the valve seat 3, forms a sealing seat 7. The two sealing seat partners valve seat 3 and valve closing element 5 are each metallic. The geometric and material design is effected in such a way that sufficient tightness is ensured during operation of a hydrogen engine. In the event of a fault, a shut-off system, which is fluidically connected upstream of the injector 1 for safety reasons and is not shown here, would ensure an interruption of the supply of the gaseous medium, in particular of the readily 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 conicity. However, other contours are also conceivable.The nozzle body 2 and the end section 6 of the valve closing element 5 are surrounded by a sleeve 8 for jet forming. In the following, in particular also with respect 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 be formed directly as one piece on the nozzle body 2, which however requires a high manufacturing effort, or integrated in an additional component, wherein this component is generally referred to as sleeve 8 in relation to the embodiments according to the prior art in FIGS. 1 and 2. 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, it is also possible to refer to a cap-shaped attachment body 8, which is also defined as a blow cap 8 with respect to the exemplary embodiments according to the invention.The sleeve 8 and the end section 6 of the valve closing element 5 together delimit a gas flow path 4, into which at least one intake duct 15 formed in the sleeve 8 opens. Air can be sucked from the environment into the gas flow path 4 via the one or more suction channels 15.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 space 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 following the valve closing element 5 in the flow direction, 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 influencing geometry 10 of the sleeve 8, wherein the tapering is achieved via a conically extending section 12 in the inner contour 9 of the sleeve 8. The suction ducts 15 open exactly in the central axial region 13 into the inner contour 9 of the sleeve 8.The reduction in cross section within the gas flow path 4 provides the effect that, when the gas flows out via the gas flow path 4 in the direction of an outlet 19, air is drawn from the environment into the gas flow path 4 via the intake ducts 15 ("Venturi effect"). This means that air is added to the gas even before it reaches the outlet 19, so that the mixture preparation is improved in this way.The reduction in cross section is canceled again in that the central axial region 13 is again followed by a conically running section 14, but in this case widening conically in the direction of flow, this section 14 extending as far as the outlet 19. The cross-sectional reduction in the inner contour 9 of the sleeve 8 is provided in this respect for achieving the Venturi effect which is optimized together with the air admixture. 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 optimum combustion.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 in terms of flow, with which optimum combustion results are achieved on the basis of the flow guidance according to the invention.Injection systems for the direct injection of a gaseous medium, in particular of hydrogen, but also CNG, methane, ammonia or mixtures of the aforementioned gases have the task of specifically controlling the metering and also the injection direction of the gas jet or the gas jets into the combustion chamber 20 via injection valves or generally 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 (hydrogen) direct injection have, on principle, a large lift requirement of the valve needle with the valve closing element 5. Materials with higher magnetic force and thus better B / H characteristics are very expensive and in part also harmful to health (e.g. FeCo). In this respect, a magnetic force reduction is also intended to be achieved by means of an improved beam guidance.The core of the invention consists in configuring the internal flow of the gaseous medium as free of losses as possible via the inner contour 9 of the cap-shaped attachment body 8 according to the invention, so that the dynamic 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 can be accommodated with its special features in shape and design in an advantageous manner in attachment bodies 8 with reducible external dimensions. This in turn allows a very flexible use of sleeves or attachment bodies 8 on injectors 1 in different combustion chamber geometries of internal combustion engines.Below, with reference to FIGS. 3 to 14, injectors 1 with attachment bodies 8 according to the invention with flow influencing geometries 10 according to preferred exemplary embodiments of the invention arranged downstream of the valve seat 3 in terms of flow are described in detail. According to the invention, the cap-shaped attachment body 8 is embodied in multiple parts. The attachment body 8 will usually have a significantly shorter overlap length with the nozzle body 2 than shown in FIG. 1. What is important is merely a secure and reliable fastening to the nozzle body 2, which enables a perfect and axis-parallel alignment with respect to the injector 1. Known joining methods such as pressing, welding, soldering, adhesive bonding or combinations thereof can be used.FIG. 3 shows a first exemplary embodiment of a flow influencing geometry 10 arranged downstream of the valve seat 3 in terms of flow in a cap-shaped attachment body 8 and produced via an inner contour 9 according to the invention. The valve closing element 5 with its plate-shaped end section 6 is only shown schematically and simplified. However, the end section 6 can also have bevels or rounded-off areas on its outer contour.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 main body 23 of the attachment body 8 merges with its inner contour 9 into a receiving opening 25, into which an insert part 24 can be inserted and fastened there. The insert part 24 is a compact, separately manufactured and largely cylindrical individual component which contains the geometries responsible for the beam forming as far as the outlet 19 of the attachment body 8. The receiving opening 25 of the base body 23 is designed in such a way that the insert part 24 can be introduced with an exact fit from the downstream side of the base body 23. As shown in FIG. 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 connecting technology, it is possible to replace the insert 24 with another insert by releasing the screw connection 22.The insert part 24 is introduced, for example, so deeply into the receiving opening 25 of the base body 23 until it abuts against a stop shoulder of the base body 23. In the installed state, the insert part 24 can protrude with the outlet 19 beyond the lower end face of the base body 23, so that, with regard to the beam forming, the geometry of the inner contour 9 of the insert part 24 alone is responsible and there is no influence by the outer contour of the base body 23.In the first exemplary embodiment of a cap body 8 shown in FIG. 3, the insert part 24 has an inner contour 9, which first has a trough-like inlet region 30, from which a plurality of 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, but also run axially parallel. Ideally, between two and ten outlet bores 31 are provided in order to achieve a homogeneous jet distribution.In addition to the flow influencing geometry 10 introduced in the insert part 24 via the inner contour 9, the base body 23 upstream of the insert part 24 also already has a plurality of interesting aspects and geometry specifications, wherein the ratio of two surfaces to one another is considered as an essential criterion, namely the two surfaces A S and A 1 which result at a maximum valve needle stroke I h, i.e. at a maximum open sealing seat 7 and thus at a maximum lifted valve closing element 5. The surface A S represents the annular seat cross-sectional surface which results between the valve seat 3 and the contact line of the end section 6 of the valve closing element 5, while the surface A 1 is determined by the distance which results as the shortest distance between the outer contour of the valve closing element 5 at its downstream edge region and the opposite wall of the inner contour 9. In other words, the surface A 1 forms the narrowest cross section below the valve closing element 5 when the sealing seat 7 is open to the maximum. This surface A 1 also extends annularly and is located as an imaginary surface, here at approximately right angles, on a tapering, in particular conically extending, section 12 in the inner contour 9 of the attachment body 8, which section ensures a distinct tapering of the inner contour 9 over a short axial extent, which likewise advantageously contributes to the desired optimized flow result. The following should apply to the ratio of the areas A S and A 1: A 1 ≥2.5×A S.The jet guidance coming from the sealing seat 7 is effected via the inner contour 9 in the conically running section 12 which is designed with an angle of inclination α of 85° ≥ α ≥ 30°, preferably with an angle of inclination α of > 45°. With this rather large angle α of the conically extending section 12, a strong radially inwardly directed flow component is generated over a very short axial extension length. The lines of the flow path 4 illustrate this.A further characteristic variable of the configuration of the inner contour 9 is the distance s which results at a maximum needle stroke I h 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 conically running section 12. The following should apply here: 5×I h ≥s≥1.5×I h, 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×I h ≥s≥2.5×I h. applies. The maximum needle stroke I h extends over an axial extension length of 100 μm to 2 mm, wherein the maximum needle stroke I h will ideally lie between 0.15 mm and 0.5 mm.As a result of these geometric requirements, a flow diversion from a large diameter in the region of the sealing seat 7 to a significantly smaller diameter with an inner surface A 2 at the end of the tapering, in particular conically extending section 12 takes place over a short axial path length in the region of the valve closing element 5, so that a flow diversion takes place in an advantageous manner in the form of an "S-stroke" in this region directly downstream of the valve closing element 5. Instead of the conical profile of the section 12, this section 12 can also be slightly convexly curved or slightly concavely curved. In addition to the ratio of the flow cross sections corresponding to A 1 ≥2.5×A S the following should therefore also additionally apply for the flow cross sections of the surfaces A S and A 2: 5×A S ≥A 2 ≥2×A S, so that supercritical flow is ensured and a limitation of ram pressures below the valve closing element 5 is achieved.Also associated with this is the acceleration of the flow in the direction of the insert part 24, which is marked with the axial region 13 following the conically running section 12 in the flow direction, with reduction of the losses or turbulences in the wall region and an approach of the effective flow cross section to the geometric cross-sectional area A 2. The axial region 13 is ideally a cylindrical hole section which merges directly into the receiving opening 25. While the first conically extending 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 producing a high jet stability. In addition, a reduction of the losses or turbulences at the wall area is achieved, wherein overall an approximately effective filling of the flow cross section in the cylindrical axial area 13 is made possible. The smallest possible bore diameter in the axial region 13 contributes to the reduction of the dead volume.FIG. 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 in turn fastened in the base body 23 by means of a screw connection 22, for example, has an inner contour 9 with a single outlet bore 31. This outlet bore 31 has a short cylindrical section, which is adjoined by a section of the outlet bore 31 which tapers obliquely and still conically in relation thereto, in order to produce an asymmetric single-sided jet pattern.FIG. 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 oblique bores. The particular solution shown in FIG. 3 is a beam splitter 26 serving as a flow rocker or as a spoiler, which, as illustrated, may taper to a large extent to a point or may also be formed with a small plateau. Alternatively, the beam splitter 26 can also be rounded. The beam splitter 26 protrudes from the insert part 24 counter to the flow direction into the axial region 13 and possibly also into the conically extending section 12 of the base body 23, so that a flow distribution can be carried out early in the attachment body 8. For the fixed connection of the insert part 24 and the base body 23, a screw connection 22 is again provided.FIG. 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 oblique bores, but in this case have an orientation converging radially inward toward the central axis. The beam splitter 26 serving as a flow rocker or as a spoiler has a plateau of larger area, from which flow guidance to the outlet bores 31 can take place at the beam splitter 26. Alternatively, the beam splitter 26 can also be rounded. The beam splitter 26 protrudes from the insert part 24 counter to the flow direction into the axial region 13 and possibly also into the conically extending section 12 of the base body 23, so that a flow distribution can be carried out early in the attachment body 8. For the fixed connection of the insert part 24 and the base body 23, a screw connection 22 is again provided.FIG. 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 embodiment shown in FIG. 4. The insert part 24, which is in turn 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, which is adjoined on the one hand by a section of the first outlet bore 31 which tapers obliquely and still conically thereto and on the other hand by a section of the second outlet bore 31 which is aligned largely axially parallel and also tapers conically, for example, in order to produce an asymmetric jet pattern.FIG. 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, which is adjoined by an axially parallel, and still conically tapering section of the outlet bore 31 in order to generate a central symmetrical and focused beam image.FIG. 9 shows a schematic sectional view of a cap-shaped attachment body 8 for an injector 1 for injecting a gaseous medium according to a seventh exemplary embodiment. This exemplary embodiment is distinguished in that a flow diverter 27 protrudes from the insert part 24 in the downstream direction. The flow diverter 27 can either be formed integrally with the insert part 24 or else be fastened in its interior, for example by welding. The flow diverter 27 is designed, for example, in the manner of a plunger and ends with a deflection geometry 28. In the exemplary embodiment shown, the deflection geometry 28 is configured so as to be 360° encircling, wherein the deflection angle of the deflection geometry 28 is selected to be constant over the circumference. The flow emerging from the insert part 24 experiences a component directed strongly radially outwards as a result of the impact on the deflection geometry 28 of the flow deflector 27, in order to generate a far-fanned beam pattern.FIG. 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 embodiment shown in FIG. 3. However, the fastening of the insert part 24 in the base body 23 does not take place via a screw connection 22 in the receiving opening 25; rather, the securing of the insert part 24 in the receiving opening 25 of the base body 23 takes place by means of a plurality of screws 33 which engage circumferentially and extend through transversely running openings in the base body 23 and radially inward as far as into threaded holes of the insert part 24.FIG. 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 screws 33 described above, the insertion part 24 is now secured in the receiving opening 25 of the base body 23 by means of a snap ring 34 or another type of securing ring, so that, due to the axial fixing, slipping of the insertion part 24 relative to the base body 23 is prevented.FIG. 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 exemplary embodiment. This solution differs only slightly from that according to FIG. 9, which is again distinguished in that a flow diverter 27 protrudes from the insert part 24 in the downstream direction. The flow diverter 27 can either be formed integrally with the insert part 24 or else be fastened in its interior, for example by welding. The flow diverter 27 is designed like a plunger and ends with the diverting geometry 28, which is formed on the plate-shaped end section of the flow diverter 27. In the exemplary embodiment shown, the deflection geometry 28 is configured so as to extend through 360°, wherein different deflection angles α 1, α 2 are provided. In this case, the deflection angles α 1, α 2 of the deflection geometry 28 are not necessarily configured half way over 180° in each case. Rather, a plurality of deflection angles α1, α2,... may be provided over the circumference, so that many different deflection segments can provide a desired specific beam image structure. The flow emerging from the insert part 24 experiences a component directed strongly radially outwards as a result of the impact on the deflection geometry 28 of the flow deflector 27, in order to generate a far-fanned beam pattern.FIG. 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 FIG. 14 shows a schematic bottom view of the attachment body 8 according to FIG. 13. As an example of an unequal distribution of different deflection segments with specific deflection geometries 28 over the circumference of the flow deflector 27, FIGS. 13 and 14 show the variant of a non-revolving flow deflector 27. The size of the circumferential regions of the partial sections of the plate-shaped end section of the flow diverter 27 and their deflection angles α1, α2,... in the various deflection segments can be freely selected and combined with one another in an extremely variable manner.The deflection angle α 1, α 2,... in the respective subsection can be selected between 0° and 85° (see FIG. 13 ). The number of baffle segments of the flow diverter 27 should not exceed twelve. Smallest circumferential segment widths should not fall below 30°. Asymmetrical design variants are advantageous in particular when the injector 1 is installed laterally on the cylinder head. In this way, the mixture formation can be significantly improved; a higher efficiency can be achieved; moreover, combustion anomalies can be reduced.The extensive customer variants (among other things, jet angle, number of holes, excess dimension of the attachment body 8 on the cylinder block, etc.) can be covered by a customer-specific geometry of the insert part 24. All customer-specific design variants can thus be produced cost-effectively and with less effort.Furthermore, the proposed solutions achieve more flexible configurations of hole designs, which may be required, for example, in the case of a limited installation space. Thus, increased degrees of freedom are possible for different dimensions of cap-shaped attachment bodies 8, wherein the outer diameters of the attachment bodies 8 in the region of the attachment to the nozzle body 2 are, for example, in the range of 8 mm to 15 mm, while the outer diameters of the attachment bodies 8 in the region of the outlet 19 are, for example, in the range of 6 mm to 12 mm.References included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedDE 10 2021 206 438 A1

[0003] WO 2023 / 001384 A1

[0004]

Claims

Injector (1) for blowing 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 at a sealing seat (7), an actuator (21) for actuating the valve closing element (5), and a flow influencing geometry (10), which is fluidically arranged downstream of the sealing seat (7), characterized in that the flow influencing geometry (10) is integrated in a multipart attachment body (8), wherein the attachment body (8) comprises a cap-like basic body (23), which can be fastened to a nozzle body (2) of the injector (1), and the basic 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 beam forming with the outlet (19) of the attachment body (8).Injector according to Claim 1, characterized in that the insert part (24) is an individual component which is produced separately from the base body (23) and is largely cylindrical.Injector according to Claim 1 or 2, characterized in that the receiving opening (25) of the base body (23) is designed in such a way that the insert part (24) can be introduced with an exact fit from the downstream side of the base body (23).Injector according to Claim 3, characterized in that the insert part (24) is introduced into the receiving opening (25) of the base body (23), except for abutment on an abutment shoulder of the base body (23).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.Injector according to one of the preceding claims, characterized in that, in the installed state, the insert part (24) projects with the outlet (19) beyond the lower end face of the base body (23), in order to take over the beam shaping.Injector according to one of the preceding claims, characterized in that a beam splitter (26) serving as a flow rocker is provided on the insert part (24), said beam splitter protruding, starting from the insert part (24), counter to the flow direction into the base body (23).Injector according to one of the preceding claims, characterized in that the insert part (24) is provided between one and ten outlet bores (31), which extend in particular as oblique bores.Injector according to one of the preceding claims, characterized in that a flow diverter (27) projects from the insert part (24) in the downstream direction, said flow diverter having a deflection geometry (28) which is either of uniformly circumferential design or has a plurality of deflection segments as seen over the circumference.Injector according to one of the preceding claims, characterized in that, at a maximum needle stroke (I h) of the valve closing element (5), the following relationship applies: 5 × I h ≥ s ≥ 1.5 × I h, wherein (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 in a projection on the section (12), tapering in the flow direction, of the flow influencing geometry (10) in the main body (23) of the attachment body (8), in order to generate a virtually loss-free flow downstream of the valve closing element (5).Injector according to Claim 10, characterized in that, at a maximum valve needle stroke (I h) an annular seat cross-sectional area (A S) is produced between a valve seat (3) and the contact line of the valve closing element (5), and a further annular area (A 1) is determined by the distance which is produced as the shortest path 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) which narrows in the direction of flow, wherein the following applies to the ratio of the areas (A S and A 1): A 1 ≥ 2.5 × A S.Injector according to Claim 10 or 11, characterized in that the section (12) of the flow influencing geometry (10), which section narrows in the flow direction, downstream of the valve closing element (5) is designed with an angle of inclination α of 85° ≥ α ≥ 30°, preferably with an angle of inclination α of > 45°.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 in the form of a disk.

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