Fuel injector, in particular for atomizing methanol, associated machine, method and uses

Abstract

In order to efficiently atomize liquid fuels, such as methanol or ethanol, at low pressures of less than 100 bar, an injector (1) is proposed that has a static impact body (11) on which a homogeneous fluid jet of fuel generated by means of an injection nozzle (2) of the injector (1) can be atomized into microscopic droplets. In the process, the fluid jet emerging from a nozzle outlet opening (3) of the injection nozzle (2) of the injector (1) falls, preferably at comparably large angles of incidence of at least 60°, onto an atomization surface (15) which is formed by the impact body (11), as a result of which high shear forces and therefore an efficient atomization can be achieved.

Description

[0001] Fuel injector, in particular for atomizing methanol, and associated machine, process and uses

[0002] The invention relates to a fuel injector, or injector for short, which is intended and designed for atomizing and / or injecting a liquid fuel. This injector comprises: an injection nozzle having a nozzle outlet opening, from which a homogeneous fluid jet of fuel can emerge in a straight line along an outflow direction (in contrast to swirl nozzles); and a nozzle valve with which a flow of fuel through the injection nozzle of the injector can be released. If the nozzle valve is opened, the fuel can flow through the injection nozzle and exit from the nozzle outlet opening. The nozzle valve can be permanently pressurized with fuel on the inlet side during operation. The amount of fuel briefly delivered by the fuel injector (more precisely: by the injection nozzle) can be set / specified, for example, by the duration for which the nozzle valve is opened.

[0003] The invention further relates to an internal combustion engine with at least one combustion chamber, an intake manifold positioned upstream of the respective combustion chamber (in the direction of fuel flow), and at least one intake valve with which the flow of a fuel-air mixture from the intake manifold into a / the combustion chamber can be controlled. Finally, the invention also relates to a method for operating such an internal combustion engine and specific uses of an injector according to the invention, namely for atomizing liquid fuels with a low flash point, such as methanol.

[0004] Numerous fuel injection systems are already known in the prior art, allowing liquid fuels to be finely atomized to create a combustible fuel-air mixture, which can then be ignited in a combustion chamber / cylinder of an internal combustion engine to power the engine. In addition to diesel as a conventional fuel, other fuels such as methanol are increasingly being used. Depending on the application, methanol, for example, should be injected in addition to diesel fuel in a sufficiently fine atomization to enable operation with both fuels, especially simultaneously.

[0005] A further technical boundary condition on which the present invention is based is that in many applications, for example in maritime applications, the available pressure with which the fuel can be supplied to the injector is limited to < 100 bar (= low pressure range) or even to < 20 bar.

[0006] Based on this technical background, the object of the invention is to provide an injector with which new types of fuel, such as methanol or ethanol, to name just two examples, can be atomized very finely and with fast switching times of the injector in the low pressure range (< 100 bar) into a fuel mist consisting of very fine droplets, for example with a typical average (temperature-dependent) droplet size in the range of approx. [ 200 . . 400 ] pm. The aim is to achieve the desired microscopic droplet size and thus a high degree of atomization of the fuel mist generated by the injector in a reliable and reproducible manner, in order to ensure high combustion efficiency and also to have a positive influence on the resulting exhaust gases.

[0007] To achieve this object, the invention provides a

[0008] A fuel injector which can be used in particular for injecting fuel into a desired area of ​​an internal combustion engine is provided, having the features of claim 1. In particular, to achieve the object with an injector of the type mentioned at the outset, the invention proposes that the injector comprise a freely suspended impact body which follows the nozzle outlet opening in the outflow direction and forms an atomization surface aligned obliquely to the outflow direction for atomizing the fuel. The atomization surface can preferably be designed to be rotationally symmetrical.

[0009] According to the invention, the impact body can thus be designed as a separate component and held freely suspended above the nozzle outlet opening by means of its own suspension (so that the impact body is not manufactured in one piece from the same material as the suspension). In particular, the impact body can be designed as a turned metal part (turned part produced by turning) and / or connected to the separate suspension by means of a connection, in particular a form-fitting and / or material-fitting connection, which holds the impact body in position above the nozzle outlet opening.

[0010] The said suspension can be designed in the form of a single-legged or multi-legged bridge, as will be described in more detail below. By designing the suspension and impact body separately, the necessary precision in shaping the atomization surface of the impact body can be achieved in order to ensure the most homogeneous distribution of the fuel droplet size within the spray jet generated by the injector. In addition, while retaining the suspension, the impact body can be replaced more easily, for example in order to easily manufacture several injector variants with different spray angles. The connection between the suspension and impact body can preferably be designed so that the impact body is replaceable (for example during repair / maintenance of the injector).

[0011] Such an injector according to the invention, which is preferably configured as a single-jet so that it produces a homogeneous (single-jet and preferably rotationally symmetrical) spray jet of finely atomized microscopic fuel droplets, can preferably be used to atomize fuels with high surface tension, such as methanol or ethanol, at pressures of less than 100 bar. The injector is preferably installed in an internal combustion engine (in particular according to claim 16) in such a way that the single-piece spray jet of the injector is assigned exclusively to a single inlet opening in a combustion chamber of the internal combustion engine (so that the entire spray jet of fine droplets reaches this inlet opening).

[0012] This injector is particularly suitable for maritime applications and / or for use in large industrial engines. The finest possible fuel atomization is important to ensure high efficiency, thus low fuel consumption, and optimal combustion, which can improve exhaust emissions.

[0013] By designing the injector in this way it can be achieved in particular that the entire fluid jet emerging from the nozzle outlet opening, after traversing a free path in air, strikes the atomizing surface of the impact body and is atomized there into (typically microscopic) droplets, whereby the desired spray jet is generated. Therefore, the atomizing surface could also be referred to or understood as an impact surface, since the fluid jet bounces off the atomizing surface and is thus deflected from the original outflow direction. In this case the deflection for individual radial components of the fluid jet can also be designed to varying degrees, depending on the outer contour of the impact body, as will be explained in more detail below (i.e. particularly when the atomizing surface has different orientations to the outflow direction).The atomization surface can be understood here as that portion of the surface of the impact body onto which the fluid jet would impinge if it were to propagate in a straight line from the nozzle outlet opening.

[0014] After the fluid jet of fuel has been atomized on the atomization surface, the resulting fuel droplets can move in the outflow direction beyond the impact body as a spray jet of fine fuel mist. The jet of fine fuel droplets generated by the injector can have a full opening angle (so-called "spray angle") of typically 20° to 90° or even more, depending on the dimensions and design of the injection nozzle and impact body and on the pressure, temperature and (air) counterflow used. The spray angle will generally be somewhat larger than the opening angle assumed by the impact body: at typical operating pressures of < 20 bar, around 8 bar, for example, a spray angle of 35° can result when using an impact body with a 30° opening angle.For higher fuel pressures, the difference between the spray angle and the impact body will increase. In addition to the operating pressure on the inlet side of the nozzle valve, the temperature, the type of fuel, and the (air) counterflow acting on the fuel during atomization (for example, in an intake manifold) also influence the formation of the spray angle. Therefore, tests and / or simulations will typically be necessary to define an optimal impact body shape for a desired spray angle.

[0015] With such an injector, it is possible to achieve a high degree of atomization, i.e., to create the finest possible droplets of fuel dissolved in air. This is advantageous, for example, when the injector is used to inject fuel into the intake manifold of a large engine. This is especially true when methanol is injected with the fuel injector. The fundamental challenge with methanol, in particular, is that methanol has a high enthalpy, so a strong cooling effect occurs during atomization, which is precisely what is unfavorable for promoting the solubility of methanol in air.By using the impact body according to the invention, which the fluid jet already encounters in the air environment and which is preferably subsequently kept largely free of limiting components (as will be explained in more detail below), the injector can generate a finely atomized fuel mist, which can be released from the impact body almost unhindered in a certain radiation cone (the full opening angle of this "spray angle" of the fuel mist can be between 20° and 90° or even more depending on the specific design) into the space (e.g. the aforementioned intake manifold).

[0016] A second effect, which is overcome by means of the impact body according to the invention, is that high shear forces or a high energy must be used to tear open the methanol fluid at its surface in order to initiate droplet formation / atomization in the first place. It must be taken into account that methanol, for example, has a higher surface tension than diesel fuel. With the impact body, such shear forces can be achieved at a sufficient level. The inventive concept of using a free-floating element following the outlet opening by means of a (preferably designed separately from the impact body)

[0017] The suspension of the impact body thus makes it possible, in particular, to achieve sufficient atomization of methanol when the fluid pressure at the injector is less than 20 bar. This is particularly relevant for maritime applications, where the engines in which the fuel injector can be used are operated, for safety reasons, with low pressures of typically no more than 10-12 bar in the fuel supply lines. With a fuel injector according to the invention, it is also possible to serve the typically very large cross-sections of the cylinders of ship engines.

[0018] According to the invention, the object can also be achieved by further advantageous embodiments, as defined in the subclaims and explained in detail below:

[0019] Thus, it is advantageous for efficient atomization of the fuel if the atomization surface is arranged within an imaginary circular cone, the tip of which points towards the nozzle outlet opening and whose full opening angle is 2 <p höchstens 130 ° beträgt . Für bestimmte Anwendungen, die geringe Sprühwinkel erfordern, kann es aber vorteilhaft sein, wenn der volle Öf fnungswinkel 2<p höchstens 60 ° , höchstens 45 ° oder sogar nur höchstens 35 ° beträgt . Für einen Prallpin in Form eines geraden Kreiskegels mit Durchmesser D=2r und Höhe H ergibt sich der volle Öf fnungswinkel beispielsweise zu : 2<p = 2 arcsin [ r / H] = 2 arcsin [ D / 2H] .

[0020] As will be explained in more detail, such a shape promotes the generation of high shear forces within the fluid jet and thus efficient and fine atomization of the fuel, even at low fluid pressures. If the full aperture angle of the imaginary circular cone that defines the atomization surface is, for example, 2 x 30° = 60°, and the impact body is designed as a circular cone with a rotationally symmetrical atomization surface, it can be ensured, for example, that the angle of incidence θ at which the fluid jet strikes the atomization surface is always at least 90° - 30° = 60°. If the aperture angle is selected to be even smaller, correspondingly larger angles of incidence θ result.

[0021] With such a design, the impact body can thus exhibit a shape that increases in cross-section with increasing distance from the nozzle outlet opening, but is comparatively slender or elongated transversely to the outflow direction. For example, such features can be achieved with a slender conical shape of the impact body, but different shapes, particularly non-rotationally symmetrical shapes, are also possible. For example, the atomization surface can also be curved or designed with "dents" and / or edges.

[0022] It should also be noted that the opening angle of the jet cone of fine droplets emanating from the impact body (often referred to as spray angle or fan-out angle) will usually be somewhat larger than the

[0023] Opening angle of the imaginary cone within which the impact body is located. By appropriately shaping the impact body, the spray angle can thus be precisely adjusted depending on the application requirements. However, maintaining a comparatively small opening angle for the impact body is beneficial to enable efficient atomization. Furthermore, it is advantageous for efficient atomization if a maximum diameter D3, which the atomization surface fills in a radial plane running perpendicular to the outflow direction, is selected to be at least large enough so that the following applies: D3 > 0.50 Dl, preferably D3 > 0.85 Dl or particularly preferably D3 > 0.90 Dl or even D3 > Dl, where Dl is the diameter of the nozzle outlet opening. In individual cases, D3 can therefore be selected to be at least 10% larger than Dl.Such designs can, in particular, ensure that even the radially outermost parts of the fluid jet (i.e., the areas of the fluid jet cross-section farthest from the axis) can still impinge on the atomization surface. However, if the diameter D3 is < 0.8 Dl (approximately: D3 = 3.1 mm and Dl = 2.5 mm), efficient atomization is generally no longer achieved for all fuels; however, depending on the fuel, even lower values ​​can still lead to usable results.

[0024] A further preferred embodiment provides that the impact body is suspended by means of the aforementioned suspension such that an extension (in the direction of the outflow direction) of its atomization surface, which is oriented obliquely to the outflow direction, is kept clear within a specific angular range, specifically relative to an angle that extends around the outflow direction in a radial plane running perpendicular to the outflow direction. The kept clear angular range can be at least 150° or at least 180°, but preferably at least 240° or even at least 300°. Such features can ensure that fuel atomized on the impact body, which continues to fly obliquely to the original outflow direction, can escape from the injector unhindered in the kept clear angular ranges and thus without contact with components of the fuel injector.If, for example, the impact body is suspended from a bridge with only two legs, a two-part spray jet may initially be created (which, however, later merges back into a single jet). For example, if the discharge direction is interpreted as the z-axis in a Cartesian coordinate system, the angle circumscribing the z-axis thus runs in the xy-plane (as a radial plane perpendicular to the discharge direction).

[0025] Additionally or alternatively, it can also be provided that the impact body is suspended by means of the suspension in such a way that a radial plane running perpendicular to the outflow direction, which lies in the region of the front end of the impact body, is kept completely clear with the exception of the suspension. This is particularly advantageous because in this way, a gas from the environment (air or exhaust air or a mixture of both) can only come into contact with the resulting spray jet in this area, so that efficient atomization of the fuel based on shear forces (turbulence) can take place beforehand without disruption.

[0026] Such a design in particular prevents the fine fuel droplets formed on the impact body from excessively depositing on subsequent structures as soon as they extend beyond the impact body in the direction of flow or at an angle to it. In the case of injection nozzles which have a comparatively narrow and completely circumferential nozzle opening from which a fluid jet which has already been atomised on an impact body still has to emerge, it has been observed that in a design of this type there is a tendency for already atomised fuel to deposit on the inner walls of the injection nozzle. In this case, however, the droplets recombine so that the desired small droplet size and thus a high degree of atomisation can no longer be achieved. The design described above largely avoids such deposits of already atomised fuel.Because apart from a thin bridge on which the impact body is suspended / mounted / formed, the entire jet of finely atomized fuel emanating from the impact body can be ejected from the injector without the droplets coming into contact with other elements of the injector.

[0027] A preferred embodiment even proposes that not only the extension of the atomization surface in the direction of the fuel flow, but rather an imaginary second circular cone emanating from the tip of the impact body, is kept free (i.e. at least partially) in the angular ranges mentioned. The full opening angle of this second imaginary circular cone is selected to be at least 20°, preferably 40°, larger than the full opening angle of a first imaginary circular cone within which the impact body is located / which delimits the impact body.

[0028] To put it simply, in such cases only a necessary bridge or web on which the impact body is suspended casts a shadow on the jet of fine droplets emanating from the impact body, but otherwise the jet of fine droplets created at the impact body can spread out into the room unhindered without further contact with the injector, so that the small droplet size produced is maintained.

[0029] Depending on the application, such designs can, for example, ensure that a radiation cone emanating from the impact body can spread out on fine droplets of the fuel with a full opening angle between 40 ° and 90 ° (depending on the design) in the cleared angle areas without wall deposits (i.e. precipitation on the injector).

[0030] In order to generate a homogeneous fluid jet, it is further proposed that an outlet channel opening into the nozzle outlet opening be kept clear at its outlet-side end (i.e. in the region of the nozzle outlet opening), but preferably completely clear along its entire axial length. In this case, the fluid jet emerging from the nozzle outlet opening can, for example, have a circular disk-shaped cross-section. Non-circular disk-shaped cross-sections are of course also possible; however, it is preferred that a cross-section of the fluid jet forms a continuous surface without a hole, which is possible with the said design.

[0031] For example, the impact body can be suspended on one leg / one side above the nozzle outlet. In this case, the suspension should be solid to prevent unwanted vibrations of the impact body during injector operation.

[0032] A preferred embodiment provides that the impact body is suspended freely above the nozzle outlet opening by means of a bridge. This bridge can be designed, for example, as a thin web supported on one or both sides. The bridge can, for example, have two legs with which the bridge is supported on the injector, in particular on the injection nozzle, to the left and right of the impact body.

[0033] However, a preferred embodiment provides for said bridge to have three legs, with which it is supported on the injector, in particular on the injection nozzle. In particular, if the jet emerging from the nozzle outlet does not strike the impact body perfectly centrally, but rather slightly obliquely, vibrations of the impact body may occur, which have an adverse effect on the formation of the spray mist consisting of fine fuel droplets.At first glance, a three-legged bridge design has the disadvantage that, compared to a two-legged design, the angle range maintained free (with the same leg dimensions) must be smaller. However, a three-legged design offers the significant advantage that the bridge, and thus the impact body, is less prone to vibration when the fluid jet strikes the impact body, because the three legs can better absorb the transverse forces acting on the impact body. Preferably, the three legs could be arranged evenly distributed along the circumference (e.g., every 120°).

[0034] The impact body can also have a rounded tip near the nozzle. This prevents the tip of the impact body from deforming during operation and subsequently disrupting the spray pattern / atomization.

[0035] In order to avoid unnecessary diverging of the fluid jet before it hits the atomizing surface of the impact body, one embodiment provides that a free axial distance LI along the outflow direction between a nozzle-side tip of the impact body and the nozzle outlet opening is selected so small that:

[0036] LI < 1.75 Dl (approximately: LI = 5 mm and Dl = 3.1 mm), or LI < 1.50 Dl or even LI < Dl, where Dl is the diameter of the nozzle outlet opening. Such dimensioning can ensure that the fluid jet, after traversing a comparatively short distance in air, still hits the impact body in a homogeneous form. With a nozzle outlet diameter of 3.1 mm, for example, axial distances LI in the range of [2.0 - 2.6] mm are preferred. Accordingly, the following can preferably apply: 0.6 < Ll / Dl < 0.9. The exact values ​​for LI depend in particular on the operating pressure of the fuel used and can be optimized through testing.

[0037] Depending on the design, the distance LI can also be zero or even take on negative values. In the latter case, the nozzle-side tip of the impact body protrudes into the nozzle outlet or dips into it.

[0038] To enable the most efficient atomization possible, the impact body should be designed with an elongated shape, as already mentioned. Therefore, one design proposes that an axial length L2 of the atomization surface along the outflow direction be selected to be larger than a diameter Dl of the nozzle outlet opening. However, if, for example, spray angles > 90° are to be realized, the impact body can also be designed with a shape that is larger in diameter than in axial length. In such cases, the full opening angle assumed by the impact body can be 2 <p somit größer als 90 ° aus fallen .

[0039] It can also be provided additionally or alternatively that the axial length L2 of the atomization surface is designed to be greater than an axial length L3 of a / the outlet channel of the injection nozzle, wherein this outlet channel opens into the nozzle outlet opening, and / or greater than the free axial distance LI between the nozzle-side tip of the impact body and the nozzle outlet opening.

[0040] The nozzle outlet opening can have a diameter Dl of at least Dl > 0.5 mm, or even Dl > 1.5 mm, in order to atomize a sufficient quantity of fuel based on the single-hole nozzle concept. Accordingly, the fuel can then exit the nozzle outlet opening as a single, homogeneous and fluid jet. With smaller nozzle outlet opening values, however, the use of a baffle body becomes increasingly less necessary.

[0041] In general, therefore, shapes of the impact body are preferred in which the cross-section of the impact body increases in the outflow direction. However, the impact body does not necessarily have to have strict circular cone symmetry. Nevertheless, a preferred embodiment provides for the impact body to be designed as a cone tapering towards the nozzle outlet opening. This cone can preferably taper to a point and thus form the finest possible tip on the nozzle side. Furthermore, the cone can of course be designed rotationally symmetrically. With such a configuration, the outer surface of the cone can thus form the aforementioned atomization surface. This makes it possible to generate a geometrically precisely shaped spray jet of fine droplets with a homogeneous droplet density distribution.

[0042] A particularly preferred embodiment provides that the cone is designed as a straight circular cone, wherein the longitudinal axis of the circular cone should then preferably coincide with the outflow direction, i.e., this longitudinal axis can, in particular, coincide with a central longitudinal axis of the previously explained outlet channel of the injection nozzle. Furthermore, it is preferred if said circular cone, which forms the impact body, has a full opening angle 2 <p aufweist von mindestens 5° oder von mindestens 10°. Ferner ist es je nach Anwendung vorzuziehen, wenn der volle Öf fnungswinkel 2<p höchstens 135° beträgt (etwa, wenn ein Sprühwinkel von mehr als 90° erzielt werden soll) oder aber höchsten 90° (etwa wenn Sprühwinkel von nur knapp oberhalb von 90° erzielt werden sollen) oder sogar höchstens 70°, oder sogar weniger als 45° (etwa zur Erzeugung eines Sprühwinkels von nur 35°) beträgt.When the longitudinal / rotational axis of the cone / circular cone / impact body and the central axis of the injection nozzle outlet channel coincide, the cone / circular cone is positioned centrally relative to the nozzle outlet opening, with its tip oriented opposite the outflow direction. These angular ranges can each result in a very slender, axially elongated shape of the circular cone.

[0043] The inventive concept of efficient atomization on an inclined atomization surface of the impact body can be described in particular such that a respective surface normal of the atomization surface should form, point by point, a respective angle of incidence for the fluid jet of at least 60°, and preferably of at most 85°, relative to the outflow direction (an angle of incidence of 0° would correspond to a steep, vertical incidence onto the surface of the impact body). With such a configuration, all components of the fluid jet thus strike the atomization surface at relatively large angles of incidence of at least 60° and thus comparatively flatly.

[0044] In other words, the atomization surface itself should be aligned at an angle of no more than 30° and preferably at least 5° to the outflow direction, which can be achieved, for example, with a slim, elongated conical shape of the impact body. This has the crucial technical advantage of enabling high shear forces within the fluid jet and thus particularly efficient atomization. Because of the large angle of incidence, the radially outer portions of the fluid jet hit the atomization surface considerably later than neighboring radially inner portions of the fluid jet. So while inner portions of the fluid jet hit the atomization surface and change direction there, the outer portions initially fly on unhindered at high speed.The resulting difference in the magnitude and direction of the respective velocity vectors in the near-axis and far-axis portions within the cross-sectional profile of the fluid jet emerging from the nozzle outlet opening then generates the desired high shear forces which atomize the fuel efficiently.

[0045] The atomization concept according to the invention is particularly suitable for atomizing fuels at low pressure. Therefore, the fuel injector can be designed as a low-pressure injector for operation at fuel fluid pressures below 100 bar, in particular below 20 bar. For example, a maximum wall thickness of the injection nozzle can be less than 2 mm, so that a massive design is not required, such as would be necessary at operating pressures of 1000 bar.

[0046] According to the inventive concept, direct actuation of the nozzle valve is further preferred, which is why the fuel injector can comprise a preferably electromagnetic actuator for directly actuating the nozzle valve. The actuator can be designed, for example, as an electromagnetic linear actuator. Furthermore, the injector can comprise a flux blocking sleeve which blocks a magnetic flux of the actuator and at the same time ensures a fluidic seal between the fuel and the actuator. The advantage of such integrated direct actuation is, among other things, that it is suitable for rapid actuation in the desired low-pressure range and thus short and precise switching times, and moreover, no separate / pre-fired servo valves need to be used.If the injector is to be retrofitted to an engine, for example, it can be designed and configured to atomize and inject a fuel, in particular methanol, into an intake manifold of the internal combustion engine. For this purpose, for example, a circumferential outer sealing ring can be designed on the injection nozzle, with the aid of which the injector can be inserted into a wall of the intake manifold in a sealing manner. As will be explained below, the injector can also be designed and configured to inject fuel into a combustion device of a heating device.

[0047] The injection nozzle of the injector can preferably be designed as a single-hole nozzle. In this case, the nozzle outlet opening forms the only opening of the injection nozzle from which fuel can escape. This approach therefore differs from the multi-hole nozzles often used to date, in which several spray jets emerge from several openings of the multi-hole nozzle. Since these jets usually diverge and overlap from a certain distance from the nozzle opening, these approaches often have the problem that individual spray jets, or more precisely the droplets contained therein, recombine, which means that the desired small droplet size can no longer be achieved.This problem is precisely avoided in the inventive concept, since the fluid jet, when it emerges from the single nozzle outlet opening (preferably aligned centrally to the impact body), only produces a single diverging but homogeneous jet of very fine fuel droplets after impacting the impact body.

[0048] The nozzle valve mentioned above can have a valve seat, which can be ring-shaped, for example. When the nozzle valve is open, an annular gap can thus be created through which the fuel can flow into the outlet channel without flow disruption. Furthermore, the nozzle valve can have a closure body that is movably mounted, preferably axially along the outflow direction, which rests on the valve seat when the nozzle valve is closed and thus closes the valve seat or the nozzle valve.

[0049] To enable a particularly rapid response of the injector, the invention provides for said valve seat to be designed as a conical seat nozzle. Such a construction can possibly be considered a pintle nozzle. In any case, it is a single-hole nozzle.

[0050] In other words, it can be provided that when the nozzle valve is closed, the said closure body, which closes the valve seat, dips into a conical seat (within the nozzle valve), which conical seat preferably tapers conically. In this case, an inlet contour of the conical seat can form the valve seat. A preferred embodiment provides that the conical seat opens / leads directly into the outlet channel of the injection nozzle, with the outlet channel in turn opening into the nozzle outlet opening of the injection nozzle. This means that the said cone can have a central through-opening opening into the outlet channel, through which the fuel flows into the outlet channel. Such a design of the nozzle valve is particularly advantageous in order to avoid flow separation and the resulting turbulence and thus to enable the most homogeneous speed profile of the fuel when exiting the outlet nozzle.As a result, a flow field of the fuel at the outlet nozzle can be obtained which is homogeneously aligned and shows a homogeneous distribution of the velocity over the cross section of the escaping fuel jet.

[0051] For the best possible homogenization of the fluid flow, it is particularly preferred if an axial length L4 of the conical seat along the outflow direction, measured from the beginning of the outlet channel to the valve seat, is at least 20% of an axial length L3 of the outlet channel. In this case, the conical seat fluidically forms a type of (possibly second) chamber in which the fluid flow can be homogenized (particularly when using a distributor upstream of the valve seat). Preferably, a rounded portion can be designed at the transition from the conical seat to the outlet channel in order to further optimize the flow properties. It should also be mentioned that it is further preferred if the entire outlet channel, preferably and part of the conical seat, is kept clear when the valve is closed, i.e. the closure body can only partially penetrate into the said cone / conical seat, but not into the outlet channel.This allows the desired homogeneous fluid jet to be produced.

[0052] In contrast to so-called multi-hole nozzles, the nozzle outlet opening of the injector can have a diameter Dl of at least 0.5 mm or even at least 1.5 mm in order to be able to atomize a sufficient amount of fuel in a short time.

[0053] It can further be provided that for a ratio of a diameter Dl of the nozzle outlet opening and a minimum diameter D4 of a fuel supply channel, which is arranged upstream of the nozzle outlet opening in the nozzle valve and can be configured in particular in the closure body, the following applies: Dl > 0.3 D4, preferably the following can apply: Dl > 0.4 D4. Such features can also support the fact that the fuel can be delivered through the injector, in particular through the aforementioned actuator, with fast switching times and can also emerge from the nozzle outlet opening as a homogeneous and liquid fluid jet.

[0054] The nozzle valve can preferably have a movably mounted closure body for closing the valve seat of the nozzle valve (which can be designed as explained above), wherein this closure body can preferably be actuated electromagnetically, namely by direct actuation with the aid of an electromagnetic actuator, as already mentioned. The nozzle valve can therefore preferably be designed as an electromagnetically and / or directly actuated and / or as an electronically controllable valve. This is because the time and duration of the fuel injection can be regulated / adjusted with precise timing and, above all, in a temporally variable manner. In addition, very short switching times of less than 2 ms can be achieved and the switching time can be set very precisely; typical switching times in application, however, can be in the region of 20 ms.In this approach, the actuator actuates the nozzle valve directly and not indirectly via fluid pressure, as is the case when using servo valves.

[0055] An injector according to the invention can alternatively also be equipped with a mechanically or hydraulically operated nozzle valve, depending on the requirements of the specific application.

[0056] In order to shorten the switching times of the injector and also to achieve a homogenization of the fluid jet, one embodiment provides that the closure body has a

[0057] Has or forms a fuel supply channel which is divided into at least two channel arms / two lines by means of a distributor. This ensures that, even when the nozzle valve is closed, a pre-chamber which is located upstream of the valve seat in the direction of fuel flow and can preferably be ring-shaped, is / remains evenly filled with fuel. In the pre-chamber, fuel can therefore be held in the immediate vicinity of the valve gap / valve seat to be opened, in order to enable fuel to be injected with almost no delay. This is advantageous for achieving excellent short-term dynamics during atomization (which is a challenge, for example, with other atomization concepts such as swirl nozzles).

[0058] Such a valve design allows for rapid response and opening of the valve, even when operating at low fluid pressures of < 20 bar. The pre-chamber allows fuel to flow evenly through a comparatively large cross-section of the valve opening in the area of ​​the valve seat, and is always filled with fuel. Starting from the pre-chamber, the fuel can flow through a common outlet channel of the injection nozzle after passing through the valve opening in the area of ​​the valve seat. This outlet channel is located upstream of the nozzle outlet opening and preferably has a circular cross-section.In this way, it can be achieved that the fuel exits the nozzle outlet opening as a still liquid, homogeneous fluid jet after passing through the outlet channel, whereby due to the nozzle design, a homogeneous velocity distribution over the cross section of the fluid jet can be achieved, as a prerequisite for subsequent effective atomization of the fuel.

[0059] Likewise, for rapid switching of the injector, it is advantageous if the smallest diameter D2 of the valve seat of the nozzle valve is at least 1.5 times, but preferably twice as large, than the diameter D1 of the nozzle outlet opening. This makes it possible for a comparatively large volume flow of fuel to be released even with a small axial adjustment path of the closure body, which results in the desired rapid actuation of the injector. In addition, the design of the aforementioned distributor makes it possible for the two fluid flows flowing through the open valve seat to combine to form a homogeneous fluid flow, thus allowing a homogeneous fluid jet to emerge from the nozzle outlet opening of the injection nozzle.

[0060] It is also preferred if the outlet channel is oriented such that the outflow direction in which the fluid jet exits the nozzle outlet opening when the nozzle valve is open coincides with a movement axis in which the closure body, which closes the valve seat, is adjustable / movable. Respective longitudinal axes of the two mentioned channel arms can also be oriented in the outflow direction and thus enclose an angle with the outflow direction of less than 90°, preferably less than 70°.

[0061] Especially when the injector is to atomize methanol, it is crucial to generate high shear forces when the still liquid fluid jet hits the atomization surface of the impact body. In this context, a preferred embodiment provides that the atomization surface of the impact body has a boundary which separates an axially front region of the atomization surface from an axially rear region of the atomization surface. This boundary, which can be designed, for example, in the form of a step or a curve, preferably runs around a longitudinal axis of the impact body. In order to optimize the atomization, it is provided that the atomization surface is aligned flatter or steeper to the outflow direction in the front region than in the rear region.With such features, it can be achieved that a respective surface normal of the atomizing surface forms a respective angle of incidence 0 for the fluid jet at any point relative to the outflow direction, which angle is larger or smaller in the front area (preferably always, i.e., for all possible points on the atomizing surface in the respective front or rear area) than in the rear area of ​​the atomizing surface. At the said boundary or step, the opening angle assumed by the impact body can increase abruptly.

[0062] To achieve this objective, an internal combustion engine is also proposed, as already explained above. According to the invention, the internal combustion engine comprises at least one fuel injector configured according to the invention, i.e., according to one of the claims directed to an injector and / or as described above. Furthermore, the respective fuel injector is arranged such that it can deliver the (finely) atomized fuel into the intake manifold or a turbocharger of the internal combustion engine.

[0063] In this context, the invention also proposes an associated method for operating this internal combustion engine. Here, a liquid fuel such as methanol is atomized in the intake manifold by means of the injector, so that the finely atomized methanol / fuel can then pass from the intake manifold through the intake valve and into the combustion chamber of the internal combustion engine. In order to achieve very fast switching times and synchronization with the combustion process in the combustion chamber, it is preferred if the fuel injector is controlled electronically in synchronization with the intake valve of the internal combustion engine. For this purpose, the injector can have an electromagnetically actuated nozzle valve, as already explained.Accordingly, the injector can also include an electrical / electronic interface via which it can receive control signals for controlling / actuating the nozzle valve.

[0064] This process is particularly suitable for marine engines when methanol is to be introduced into the combustion chamber via the intake manifold and the intake valve by way of a secondary injection (e.g., in addition to, or as a supplement to, or alternative to, diesel injection directly into the combustion chamber). For example, methanol to diesel mixture ratios of 70:30 can be specifically adjusted, with the diesel fuel then serving as the ignition source.

[0065] Thus, in a specific application of this method, for example, a methanol-diesel-air mixture can be produced / introduced into the combustion chamber, with a diesel injector injecting the diesel fuel directly into the combustion chamber, and the diesel fuel thus causing the ignition. Since the injector according to the invention injects methanol into the intake manifold, for example for reasons of space, the finely atomized methanol mixture must flow through the recently opened intake valves into the respective combustion chamber. For this to function correctly, very short switching times of typically 5 to 20 ms must be maintained, with the injection time having to be synchronized with the intake valves. Therefore, electronic control will typically be necessary, which is possible with the design of the electromagnetic actuation of the injector according to the invention as explained above.

[0066] In order to enable efficient and environmentally friendly energy generation from clean fuels, a specific use of an injector as explained above, which can be designed according to one of the claims directed to an injector, is also proposed. This use provides that the fuel injector is used to atomize and inject liquid fuel such as methanol, in order to thereby enable particularly favorable combustion of the liquid fuel / methanol. For example, with an injector according to the invention, the liquid fuel / methanol can be injected into an intake manifold or a turbocharger of an internal combustion engine or (particularly in maritime applications, for example on ships) into a burner device of a heating device in order to be able to use methanol as fuel there too, for example.In this way, for example, hot air blowers or hot steam generators on ships can be efficiently operated with methanol. This approach can be used, for example, to heat the interior of ships or, before starting the ship's engine, to precondition the fuel system, the fuel tank, and the ship's engine itself (which is often not capable of cold starting). The invention thus makes a particularly important contribution to ships that can be powered entirely by methanol, thus enabling the long-term reduction of CO2 emissions, including in shipping.

[0067] The invention will now be described in more detail using exemplary embodiments, but is not limited to these embodiments. Further developments of the invention can be derived from the following description of a preferred embodiment in conjunction with the general description, the claims, and the drawings.

[0068] In the following description of various embodiments of the invention, elements which correspond in their function are given the same reference numbers even if they have a different design or shape.

[0069] It shows: Figures 1 to 4 show a first possible embodiment of an injector according to the invention, wherein Figure 1 is a perspective view, Figure 2 is a partial longitudinal section, Figure 3 is a rear view and Figure 4 is a front view of the injector, Figures 5 to 7 are analogous views of a second embodiment of an injector according to the invention, Figures 8 to 10 are a third embodiment of an injector according to the invention,

[0070] Figure 11 shows a detail of the longitudinal section of the injector from Figure 7,

[0071] Figure 12 is a further enlarged view of the detail from Figure 11 with a focus on the impact body according to the invention and finally

[0072] Figure 13 possible embodiments of the inventive

[0073] Impact bodies with a stepped outer contour that defines a front first region and a rear second region of the atomization surface of the impact body.

[0074] Figures 1 to 4 show a first example of a fuel injector 1 designed according to the invention, with which liquid methanol can be finely atomized as fuel. For this purpose, the fuel is introduced into the injector 1 via a fluid connection 22 and thus reaches a

[0075] Fuel supply channel 7, which can be seen in the longitudinal sectional view of Figure 2. Starting from the fuel supply channel 7, which is partially formed in a movably mounted closure body 6, with which a valve seat 13 of a nozzle valve 4 of the injector 1 can be closed, the fuel reaches a pre-chamber 9 via channel arms 8 (distributor 10) formed in the closure body 6, as can be seen particularly well in the detailed view of Figure 11, which shows details of a comparable injector 1 according to Figure 7. Therefore, if there is fuel pressure on the inlet side of the injector 1, the pre-chamber 9 is always filled with fuel, even before the nozzle valve 4 opens.

[0076] If a corresponding control signal is transmitted to the injector 1 via the control cable 21 (see Figure 1), the closure body 6 can be moved electromagnetically in the z-direction with the aid of an actuator 33 against the restoring force of a return spring 30 (see Figure 2), whereby the nozzle valve 4 of the injector 1 is directly actuated and thus opened. The shown flux blocking sleeve 24 of the actuator 33 ensures that it remains "dry", i.e., does not come into contact with the fuel, and also that the magnetic flux can be specifically blocked.As a result of the activation of the actuator 33, the fuel flows from the pre-chamber 9 through the valve seat 13, which is formed by the inlet contour of a corresponding conical seat 19, into the said conical seat 19 and from there into an outlet channel 12, which in turn opens into a circular nozzle outlet opening 3 of the injection nozzle 2 of the injector 1, as can be clearly seen from a comparison of Figures 1 and 2 (see also the detailed view of Figure 11).

[0077] With the nozzle valve 4 shown in Figure 2 and Figure 11, the flow of fuel from the fuel supply channel 7 through the injection nozzle 2 can be controlled (and in particular specifically regulated by means of appropriate control electronics), so that when the nozzle valve 4 is open, a homogeneous fluid jet of the fuel can emerge from the nozzle outlet opening 3 along the outflow direction 5 illustrated in Figure 2 and Figure 11 (which corresponds to the longitudinal axis of the outlet channel 12).

[0078] The fluid jet emerging from the nozzle outlet opening 3 then traverses a free path 14 in air (compare Figure 2 and Figure 11) and then strikes an atomization surface 15 oriented obliquely to the outflow direction 5, which is formed by the impact body 11 shown in Figure 2. The impact body 11, which is designed as a separate component, is suspended freely above the nozzle outlet opening 3 by means of a suspension 35.

[0079] More precisely, the impact body 11 is designed in the form of a pointed and slender cone and is suspended freely in front of the nozzle outlet opening 3 by means of a bridge 16 which has two legs 17 (cf. Fig. 1). The impact body 11 forms part of the injector 1 since the bridge 16, as can be seen in Figure 1, is supported on the injection nozzle 2 via the two legs 17. The impact body 11 was manufactured separately as a turned metal part and then connected to the suspension 35 designed as a bridge 16 by means of a rivet connection 38 (cf. the cross section in Fig. 2; this connection can also be produced, for example, by flanging, welding or gluing). In Figure 5 and Figure 7, the previously mentioned radial plane 36 is also shown in the area of ​​the front end of the impact body 11, which is kept completely free except for the suspension 35 and its legs 17 (see Fig. 5).In the second embodiment according to Figures 5 to 7 as well as in the third embodiment according to Figures 8 to 10, the impact body 11 is designed identically, namely as a straight circular cone and thus as a rotationally symmetrical cone tapering towards the nozzle outlet opening 3. Accordingly, this injector generates a single, homogeneous and rotationally symmetrical (with respect to the distribution of droplets in a radial plane) spray jet 37 (see Figure 11). The outer surface of this circular cone forms the atomization surface 15.

[0080] In order to generate high shear forces when the fuel hits the atomizing surface 15, the latter is inclined flatly to the outflow direction 5. Accordingly, in the design of the impact body 11 shown in the figures, the atomizing surface 15 is arranged within an imaginary circular cone, the tip 18 of which points towards the nozzle outlet opening 3 and the full opening angle 2 <p weniger als 40° beträgt (vgl. dazu auch die detaildarstellung gern. figur 11) . wie man in 11 (die eine detailansicht der 7 zeigt) anhand gepunkteten linien erkennt, fällt sprühwinkel 32 des vom injektor 1 erzeugten sprühstrahls 37 (also winkelbereich, unter dem kraftstoff-tröpfchen aus austreten) etwas größer aus. je nach anforderungen konkreten anwendung können mit erfindungsgemäßen konzept aber>90°, whereby the opening angle 2 <p des Prallkörpers 11 entsprechend größer gewählt werden kann. Durch Austausch des Prallkörpers 11 kann dabei sehr einfach der gewünschte Sprühwinkel je nach Kundenwunsch angepasst werden.

[0081] In the detailed view of Figure 12, it can be clearly seen that the maximum diameter D3, which the atomization chamber fills in the xy radial plane, is selected to be at least as large as the diameter Dl of the nozzle outlet opening 3, so that the entire fluid jet emerging from the nozzle outlet opening 3 actually impacts the atomization surface 15.

[0082] In the first example of Figures 1 to 4, the impact body 11 is suspended from a two-legged bridge 16, as can be clearly seen in particular in the front view of Figure 4. In the example of Figures 8 to 10, however, this bridge 16 is supported on the injector 1 by means of three legs 17, whereby the impact body 11 is suspended more robustly and thus less subject to vibration. In both embodiments, however, the jet of fine droplets resulting from the atomization of the fuel on the impact body 11 can spread out from the impact body 11 into free space almost unhindered. In Figure 4 one can clearly see that only very narrow angular ranges in the xy radial plane are blocked by the bridge 16 (namely in the 12 o'clock and 6 o'clock positions), while the remaining angular range of more than 300° in total is kept free (compare the dotted block arrows).The same applies to Figure 9, where three respective areas are kept free, which, when added together, also amount to more than 300°. In the freed angular areas, the fuel can thus exit the injector 1 after atomization unhindered and without contact with components of the injector 1.

[0083] This also applies to the designs according to the second and third design examples, in which, as can be seen in Figures 5 and 8, a pot 27 is designed as part of the injection nozzle 2, which surrounds the impact body 11 in a ring shape (i.e. closed) and thus protects it from damage. The cross-section in Figure 7 clearly shows that the space defined by the pot 27 and in which the impact body 11 is arranged has no other connection (apart from the front opening) to the external environment (and is therefore designed as a type of blind hole), with in particular no gas supply channels being formed in the area of ​​the nozzle outlet opening. Contact between the fuel droplets and the surrounding gas atmosphere therefore only occurs in the area of ​​the radial plane 36, which is illustrated in Figures 5 and 7.This design is of great advantage for the effectiveness of the atomization, which, as explained, is based on shear forces.

[0084] In Figures 7 and 10 in particular it can be clearly seen that the front edge 20 of the pot 27 is set back so far from the bridge 16 against the direction of outflow 5 that here too the fuel mist produced at the impact body 11 can be released into the room largely unhindered (cf. also the radial plane 36 in Figure 5). If one follows the extension of the atomisation surface 15 in the direction of outflow 5 in Figure 11, as shown by the two inner dot-dash lines, then in conjunction with the corresponding front view in Figure 6 one can clearly see that in this example too an angular range of over 300° in total, related to the circumferential angle in the xy radial plane illustrated in Figure 6 with the block arrows there, is kept free.

[0085] From the outer dash-dot lines in Figure 11 it can also be seen that the said angular range is also kept free for an imaginary second circular cone which emanates from the tip 18 of the impact body 11 and has a full opening angle of approximately 70°, and is thus much wider than the circular cone of the impact body 11. Accordingly, a resulting spray jet with a full spray angle of, for example, 60° could be generated here with the injector 1 without fuel being able to deposit directly on the inner wall of the pot 27. In the detailed views of Figures 11 and 12 it can also be clearly seen that the outlet channel 12 is kept free along its entire length L3, so that the fluid jet which issues from the nozzle outlet opening 3 has a circular disk-shaped cross-section.In order to enable efficient atomization, the axial length L2, as can be clearly seen in Figure 11, is chosen to be significantly larger than, for example, the diameter Dl of the nozzle outlet opening 3, but also larger than the axial length L3 of the outlet channel 12. The axial distance LI between the nozzle-side tip 18 of the impact body 11 and the nozzle outlet opening 3, on the other hand, is chosen to be precisely smaller than the diameter Dl and also smaller than the axial length L2 of the atomization surface 15.

[0086] In the illustrated rotationally symmetrical design of the impact body 11, the cross-section increases in the outflow direction 5. However, depending on the application, a rotationally symmetrical shape may not necessarily be required. For efficient atomization, it is more important to achieve comparatively large angles of incidence 0 for the fluid jet by means of a suitable orientation of the atomization surface 15.

[0087] As Figure 13 shows, a circumferential step can also be formed in the atomizing surface 15 as a boundary 31, which separates an axially front region 28 of the atomizing surface 15 from an axially rear region 29. Instead of such a step, the transition between the two regions 28 and 29 can also be designed to be continuous, so that the angle of incidence θ does not change suddenly, but continuously. In the left-hand variant a), the atomizing surface 15 is aligned more flatly to the outflow direction 5 in the front region 28 than in the rear region 29; in the second variant b), which is shown on the right in Figure 13 and is preferred over variant a), the situation is exactly the opposite.In Figure 12, for example, it can be clearly seen that, due to the slender shape of the circular cone which defines / delimits the atomisation surface 15 of the impact body 11, (point by point) a respective surface normal (illustrated as a dashed line) of the atomisation surface 15 to the outflow direction 5 forms a respective angle of incidence 0 for the fluid jet emanating from the nozzle outlet opening 3 of at least 60°. This ensures that the radially outer regions of the fluid jet impact the atomisation surface 15 considerably later than the radially inner regions. Correspondingly high shear forces result as soon as the inner regions of the fluid jet impact the atomisation surface 15, while the outer regions of the fluid jet continue to fly in the outflow direction 5.

[0088] With regard to the design of the nozzle valve 4, it is also worth mentioning that the valve seat 13 is designed as a conical seat nozzle seat, because the closure body 6 dips into the already described conical seat 19, the inlet contour of which forms the valve seat 13 of the nozzle valve 4. In this case, however, the closure body 6 only partially, but not completely, dips into the said cone, so that even when the nozzle valve 4 is completely closed, a conically tapered chamber remains / follows the valve seat 13 in the flow direction, which in turn opens into the previously described outlet channel 12 of the injection nozzle 2. In Figure 12 it can be clearly seen that the smallest diameter D2 of the valve seat 13 formed in the inlet contour of the conical seat 19 is selected to be more than 50% larger than the diameter Dl of the nozzle outlet opening 3.Accordingly, even with only minimal opening of the nozzle valve 4, a significant volume flow of fuel can be released by slightly moving the closure body 6 in the negative z-direction, so that the injector 1 can achieve a fast switching time.

[0089] In summary, for the efficient atomization of fuels such as methanol or ethanol at low pressures of less than 100 bar, an injector 1 is proposed. The injector 1 has a static impact body 11, on which a homogeneous fluid jet of fuel, generated by an injection nozzle 2 of the injector 1, can be atomized into microscopic droplets. The fluid jet emerging from a nozzle outlet 3 of the injection nozzle 2 falls, preferably at comparatively large angles of incidence of at least 60°, onto an atomization surface 15 formed by the impact body 11, thereby achieving high shear forces and thus efficient atomization.

[0090] List of reference symbols Fuel injector Injection nozzle Nozzle outlet opening (formed at the end of 2) Nozzle valve (is upstream of 3, controls the flow of fuel through 2 / 3) Outflow direction (direction in which the fuel exits from 3) Closure body (closes 13) Fuel supply channel (formed in 6) Channel arm (branched off from 7 by means of a 10) Pre-chamber Distributor Impact body Outlet channel (from 2, opens into 3;is 13 downstream in the direction of fuel flow) valve seat (is closed by 6) free path (between 3 and 11) atomizing surface bridge (carries 11) leg (of 16, supports 16 on 2) tip (of 11, aligned to 3 on the nozzle side) conical seat edge (of 27) control cable (for controlling M) fluid connection magnet flux blocking sleeve (blocks a magnetic flux from 33 and seals 33 against the fuel fluidically) armature (external) seal pot front area (of 15) rear area (of 15) return spring 31 limit (between 28 and 29);

[0091] 32 spray angles

[0092] 33 electromagnetic actuator

[0093] 34 Fluid jet

[0094] 35 Suspension

[0095] 36 Radial plane

[0096] 37 Spray jet (preferably with rotationally symmetrical cross-section)

[0097] Design parameters

[0098] Dl Diameter of the nozzle outlet opening

[0099] D2 smallest diameter of the valve seat

[0100] D3 maximum diameter that the atomization surface fills in the radial plane

[0101] D4 Diameter of the fuel supply channel

[0102] LI free axial distance LI along 5 between a nozzle-side tip of 11 and 3

[0103] L2 axial length of 15 along 5

[0104] L3 axial length of 12

[0105] L4 axial length of 19

[0106] 0 angle of incidence (from 34 to surface of 11 )

[0107] 2

Claims

Claims 1. Fuel injector (1) for atomizing a liquid fuel with - an injection nozzle (2) having a nozzle outlet opening (3) from which a homogeneous fluid jet of the fuel can emerge in a straight line along an outflow direction (5), and with - a nozzle valve (4) with which a flow of fuel through the injection nozzle (2) can be released, characterized in - that the fuel injector (1) comprises a freely suspended impact body (11) which follows the nozzle outlet opening (3) in the outflow direction (5) and forms an atomisation surface (15) for atomising the fuel, which is oriented obliquely to the outflow direction (5), preferably rotationally symmetrical, - in particular so that the entire fluid jet emerging from the nozzle outlet opening (3) strikes the atomizing surface (15) of the impact body (11) after traversing a free path (14) in air and is atomized into droplets there.

2. Fuel in ector (1) according to claim 1, - wherein the impact body (11) is connected as a separate component, preferably as a turned metal part, by means of a, in particular form-fitting and / or material-fitting, connection (38) to a separate suspension (35) which holds the impact body (11) in position above the nozzle outlet opening (3) and / or - wherein the atomizing surface (15) is arranged within an imaginary circular cone, the tip (18) of which points towards the nozzle outlet opening (3) and the full opening angle 2 <p höchstens 130°, 60°, 45° oder 35° beträgt.

3. kraftstoff-injektor (1) nach einem der vorhergehenden ansprüche, wobei ein maximaler durchmesser d3, den die zerstäubungsfläche (15) in einer senkrecht zur ausströmungsrichtung (5) verlaufenden radialebene ausfüllt, wenigstens so groß gewählt ist, dass gilt: d3>0.50 Dl, or D3 > 0.85 Dl or D3 > 0.90 Dl or even D3 > Dl, with Dl being the diameter of the nozzle outlet opening (3), - in particular so that even the radially outermost parts of the fluid jet still hit the atomization surface (15).

4. Fuel in ector (1) according to one of the preceding claims, wherein the impact body (11) is suspended by means of a suspension (35), preferably designed separately from the impact body (11), - that an extension of its atomising surface (15) aligned obliquely to the outflow direction (5) is kept free in an angular range of at least 180° in total, preferably of at least 240°, relative to an angle which runs around the outflow direction (5) in a radial plane running perpendicular to the outflow direction (5), and / or - that a radial plane (36) running perpendicular to the outflow direction (5) and located in the region of the front end of the impact body (11) is kept completely free with the exception of the suspension (35), - in particular so that fuel atomized on the impact body (11) can escape from the same in the areas / angle areas kept free and without contact with components of the fuel injector (1).

5. Fuel injector (1) according to one of the preceding claims, wherein an outlet channel (12) opening into the nozzle outlet opening (3) is kept free at its outlet-side end, but preferably completely, - in particular so that the fluid jet emerging from the nozzle outlet opening (3) has a circular disk-shaped cross-section.

6. Fuel injector (1) according to one of the preceding claims, wherein the impact body (11) is mounted on one leg or by means of a bridge having two legs (17a, 17b) (16) , preferably by means of a bridge (16) having three legs (17a, 17b, 17c) which serves as a suspension (35), is suspended freely above the nozzle outlet opening (3).

7. Fuel in ector (1) according to one of the preceding claims, wherein an axial distance LI along the outflow direction (5) between a nozzle-side tip (18) of the impact body (11) and the nozzle outlet opening (3) is selected to be so small that: LI < 1.75 Dl, or LI < 1.50 Dl or even LI < Dl, with Dl being the diameter of the nozzle outlet opening (3) and / or - wherein an axial length L2 of the atomization surface (15) of the impact body (11) along the outflow direction (5) is selected to be greater than a diameter Dl of the nozzle outlet opening (3) and / or greater than an axial length L3 of an outlet channel (12) of the injection nozzle (2), wherein the outlet channel (12) opens into the nozzle outlet opening (3).

8. Fuel injector (1) according to one of the preceding claims, wherein a cross section of the impact body (11) increases in the outflow direction (5) and / or - wherein the impact body (11) is designed as a preferably rotationally symmetrical cone tapering towards the nozzle outlet opening (3), preferably with a rounded tip, - in particular wherein a lateral surface of the cone atomization surface (15), - preferably wherein the cone is designed as a right circular cone, particularly preferably with a full opening angle 2 <p von 2 5°, especially from 2 10°, preferably and from 2 <p < 130°, insbesondere von 2<p < 90°.

9. Fuel injector (1) according to one of the preceding claims, wherein a respective surface normal of the atomizing surface (15) forms a respective angle of incidence 0 for the fluid jet of at least 60°, preferably and of at most 85°, point by point to the outflow direction (5).

10. Fuel injector (1) according to one of the preceding claims, wherein the fuel injector (1) - a preferably electromagnetic actuator (33) for directly actuating the nozzle valve (4), in particular with a flow barrier sleeve (24) fluidically sealing the actuator (33) against the fuel, and / or - is designed as a low-pressure injector (1) for operation at fluid pressures of the fuel below 100 bar, in particular below 20 bar, and / or - is intended and arranged for atomising and injecting methanol, in particular into an intake manifold of an internal combustion engine.

11. Fuel injector (1) according to one of the preceding claims, wherein the injection nozzle (2) is designed as a single-hole nozzle, in particular so that the nozzle outlet opening (3) is the only opening of the injection nozzle (2) from which fuel can exit.

12. Fuel injector (1) according to one of the preceding Claims, wherein a valve seat (13) of the nozzle valve (4) is designed as a conical seat nozzle seat and / or wherein when the nozzle valve (4) is closed, a closure body (6) closing the valve seat (13) dips into a conically tapered conical seat (19), - in particular, wherein an inlet contour of the conical seat (19) forms the valve seat (13) and / or wherein the conical seat (19) leads into an outlet channel (12) of the injection nozzle (2), which in turn opens into the nozzle outlet opening (3).

13. Fuel injector (1) according to one of the preceding claims, - wherein the nozzle outlet opening (3) has a diameter Dl of at least Dl > 0.5 mm, or even Dl > 1.5 mm, - in particular so that the fuel can emerge from the nozzle outlet opening (3) as a single homogeneous and liquid fluid jet.

14. Fuel in ector (1) according to one of the preceding claims, wherein the nozzle valve (4) has a preferably electromagnetically actuatable, movably mounted closure body (6) for closing a valve seat (13) of the nozzle valve (4), - in particular, wherein the closure body (6) has a fuel supply channel (7) which is divided into at least two channel arms (8a, 8b) by means of a distributor (10), - preferably so that even when the nozzle valve is closed (4) a pre-chamber (9) arranged upstream of the valve seat (13) in the direction of flow of the fuel, preferably annular, is filled with fuel.

15. Fuel injector (1) according to one of the preceding claims, wherein the atomization surface (15) has a preferably circumferential boundary (31), in particular in the form a step or curve which separates an axially front region (28) of the atomizing surface (15) from an axially rear region (29) of the atomizing surface (15) and - wherein the atomizing surface (15) in the front region (28) is a) flatter or b) steeper to the outflow direction (5) than in the rear region (29), - in particular so that a respective surface normal of the atomization surface (15) forms a respective angle of incidence 0 for the fluid jet point by point to the outflow direction (5), which angle of incidence 0 in the front region (28) is preferably always a) greater than or equal to or b) smaller than in the rear region (29).

16. Internal combustion engine with - at least one combustion chamber, - an intake manifold upstream of the combustion chamber, and with - at least one inlet valve with which an inflow of a fuel-air mixture from the intake manifold into the combustion chamber can be controlled, characterized in that - that the internal combustion engine comprises at least one fuel injector (1) according to one of the preceding claims, which is arranged so that it can deliver finely atomized fuel into the intake manifold.

17. A method for operating an internal combustion engine designed according to the preceding claim 16, - wherein liquid fuel, in particular methanol, is finely atomized in the intake manifold by means of the fuel injector (1) in order to then be injected through the inlet valve through into the combustion chamber, - preferably wherein the fuel injector (1) is controlled electronically synchronized with the inlet valve.

18. Use of a fuel injector (1) according to one of the Claims 1 to 15, - wherein the fuel in ector (1) is used for atomizing and injecting liquid fuel, in particular methanol, - in particular wherein the methanol is injected into an intake manifold or a turbocharger of an internal combustion engine or into a burner device of a heating device.

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