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

Abstract

For the efficient atomization of liquid fuels such as methanol or ethanol at low pressures of less than 100 bar, an injector (1) is proposed which 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 opening (3) of the injection nozzle (2) of the injector (1) preferably falls at comparatively large angles of incidence of at least 60° onto an atomization surface (15) formed by the impact body (11), whereby high shear forces and thus efficient atomization can be achieved.

Description

[0001] 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. During operation, the nozzle valve can be permanently pressurized on the inlet side. The quantity of fuel briefly delivered by the fuel injector (more precisely: by the injection nozzle) can be adjusted / specified, for example, via the duration of the opening of the nozzle valve.

[0002] The invention further relates to an internal combustion engine having at least one combustion chamber, an intake manifold disposed 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.

[0003] 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, may be injected in addition to diesel fuel in a sufficiently fine atomization to enable operation with both fuels, especially simultaneously.

[0004] 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.

[0005] Based on this technical background, the object of the invention is to provide an injector with which, in the low-pressure range (< 100 bar), novel fuels such as methanol or ethanol, to name just two examples, can be very finely atomized into a fuel mist consisting of very fine droplets, for example with a typical average (temperature-dependent) droplet size in the range of approximately [200 .. 400] µm, with fast injector switching times. The aim is to reliably and reproducibly achieve the desired microscopic droplet size and thus a high degree of atomization of the fuel mist generated by the injector, in order to ensure high combustion efficiency and also to positively influence the resulting exhaust gases.

[0006] To achieve this object, the features of claim 1 are provided according to the invention for a fuel injector, which can be used in particular for injecting fuel into a desired area of an internal combustion engine. In particular, to achieve the object in an injector of the type mentioned above, 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 oriented obliquely to the outflow direction for atomizing the fuel. The atomization surface can preferably be rotationally symmetrical.

[0007] 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.

[0008] Such an injector design can, in particular, ensure that the entire fluid jet emerging from the nozzle outlet, after traversing a free path in air, hits the atomizing surface of the impact body, where it is atomized into (typically microscopic) droplets. Therefore, the atomizing surface could also be referred to or understood as an impact surface, since the fluid jet rebounds from the atomizing surface and is thus deflected from the original outflow direction. The deflection for individual radial portions of the fluid jet can also be configured 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 relative 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 hit if it were to propagate in a straight line from the nozzle outlet opening.

[0009] After the fluid jet of fuel is atomized at 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 (e.g., in an intake manifold) also influence the formation of the spray angle. Therefore, tests and / or simulations are typically necessary to define an optimal shape of the impact body for a desired spray angle.

[0010] 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 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).

[0011] A second effect, which is overcome by the impact body according to the invention, is that high shear forces or high energy must be applied to break up the methanol fluid at its surface in order to initiate droplet formation / atomization in the first place. It should be noted 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.

[0012] The inventive concept of using a freely suspended impact body following the outlet opening 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 with low pressures of typically no more than 10-12 bar in the fuel supply lines for safety reasons. With a fuel injector according to the invention, it is also possible to serve the typically very large cross-sections of the cylinders of marine engines.

[0013] According to the invention, the object can also be achieved by further advantageous embodiments, as defined in the subclaims and explained in detail below: For efficient fuel atomization, it is advantageous if the atomizing surface is arranged within an imaginary circular cone whose tip points toward the nozzle outlet and whose full aperture angle 2φ is no more than 130°. However, for certain applications requiring small spray angles, it may be advantageous if the full aperture angle 2φ is no more than 60°, no more than 45°, or even no more than 35°. For a rebound pin in the shape of a right circular cone with a diameter D=2r and a height H, the full aperture angle is, for example, 2φ = 2 arcsin [r / H] = 2 arcsin [D / 2H].

[0014] 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 opening angle of the imaginary circular cone that defines the atomization surface is, for example, 2 × 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 opening angle is selected to be even smaller, correspondingly larger angles of incidence θ result.

[0015] 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, while being comparatively slender transversely to the outflow direction or elongated in 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.

[0016] It should also be noted that the opening angle of the fine droplet spray cone emanating from the impact body (often referred to as the spray angle or fan-out angle) will generally be somewhat larger than the 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.

[0017] 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 D1, preferably D3 ≥ 0.85 D1 or particularly preferably D3 ≥ 0.90 D1 or even D3 ≥ D1, where D1 is the diameter of the nozzle outlet opening. In individual cases, D3 can therefore be selected to be at least 10% larger than D1, for example. Such configurations can in particular ensure that even the radially outermost parts of the fluid jet (i.e. regions of the cross-section of the fluid jet remote from the axis) can still impinge on the atomization surface. If, on the other hand, diameter D3 < 0.8 D1 (approximately: D3 = 3.1 mm and D1 = 2.5 mm), efficient atomization is generally no longer achieved for all fuels; Depending on the fuel, values below this can still lead to usable results.

[0018] A further preferred embodiment provides that the impact body is suspended 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 the impact body is suspended from a bridge with only two legs, for example, a two-part spray jet can be created. For example, if the discharge direction is considered the z-axis in a Cartesian coordinate system, the angle surrounding the z-axis thus runs in the xy-plane (as a radial plane perpendicular to the discharge direction).

[0019] Such a design particularly prevents the fine fuel droplets formed on the impact body from excessively depositing on downstream structures as soon as they fly beyond the impact body in the same direction or diagonally to the outflow direction. In the case of injection nozzles with a comparatively narrow and fully circumferential nozzle opening, from which a fluid jet already atomized by an impact body must first emerge, it has been observed that in such a design there is a tendency for already atomized 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 atomization can no longer be achieved. The design described above largely prevents such deposits of already atomized fuel.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.

[0020] A preferred embodiment even proposes that not only the extension of the atomization surface in the direction of fuel flow, but rather an imaginary second circular cone emanating from the tip of the impact body, be kept (i.e., at least partially) clear within the aforementioned angular ranges. 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.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 unhindered into the room without further contact with the injector, so that the small droplet size produced is maintained.

[0021] 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 deposition (i.e. precipitation on the injector).

[0022] 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 aforementioned design.

[0023] For example, the impact body can be suspended on one leg / one side above the nozzle outlet. In this case, the suspension should be designed to be solid to prevent unwanted vibrations of the impact body during injector operation.

[0024] A preferred embodiment provides for the impact body to be 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.

[0025] 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. This is especially true if the jet emerging from the nozzle outlet does not hit the impact body perfectly centrally, but rather slightly obliquely, this can cause vibrations in the impact body, which adversely affect 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°).

[0026] 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.

[0027] 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 L1 along the outflow direction between a nozzle-side tip of the impact body and the nozzle outlet opening is selected so small that: L1 ≤ 1.75 D1 (approximately: L1 = 5 mm and D1 = 3.1 mm), or L1 ≤ 1.50 D1 or even L1 ≤ D1, where D1 is the diameter of the nozzle outlet. 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. For a nozzle outlet diameter of 3.1 mm, for example, axial distances L1 in the range of [2.0 - 2.6] mm are preferred. Accordingly, the following can preferably apply: 0.6 ≤ L1 / D1 ≤ 0.9. The exact values for L1 depend in particular on the operating pressure of the fuel used and can be optimized through testing.

[0028] Depending on the design, the distance L1 can also be zero or even negative. In the latter case, the nozzle-side tip of the impact body protrudes into the nozzle outlet orifice or dips into it.

[0029] To enable the most efficient atomization, the impact body should be designed with an elongated shape, as already mentioned. Therefore, one design proposes that the axial length L2 of the atomizing surface along the outflow direction be selected to be larger than the diameter D1 of the nozzle outlet opening. However, if, for example, spray angles > 90° are to be achieved, 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 2φ assumed by the impact body can thus be greater than 90°.

[0030] It can further 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 L1 between the nozzle-side tip of the impact body and the nozzle outlet opening.

[0031] The nozzle outlet opening can have a diameter D1 of at least D1 ≥ 0.5 mm, or even D1 ≥ 1.5 mm, to atomize a sufficient amount 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 deflector becomes increasingly less necessary.

[0032] 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.

[0033] A particularly preferred embodiment provides that the cone is designed as a right circular cone, in which case the longitudinal axis of the circular cone should 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 2φ of at least 5° or of at least 10°. Furthermore, depending on the application, it is preferable if the full opening angle 2φ is at most 135° (for example, if a spray angle of more than 90° is to be achieved) or at most 90° (for example, if spray angles of just above 90° are to be achieved) or even at most 70°, or even less than 45° (for example to produce a spray angle of only 35°).

[0034] When the longitudinal / rotational axis of the cone / circular cone / impact body and a 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.

[0035] 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 a respective angle of incidence for the fluid jet of at least 60°, and preferably of at most 85°, at points relative to the outflow direction (an angle of incidence of 0° would correspond to a steep perpendicular 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 flat.

[0036] 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 slender, elongated conical shape of the impact body. This has the decisive technical advantage of enabling high shear forces within the fluid jet and thus particularly efficient atomization. Due to 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. Thus, while inner portions of the fluid jet already hit the atomization surface and experience a reversal of direction there, the outer portions initially continue to fly unhindered at high speed.The resulting difference in the magnitude and direction of the respective velocity vectors in the near-axis and off-axis portions within the cross-sectional profile of the fluid jet emerging from the nozzle outlet opening then generates the desired high shear forces that efficiently atomize the fuel.

[0037] 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, the maximum wall thickness of the injection nozzle can be less than 2 mm, thus eliminating the need for a massive design, such as would be necessary at operating pressures of 1000 bar.

[0038] 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 that blocks a magnetic flux of the actuator and simultaneously 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 / pilot-controlled servo valves need to be used.

[0039] 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, a circumferential outer sealing ring can be provided on the injection nozzle, for example, 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.

[0040] The injector's injection nozzle can preferably be designed as a single-hole nozzle. In this case, the nozzle outlet opening thus forms the only opening of the injection nozzle from which fuel can exit. This approach differs from the multi-hole nozzles often used to date, in which multiple spray jets exit from several openings of the multi-hole nozzle. Since these jets generally diverge and overlap at a certain distance from the nozzle opening, these approaches often have the problem that individual spray jets, or more precisely the droplets contained therein, reunite, 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 exits from the single nozzle outlet opening (preferably aligned centrally with respect to the impact body), only produces a single diverging but homogeneous jet of very fine fuel droplets after impacting the impact body.

[0041] The nozzle valve mentioned above can have a valve seat, which can be annular, 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, thus closing the valve seat or the nozzle valve.

[0042] To enable a particularly rapid response of the injector, the invention provides for the valve seat to be designed as a conical nozzle seat. Such a design could possibly be considered a pintle nozzle. In any case, it is a single-hole nozzle.

[0043] 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, wherein the outlet channel in turn opens 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 velocity profile of the fuel as it exits 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 exiting fuel jet.

[0044] 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 created.

[0045] In contrast to so-called multi-hole nozzles, the nozzle outlet opening of the injector can have a diameter D1 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.

[0046] It can further be provided that for a ratio of a diameter D1 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: D1 ≥ 0.3 D4, preferably the following can apply: D1 ≥ 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.

[0047] 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 previously explained), wherein this closure body can preferably be actuated electromagnetically, namely by direct actuation with the aid of an electromagnetic actuator, as already mentioned. Thus, the nozzle valve can 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 controlled / 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 defined very precisely; however, typical switching times in application can be in the range 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.

[0048] 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.

[0049] To shorten the injector's switching times and also achieve homogenization of the fluid jet, one embodiment provides for the closure body to have or form a fuel supply channel that 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 prechamber, which is located upstream of the valve seat in the direction of fuel flow and can preferably be annular, is / remains evenly filled with fuel. Fuel can therefore be held in the prechamber in the immediate vicinity of the valve gap / valve seat to be opened, thus enabling virtually delay-free fuel injection. This is advantageous for achieving excellent short-term dynamics during atomization (which is a challenge with other atomization concepts such as swirl nozzles).

[0050] Such a valve design allows for rapid response or opening of the valve, even when operating at low fluid pressures of <20 bar. The prechamber 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 prechamber, the fuel, after passing through the valve opening in the area of the valve seat, can flow through a common outlet channel of the injection nozzle, which is located upstream of the nozzle outlet opening and preferably has a circular cross-section.In this way, the fuel can be ensured to exit 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.

[0051] 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, as the diameter D1 of the nozzle outlet opening. This enables a comparatively large volume flow of fuel to be released even with a small axial adjustment path of the closure body, resulting in the desired rapid actuation of the injector. Furthermore, the design of the aforementioned distributor enables the two fluid streams flowing through the open valve seat to combine into a homogeneous fluid stream, thus allowing a homogeneous fluid jet to emerge from the nozzle outlet opening of the injection nozzle.

[0052] 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. The 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°.

[0053] Especially when the injector is intended 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 for the atomization surface of the impact body to have a boundary that separates an axially forward region of the atomization surface from an axially rearward 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. To optimize atomization, it is now 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 θ for the fluid jet at each point in relation to the outflow direction, which 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.

[0054] 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.

[0055] In this context, the invention also proposes a corresponding 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 above.Accordingly, the injector can also include an electrical / electronic interface via which it can receive control signals for controlling / actuating the nozzle valve.

[0056] 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.

[0057] Thus, in a specific application of this method, for example, a methanol-diesel-air mixture can be generated / introduced into the combustion chamber, with a diesel injector injecting the diesel fuel directly into the combustion chamber, which in turn causes the diesel fuel to ignite. 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 timing 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.

[0058] 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, such as on ships) into a burner device of a heating device in order to be able to use methanol as fuel there as well.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 often cannot be cold-started). 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.

[0059] 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.

[0060] In the following description of various embodiments of the invention, elements that correspond in function are given the same reference numbers even if they have a different design or shape.

[0061] It shows / shows: the Fig. 1 to 4 a first possible embodiment of an injector according to the invention, wherein Fig. 1 a perspective view, Fig. 2 a partial longitudinal section and Fig. 3 a rear and Fig. 4 shows a front view of the injector, the Fig. 5 to 7 analog views of a second embodiment of an injector according to the invention, the Fig. 8 to 10 a third embodiment of an injector according to the invention, Fig. 11 a detail of the longitudinal section of the injector from Fig. 7, Fig. 12 a further enlarged view of the detail from Fig. 11 with a focus on the impact body according to the invention and finally Fig. 13 possible embodiments of impact bodies according to the invention with a stepped outer contour which defines a front first region and a rear second region of the atomization surface of the impact body.

[0062] The Fig. 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 fuel supply channel 7, which in the longitudinal section of Fig. 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 passes through channel arms 8 (distributor 10) formed in the closure body 6 into a prechamber 9, as can be seen particularly well in the detailed view of the Fig. 11, the details of a comparable injector 1 according to the Fig. 7. If fuel pressure is present on the inlet side of injector 1, prechamber 9 is always filled with fuel, even before nozzle valve 4 opens.

[0063] If a corresponding control signal is transmitted to the injector 1 via the control cable 21 (cf. Fig. 1), the locking body 6 can be moved against the restoring force of a return spring 30 (see Fig. 2) can be moved electromagnetically against the z-direction with the aid of an actuator 33, whereby the nozzle valve 4 of the injector 1 is directly actuated and thus opened. The shown flow 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 actuation 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 the Fig. 1 and Fig. 2 (see also the detailed view of the Fig. 11).

[0064] With the Fig. 2 and Fig. 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 corresponding control electronics), so that when the nozzle valve 4 is open, a homogeneous fluid jet of the fuel is discharged from the nozzle outlet opening 3 along the Fig. 2 and Fig. 11 illustrated outflow direction 5 (which corresponds to the longitudinal axis of the outlet channel 12). Subsequently, the fluid jet emerging from the nozzle outlet opening 3 traverses a free path 14 in air (compare Fig. 2 and Fig. 11) and then hits an atomizing surface 15 aligned obliquely to the outflow direction 5, which is Fig. 2 shown impact body 11. The impact body 11, which is designed in the form of a pointed and slender cone, is suspended by means of a bridge 16 freely in front of the nozzle outlet opening 3 and forms part of the injector 1, since the bridge 16, as in Fig. 1, is supported on the injection nozzle 2 by two legs 17.

[0065] In the second embodiment example according to the Fig. 5 to 7 as well as in the third embodiment according to the Fig. 8 to 10, the impact body 11 is designed the same way in each case, namely as a straight circular cone and thus as a rotationally symmetrical cone tapering towards the nozzle outlet opening 3. The outer surface of this circular cone forms the atomization surface 15. In order to generate high shear forces when the fuel impacts the atomization surface 15, this is gently inclined to the outflow direction 5. Accordingly, in the design of the impact body 11 shown in the figures, the atomization surface 15 is arranged within an imaginary circular cone, the tip 18 of which points towards the nozzle outlet opening 3 and whose full opening angle 2φ is less than 40° (cf. also the detailed illustration according to Fig. 11). How to Fig. 11 (which shows a detailed view of the Fig. As can be seen from the dotted lines (see Figure 7), the spray angle 32, i.e., the angular range at which the fuel droplets exit the injector 1, is somewhat larger. Depending on the requirements of the specific application, however, the inventive concept can also generate spray angles > 90°, in which case the opening angle 2φ of the impact body 11 can be selected to be correspondingly larger.

[0066] In the detailed view of the Fig. 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 D1 of the nozzle outlet opening 3, so that the entire fluid jet which emerges from the nozzle outlet opening 3 actually impacts the atomization surface 15.

[0067] In the first example of Fig. 1 to 4, the impact body 11 is suspended from a two-legged bridge 16, as can be seen particularly in the front view of the Fig. 4 clearly visible. In the example of the Fig. 8-10, 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 prone to vibration. In both designs, 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 the free space almost unhindered. This is because, especially in Fig. 4 clearly shows that only very narrow angular ranges in the xy-radial plane are blocked by bridge 16 (namely at 12 o'clock and 6 o'clock positions), while the remaining angular range of more than 300° is kept free (compare the dotted block arrows). The same applies to the Fig. 9, where three respective areas are kept clear, which, when added together, also amount to more than 300°. In the cleared angular areas, the fuel can thus exit the injector 1 after atomization unhindered and without contact with components of the injector 1.

[0068] This also applies to the designs according to the second and third design examples, where, as in Fig. 5 and in Fig. 8, a pot 27 is designed as part of the injection nozzle 2, which surrounds the impact body 11 in a ring and protects it from damage. Especially in the Fig. 7 and Fig. 10 it is clearly visible that the front edge 20 of the pot 27 is set back so far from the bridge 16, opposite the outflow direction 5, that here too the fuel mist created at the impact body 11 can be released into the room largely unhindered. Fig. 11 of the extension of the atomizing surface 15 in the direction of the outflow direction 5, as shown by the two inner dot-dash lines, in conjunction with the corresponding frontal view of the Fig. 6 clearly understand that in this example too, an angular range of more than 300° in total, related to the Fig. 6 with the block arrows there illustrated circumferential angle in the xy radial plane, is kept free.

[0069] Using the outer dash-dot lines in Fig. 11 further shows 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 with the injector 1 without fuel being able to directly precipitate on the inner wall of the pot 27.

[0070] In the detailed views of the Fig. 11 and Fig. 12, it is also clearly visible that the outlet channel 12 is kept free along its entire length L3, so that the fluid jet emerging from the nozzle outlet opening 3 has a circular disk-shaped cross-section. To enable efficient atomization, the axial length L2, as can be clearly seen in Fig. 11 recognizes, is chosen to be significantly larger than, for example, the diameter D1 of the nozzle outlet opening 3 but also larger than the axial length L3 of the outlet channel 12. The axial distance L1 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 just smaller than the diameter D1 and also smaller than the axial length L2 of the atomization surface 15.

[0071] In the illustrated rotationally symmetric design of the impact body 11, the cross-section increases in the outflow direction 5. However, depending on the application, a rotationally symmetric shape may not necessarily be required. For efficient atomization, it is more important to achieve comparatively large angles of incidence θ for the fluid jet by appropriately aligning the atomizing surface 15.

[0072] As the Fig. 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 continuously, so that the angle of incidence θ does not change suddenly, but continuously. In the left variant a), the atomizing surface 15 in the front region 28 is aligned flatter to the outflow direction 5 than in the rear region 29; in the second variant b), which is shown on the right in Fig. 13 and is preferred over variant a), it is just the other way around.

[0073] In Fig. 12, for example, it can be clearly seen that, due to the slender shape of the circular cone that defines / delimits the atomization surface 15 of the impact body 11, (point by point) a respective surface normal (illustrated as a dashed line) of the atomization surface 15 to the outflow direction 5 forms a respective angle of incidence θ 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 atomization surface 15 significantly later than the radially inner regions. Correspondingly high shear forces result as soon as the inner regions of the fluid jet impact the atomization surface 15, while the outer regions of the fluid jet continue to fly in the outflow direction 5.

[0074] It is also worth mentioning with regard to the design of the nozzle valve 4 that the valve seat 13 is designed as a conical seat nozzle seat, because the closure body 6 is immersed in the already described conical seat 19, the inlet contour of which forms the valve seat 13 of the nozzle valve 4. However, the closure body 6 is only partially immersed, but not completely, in 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. Fig.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 D1 of the nozzle outlet opening 3. Accordingly, even with only minimal opening of the nozzle valve 4, a considerable 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.

[0075] 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. List of reference symbols 1 fuel injector 2 injection nozzles 3 Nozzle outlet opening (formed at the end of 2) 4 Nozzle valve (is upstream of 3, controls the flow of fuel through 2 / 3) 5 Outflow direction (direction in which the fuel exits from 3) 6 locking bodies (locks 13) 7 Fuel supply channel (designed in 6) 8 channel arm (branched from 7 via a 10) 9 Antechamber 10 distributors 11 impact bodies 12 Outlet channel (from 2, flows into 3; is downstream of 13 in the fuel flow direction) 13 Valve seat (closed by 6) 14 free paths (between 3 and 11) 15 atomization area 16 Bridge (supports 11) 17 Leg (of 16, supports 16 on 2) 18 tips (of 11, aligned to 3 on the nozzle side) 19 Conical seat 20 Rand (out of 27) 21 control cables (for controlling ¼) 22 Fluid connection 23 Magnet 24 Flux blocking sleeve (blocks a magnetic flux from 33 and fluidically seals 33 against the fuel) 25 anchors 26 (external) seal 27 pot 28 front area (of 15) 29 rear area (of 15) 30 return spring 31 border (between 28 and 29) 32 spray angles 33 electromagnetic actuator 34 Fluid jet Design parameters D1 Diameter of the nozzle outlet opening D2 smallest diameter of the valve seat D3 maximum diameter filled by the atomization surface in the radial plane D4 Diameter of the fuel supply channel L1 free axial distance L1 along 5 between a nozzle-side tip of 11 and 3 L2 axial length of 15 along 5 L3 axial length of 12 L4 axial length of 19 θ angle of incidence (from 34 to surface of 11) 2φ full aperture angle (of 11)

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 by , - 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 injector (1) according to claim 1, 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 2φ of which is at most 130°, at most 60°, at most 45° or at most 35°. [3] Fuel injector (1) according to one of the preceding claims, wherein a maximum diameter D3, which the atomizing surface (15) fills in a radial plane running perpendicular to the outflow direction (5), is selected to be at least so large that: D3 ≥ 0.50 D1, or D3 ≥ 0.85 D1 or D3 ≥ 0.90 D1 or even D3 ≥ D1, with D1 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 injector (1) according to one of the preceding claims, wherein the impact body (11) is suspended such that an extension of its atomizing 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), - in particular so that fuel atomized on the impact body (11) can escape from the same in the free angular areas unhindered 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 suspended freely above the nozzle outlet opening (3) on one leg or by means of a bridge (16) having two legs (17a, 17b), preferably by means of a bridge (16) having three legs (17a, 17b, 17c). [7] Fuel injector (1) according to one of the preceding claims, wherein an axial distance L1 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: L1 ≤ 1.75 D1, or L1 ≤ 1.50 D1 or even L1 ≤ D1, with D1 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 D1 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 forms the atomization surface (15), - preferably wherein the cone is designed as a right circular cone, particularly preferably with a full opening angle 2φ of 2φ ≥ 5°, in particular of 2φ ≥ 10°, preferably and of 2φ ≤ 130°, in particular of 2φ ≤ 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 θ 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 fuel fluid pressures 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 D1 of at least D1 ≥ 0.5 mm, or even D1 ≥ 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 injector (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 (4) is closed, a preferably annular pre-chamber (9) upstream of the valve seat (13) in the direction of flow of the fuel is filled with fuel. [15] Fuel injector (1) according to one of the preceding claims, wherein the atomizing surface (15) has a preferably circumferential boundary (31), in particular in the form of a step or rounding, 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 area (28) a) flat or b) is oriented more steeply to the outflow direction (5) than in the rear area (29), - in particular so that a respective surface normal of the atomizing surface (15) forms a respective angle of incidence θ for the fluid jet pointwise to the outflow direction (5), which angle of incidence in the front region (28), preferably always, a) greater than or equal to or b) is smaller than in the rear area (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 the flow of a fuel-air mixture from the intake manifold into the combustion chamber can be controlled, characterized by , - 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] Method for operating an internal combustion engine designed according to the preceding claim 16, - wherein liquid fuel, in particular methanol, is finely atomised in the intake manifold by means of the fuel injector (1) in order to then pass through the inlet valve 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 claims 1 to 15, - wherein the fuel injector (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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