Nozzle attachment assembly, system consisting of a flat spray nozzle and nozzle attachment assembly, and method for spray preservation

Abstract

The invention relates to a nozzle attachment assembly (10) comprising a connection element (12) having a coupling point (18), located on an end face (16), for receiving a flat spray nozzle (20), a spray-preservation element (14) connecting to the connection element in an axial extension direction (24) of the nozzle attachment assembly (10), and the spray-preservation element comprising an outlet opening (28) on an outlet face (26) facing away from the end face, which outlet opening is fluid-conductingly connected to the coupling point by the interior of the nozzle attachment assembly, the fluid-conducting connection being in the form of an expansion zone (30) which, in a first plane, is delimited perpendicularly to the axial extension direction by cover walls (34, 36) having a spacing h, and which, in a second plane which is perpendicular to the first plane, is delimited by sidewalls (40, 42) so that the expansion zone reproduces a spray geometry of the of the receivable flat spray nozzle in such a way that a fluid spray formed by this spray geometry inside the expansion zone is uninterruptedly surrounded by a circumferential gap in a radial direction (46), and the connection element and / or the spray-preservation element comprising at least one gas-inlet opening (50) which opens into the expansion zone. The invention also relates to a system having such a nozzle attachment assembly, and to a method for spray preservation.

Description

[0001] NOZZLE ATTACHMENT ASSEMBLY, SYSTEM CONSISTING OF FLAT JET NOZZLE AND NOZZLE ATTACHMENT ASSEMBLY AND METHOD FOR JET PRESERVATION

[0002] The present invention relates to a nozzle attachment assembly, a system comprising a flat jet nozzle and a nozzle attachment assembly, and a method for preserving the jet of a liquid jet emerging from a flat jet nozzle.

[0003] Liquid-powered high-pressure cleaners are well-known and are used, for example, for cleaning dirty surfaces or removing varnish and paint residue from surfaces. For this purpose, a high-pressure compressor pumps liquid under high pressure to an outlet nozzle, from which the liquid exits the high-pressure cleaner. The jet is shaped in a way that is significantly influenced by the nozzle. The liquid is often water or water mixed with a cleaning agent. Starting from the nozzle, the liquid jet then moves towards the surface to be cleaned, with the kinetic energy stored in the liquid particles of the liquid jet exerting its cleaning effect upon impact with the surface to be cleaned.A flat spray nozzle typically consists of a housing that can be connected to a pressure washer or other high-pressure source. Within the housing is an opening shaped to force the liquid jet into a flat, fan-shaped pattern. This is achieved by building up pressure within the nozzle and then directing it through a narrow, elongated opening called the flat spray gap. This shapes the liquid into a continuous, even flat jet. As the liquid approaches a nozzle outlet opening, the diameter of the liquid stream is reduced. This greatly accelerates the liquid, exiting the nozzle at high speed to create the high-pressure jet.The problem here is that as the distance between the nozzle and the surface to be cleaned increases, the transferable kinetic energy and thus the cleaning performance of the liquid jet decreases. This effect is already noticeable when cleaning in air, because air, despite its comparatively low density, impedes the movement of the liquid jet and leads to a noticeable dispersion of the liquid jet after just a few centimeters. This is particularly true, however, when cleaning is to take place in a significantly denser / more viscous medium. If the liquid jet is used underwater to clean a surface, for example, a noticeable reduction in cleaning performance can be seen even after the liquid jet has to travel significantly shorter distances to the surface to be cleaned (compared to air).

[0004] To date, this problem has been solved by regularly increasing the kinetic energy stored in the water jet by using more powerful compressors to provide the required cleaning performance in each specific application. However, this approach encounters economic and technical limitations.

[0005] The present invention is based on the object of increasing the cleaning performance of a liquid-operated high-pressure cleaning system in a cost-effective and energy-efficient manner.

[0006] This object is achieved by means of a nozzle attachment assembly having the features of independent claim 1 and by means of a system having the features of independent claim 11. Furthermore, this object is also achieved by a method having the features of independent claim 14.

[0007] Advantageous embodiments and further developments emerge from the dependent claims. A nozzle attachment assembly is described, comprising a connecting element with a coupling point arranged on a front side for receiving a flat jet nozzle of a liquid-operated high-pressure cleaner, wherein a jet retention element is connected to the connecting element along an axial extension direction of the nozzle attachment assembly, wherein the jet retention element comprises an outlet opening on an outlet side facing away from the front side, which is in fluid-conducting connection through the interior of the nozzle attachment assembly with the coupling point, wherein the fluid-conducting connection is formed as an expansion zone which is delimited in a first plane perpendicular to the axial extension direction by cover walls which have a distance h and which is delimited in a second plane perpendicular to the first plane by side walls.so that the expansion zone as a whole replicates a jet geometry of the accommodateable flat jet nozzle such that a liquid jet formed with this jet geometry is continuously surrounded by a circumferential gap within the expansion zone in a radial direction perpendicular to the axial extension direction, and wherein the connecting element and / or the jet retention element has at least one gas inlet opening that opens into the expansion zone. The at least one gas inlet opening can, as required, have a filter or shielding device to prevent the penetration of foreign or dirt particles that could negatively influence gas intake. The outlet opening can be substantially rectangular.However, they can also have slightly rounded corners. In particular, the two short sides can also be slightly curved. The ratio of the short sides to the long sides of the outlet opening can, for example, be at least 1:10. The expansion zone can accompany the expansion of the liquid jet, for example, by a factor of 20 (in jet width) along the axial direction of extension, i.e., from the outlet of the flat jet nozzle to the outlet opening of the nozzle attachment assembly.

[0008] The distance h can be constant or at least essentially constant. However, it is also possible for the distance h between the two cover walls to increase or decrease in the axial direction of extension as seen from the flat nozzle, wherein the increase and decrease can be identified with an opening or closing angle. In this context, the increase or decrease can in particular be uniform / uniform, so that a plane of symmetry can be found in which the axial direction of extension can run. The opening or closing angle can preferably be constant. By varying the distance h in this way or by providing an opening / closing angle, additional jet shaping can be brought about in the expansion zone if required, since these changes initially bring about a change in the uniformity of the gas flow and, as a direct consequence, in turn a change in the jet shaping.

[0009] With the help of this nozzle attachment assembly, when coupled to the flat jet nozzle and the liquid jet emerging from the flat jet nozzle, in its intended geometry as described, resembles the dimensions of the expansion zone in the nozzle attachment assembly, the jet geometry of the liquid jet can be advantageously preserved over a greater distance after exiting the flat jet nozzle and passing through the jet retention element of the nozzle attachment assembly. The term "distance" or "distance" refers, for example, to the distance from the flat nozzle at which the liquid jet is generated by the flat nozzle, at which the "liquid" is currently being viewed. In particular, the typical scattering / atomization of the liquid jet on the medium, such as water or air, through which it passes can be greatly reduced.This effect is achieved with the help of the gas, which can enter or is sucked into the expansion zone via the gas inlet opening. Due to its design, the liquid jet essentially does not touch the expansion zone as it passes through the jet containment element and is circumferentially spaced evenly in a radial direction from the cover and side walls bordering the expansion zone, so that a circumferential gap of essentially constant width is created between the liquid jet and an expansion zone wall. The liquid jet flowing through the expansion zone sucks in gas through the gas inlet opening according to the principle of a water jet pump. This gas enters the expansion zone and is entrained by the liquid jet.A uniform gas flow forms around the liquid jet in the gap between the surface of the liquid jet and the top and side walls of the expansion zone. This gas flow completely envelops the liquid jet even after it exits the outlet opening and advantageously delays the dispersion of the formed liquid jet after it exits the outlet opening. The generated uniform gas flow thus prevents or delays unwanted atomization or "thickening" of the flat jet generated by the flat jet nozzle during the expansion of the flat jet in the nozzle attachment assembly. The term "uniform" can be understood, for example, but is not limited to, a gas flow that has at least some properties of a laminar gas flow or a vortex-free gas flow.Due to the operating principle, the sucked-in gas is not sucked into the liquid jet, but accelerated on its surface in the direction of liquid flow. Although part of the kinetic energy contained in the liquid jet is used to suck in the gas, and the liquid jet is therefore even somewhat slower when it flows out of the nozzle attachment assembly (compared to a (structurally identical) system without a nozzle attachment assembly), a higher cleaning performance is achieved due to the better concentration of the liquid jet (flat jet with reduced thickness and the same width) on the surface to be cleaned. A portion of the kinetic energy extracted from the liquid jet remains in the liquid jet in the form of (waste) heat. Experimentally, a measured warming of the liquid jet by 1 to 2 °C was observed in the test system used with the described nozzle attachment assembly.This temperature increase, in turn, benefits the increased cleaning performance, as warmer fluids generally clean better than colder ones. By using the nozzle attachment assembly described above, energy and fluid savings of 50% can be achieved compared to a conventional system without such an assembly. At the same time, the significantly increased cleaning performance also saves a significant amount of working time.

[0010] The drawn-in gas can be air or another gas, for example; it is conceivable to draw in steam, for example, to further increase cleaning performance. Within the nozzle attachment assembly, more precisely as it passes through the expansion zone, the flat jet generated by the nozzle is corrected in its shape by the drawn-in air, which forms the uniform boundary layer, without the flat jet essentially touching the nozzle attachment assembly. In this process, undesirable deviations from the intended jet geometry generated by the flat jet nozzle are compensated for / reduced. The corrected flat jet is not affected in its developing width, but remains more compact in its "thickness" and at the same time more uniform across its width. This process could also be referred to as "recompression."This correction of the jet geometry within the expansion zone of the nozzle assembly is the essential function that contributes the most to the increased cleaning performance. The surprising effect is that the gas remains between the different flow velocities of the surrounding medium / wall of the nozzle assembly and the liquid jet, forming a stable gas cushion that optimally separates and creates a uniform gas flow. Therefore, the energy loss of the flat jet during its expansion is reduced, and the flat jet remains more concentrated / compact. The uniform gas flow that develops on the surface of the liquid jet also represents a type of gas curtain, further shielding the liquid jet from the scattering effect of the surrounding medium after it exits the nozzle assembly. The gas curtain can also be considered a type of separating curtain.In the uniform boundary layer between the air and water jets, the difference in air and water speed can cause the liquid droplets to rotate, detaching from the liquid jet in a mist-like manner. When such a rotating liquid droplet impacts the surface to be cleaned, it creates an increased cleaning effect by generating local shearing forces on the dirt to be removed.

[0011] The nozzle attachment assembly allows for more efficient high-pressure cleaning with all other parameters remaining the same. Especially underwater, a cleaning performance increase of approximately 500% can be achieved compared to a system without any jet-shaping assembly. The increased cleaning performance correlates with the length of the nozzle attachment assembly in the axial direction. The longer the flat jet is guided in its expansion within the nozzle attachment assembly, the more powerful the flat jet is compared to a conventionally expanding flat jet. The nozzle attachment assembly can be designed as an add-on accessory for an existing high-pressure cleaning system with a flat jet nozzle.

[0012] The rectangular, pyramid-shaped or truncated pyramid-shaped flat jet is separated from the surrounding medium during its initial propagation by the nozzle attachment assembly. Additionally, gas is entrained / sucked along the edge of the flat jet, which is drawn in from outside. This prevents the medium from penetrating the nozzle attachment assembly. The drawn-in gas creates a physical effect that positively influences the liquid jet and its further spatial propagation within the medium. Furthermore, the uniform gas flow upon exiting the nozzle attachment assembly forms a gas cushion, massively reducing the effective average density of a given volume of space, which includes both liquid, particularly water, and gas, such as air. This reduction occurs particularly at the edge of the liquid jet.This further increases cleaning performance, as the high-pressure jet is slowed down less by the reduced density. A further effect of the nozzle attachment assembly described is that the highly uniform, accelerated gliding air generated during operation between the flat jet and the side and / or top wall is significantly slowed down again upon exiting the nozzle attachment assembly, undergoing a spatial expansion. This also causes the flat jet to remain more compact for longer than usual, even outside the nozzle attachment assembly, than with unprotected expansion. A more compact flat jet inevitably means better cleaning performance. The term "more compact flat jet" refers primarily to the vertical extension or thickness of the flat jet and only to a very limited extent to the width of the flat jet.

[0013] The formed liquid jet therefore remains "focused" with the intended jet geometry for longer, so that less of the kinetic energy contained in the liquid jet is transferred to the surrounding medium, for example air or water, while the liquid jet, starting from the outlet opening, impacts a surface to be cleaned.

[0014] Ultimately, this allows more energy per area to be transferred to the surface to be cleaned with the same power applied to the liquid jet. Alternatively, a system that uses the nozzle attachment assembly can achieve the same cleaning effect with less effort as a system without the nozzle attachment assembly. Accordingly, the described nozzle attachment assembly makes a system comprising the flat jet nozzle and the attached nozzle attachment assembly more powerful, with all other parameters remaining the same, or alternatively, more efficient in terms of the achievable cleaning effect while maintaining the same cleaning effect. Mixtures between these two extremes can also be adjusted, whereby a trade-off exists between efficiency and cleaning performance.With the nozzle attachment assembly, it is no longer possible to get too close to a cleaning object and damage it with an overly powerful jet, as the dimensions of the nozzle attachment assembly already ensure sufficient physical distance. Furthermore, the described nozzle attachment assembly also reduces the recoil that a user of a high-pressure cleaning system has to absorb when guiding the flat nozzle.

[0015] Furthermore, an additional gas supply via a gas pressure generator, such as a compressed air generator, can be dispensed with if necessary. The nozzle attachment assembly described is, by design, "self-priming" for the required gas volume. Accordingly, gas supply systems can be dispensed with entirely.

[0016] The term "coupling point" used in these documents can be used to refer to the location of any fastening device known to those skilled in the art, which, for example, secures the nozzle attachment assembly to the flat jet nozzle in a force-fitting or form-fitting manner. The nozzle attachment assembly can be secured to the fastening point in a force-fitting or form-fitting manner using the fastening device. Form-fitting fastening can be achieved, for example, with a bayonet lock. Force-fitting fastening can be achieved, for example, with a clamp lock. More complex fastening mechanisms are possible.In the context of the present application documents, the term "flat jet nozzle" refers to a nozzle that forms the supplied liquid into a liquid jet, which, at least in the vicinity of the flat jet nozzle, has a fixed jet geometry determined by the nozzle. In a flat jet nozzle, this jet geometry is defined by a fan-shaped jet shape, with the formed jet spreading along the axial direction of extension, which coincides with the flow direction of the liquid.The flat jet formed by the nozzle has a thickness that is as constant as possible in the first plane perpendicular to the axial direction of extension, and lateral edge regions in the second plane perpendicular to the first plane, which, starting from a nozzle exit point, can be described by an opening angle, so that the edge regions of the formed jet diverge evenly in the axial direction of extension with increasing distance from the nozzle exit opening. The axial direction of extension is therefore the direction in which the flat jet nozzle forms the flat jet and, at the same time, the direction in which the nozzle attachment assembly primarily extends.

[0017] The flat jet nozzle is a special nozzle that shapes the liquid jet into a flat and wide, rectangular, pyramidal, or truncated pyramid shape. A typical flat jet nozzle produces a flat liquid jet that is rectangular in front view and expands. The expansion is uniform and occurs across the width with an angle of at least 15°. The flat jet nozzle is usually designed to create a specific angle between the two outer edges of the flat jet, which can vary depending on the application and model (at least 15° and a maximum of 145° opening angle across the width). Geometrically, a flat jet with an opening angle of at least 15° describes a concentrated liquid jet that emerges in the shape of a fan with an opening angle of at least 15 degrees across the width (or area).The flat jet is thus wider than a (focused) point jet, but narrower than a point jet with a larger lateral opening angle, whereby the flat jet is symmetrical in width. In geometry, such a shape is also described as a rectangular pyramid. In the context of the present application documents, the term "flat jet" therefore refers to a jet that is forced into a flat, wide shape with a fan-shaped spread. Generally, a flat jet is defined as one with an opening angle of 15 degrees or more.

[0018] The flat jet formed by the flat jet nozzle, for example, has a thickness of around 0.6 mm when it exits the nozzle. After a distance of 200 mm, the flat jet formed by the flat jet nozzle already has a thickness of around 4 mm. The jet therefore diverges. The flat jet formed by the same flat jet nozzle, for example, after flowing through the nozzle attachment assembly and having its shape corrected, only has a thickness of around 2 mm after traveling the same distance of 200 mm, whereby a compressor power of around 2.8 kW is assumed in all cases. The nozzle attachment assembly can therefore significantly improve the compactness of the jet geometry. In other words, the jet geometry actually achieved by the flat nozzle is improved towards the ideal intended jet geometry when the flat nozzle is used together with the nozzle attachment assembly.When the nozzle attachment assembly is used, a significant amount of gas is drawn in through the gas inlet opening by the flat jet, with just over 90 liters per minute being measured experimentally in one tested system.

[0019] To improve handling, the nozzle attachment assembly may have rollers on its outlet side to assist in even guidance over the surface to be cleaned.

[0020] The connecting element and the jet containment element can be integrally connected to one another, in particular formed as a single piece. It is conceivable that one element is firmly molded onto the other element, or that both elements are manufactured separately and then firmly connected to one another. The term "firmly connected" can be understood, for example, as detachable, non-destructively detachable, or as materially bonded. Materially bonded connections include, in particular, fusion, welding, soldering, and gluing. The optionally fan-shaped expansion zone can be recognized in particular as the "negative" of the formed flat jet, so that the distance h between the formed flat jet and the side walls and cover walls delimiting the expansion zone can be considered essentially constant.In the context of the present application documents, the radial direction can be understood as the usual radial direction in cylindrical coordinates, whereby the axial extension direction in cylindrical coordinates corresponds to the usual Z-axis and the radial direction in every position is perpendicular to the axial extension direction and is additionally defined by a rotation angle <p (in Zylinderkoordinaten) um die axiale Erstreckungsrichtung gedreht werden kann. Die radiale Richtung weist dabei immer von der axialen Erstreckungsrichtung fort.

[0021] Usefully, it can be provided that the at least one gas inlet opening is closable or adjustable. The closability of the at least one gas inlet opening can be achieved, for example, with the aid of a suitable closure flap or a suitable closure mechanism, wherein, in particular, a partial closure of the at least one gas inlet opening can also be achieved, for example, by means of an adjustable slide control. Partial closure can therefore be associated with the term "adjustable." By closing or partially closing the at least one gas inlet opening, the amount of gas sucked into the expansion zone by the liquid jet can be influenced while otherwise keeping the parameters constant, thus enabling simple control of the cleaning performance by adjusting the gas quantity.When the nozzle attachment assembly is used in an underwater environment, the intensity of the formed gas curtain is also reduced, resulting in a visually noticeable effect due to the reduced amount of gas drawn in. This ultimately results in fewer gas bubbles enveloping the formed liquid jet after it exits the nozzle attachment assembly. The gas bubbles and the underwater environment often have significantly different calculation indices and, due to the resulting boundary layers, form an opaque curtain around the liquid jet, which also obstructs direct vision of the impact point on the surface to be cleaned. By sufficiently reducing the number of gas bubbles, improved visibility of the surface to be cleaned can be achieved if necessary.Furthermore, by closing the gas inlet opening, the air cushion can be replaced by a vacuum, allowing the nozzle attachment assembly to adhere to the surface to be cleaned due to the Bernoulli effect. Furthermore, it can be provided that the at least one gas inlet opening opens into the expansion zone at at least two separate openings, with at least one opening being provided on each cover wall. By providing two separate openings at which the gas inlet opening opens into the expansion zone, gas can be drawn in from each "side" of the formed liquid jet. This creates a uniform gas flow on each of the two opposite flat sides of the formed liquid jet, so that the formed liquid jet is evenly enveloped by the uniform gas flow in essential parts of the expansion zone, namely the two flat sides.The size and shape of the at least two separate openings and their connection to the at least one gas inlet opening can be designed such that equal gas volumes are drawn in per unit of time on opposite sides, and that the uniform gas flow formed, which can also be regarded as a gas curtain, reaches equal thicknesses on the two flat sides of the liquid jet near the outlet opening. The at least two separate openings are thus designed in a special way with respect to one another in terms of their respective sizes, shapes, and connections to the at least one gas inlet opening, so that the same amount of gas can be drawn in to reshape the already formed flat jet in the expansion zone, thus maintaining the intended shape for longer.Two of the at least two openings can be arranged on the edge of the cover sides facing the flat jet nozzle and, if necessary, "notch" the cover side there. The openings can, for example, be positioned opposite each other, whereby this positioning can then, in particular, exhibit a certain symmetry, for example, mirror symmetry along the axial direction of extension.

[0022] In this context, it can advantageously be provided that the at least one gas inlet opening opens into the expansion zone at at least four openings, with at least one opening being provided on each top wall and furthermore at least one opening being provided on each side wall. In this way, the liquid jet formed by the flat jet nozzle can be shaped in a supportive manner on its flat sides. It can be provided that the at least four openings are separate openings. It is also possible here for two openings arranged on the opposite side walls to be arranged symmetrically to one another in a particular way.

[0023] Furthermore, the side walls can diverge in the axial direction of extension, so that the expansion zone expands in a fan shape. This allows the expansion zone to replicate the jet geometry even more precisely, resulting in a more uniform width of the circumferential gap between the liquid jet and the surrounding walls along the axial direction of extension. This improves the lateral spread of the flat jet, allowing a somewhat wider flat jet to be generated by the same flat jet nozzle, which in turn can accelerate the cleaning of a surface, as the jet needs to be moved less frequently / far to cover the entire area.

[0024] It can also be provided that at least one structuring projection is provided on each of the opposing cover walls, which locally reduces the distance h between the cover walls. The at least one projection creates a "floor effect," which, with suitable design / shaping, can be used to homogenize the flat jet across its width and thickness. The generated positive or negative floor effect creates an additional pressure gradient in the passing gas, which in turn attracts or repels liquid from the liquid jet. In this way, for example, a flat jet that is particularly homogeneous across its entire width can be generated experimentally, which accordingly also provides a particularly uniform cleaning performance. The exact position and shape of the at least one projection on the cover walls can be varied as required.In particular, it is also possible to arrange several projections at different locations on the opposing cover walls simultaneously. For example, it can be provided that projections on the opposing cover walls are designed symmetrically to each other in pairs and, for example, have the same dimensions. Thus, there can always be a symmetrical, identical "counterpart" (a corresponding projection on the opposite cover wall). To clarify, it should be mentioned at this point that every conventional flat jet nozzle, due to its design, usually produces an uneven flat jet with an inhomogeneous power distribution across its width. Thus, more power is usually transferred to a target area in the center of the jet than in the two edge areas, since more fluid flows in the center of the jet despite the flat jet shape.This problem is solved by at least one structuring projection, as this can guide liquid from the center of the jet to the edge areas "contactlessly" during the expansion of the flat jet.

[0025] In this context, it can additionally be provided that the projections are adjustable in their orientation within the expansion zone. In the context of these application documents, the term "orientation" can be understood as both their (average) height relative to the remaining unstructured cover wall and an angular adjustment of the individual surfaces of the projections (angle of incidence). Such adjustability can be achieved, for example, by means of one or more adjusting means, such as screws, which are particularly accessible from the outside. The adjusting means can, for example, move a particularly flat surface of the projections facing the expansion zone continuously or in a stepped manner.

[0026] Usefully, it can be provided that openings provided on the opposing cover and / or side walls are arranged symmetrically in pairs. By arranging the openings provided on the opposing cover and / or side walls in pairs, the centering of the formed liquid jet inside the nozzle attachment assembly is promoted or supported by the sucked-in gas, so that small undesirable or unintentional angular deviations between the axial extension direction of the nozzle attachment assembly and the outflow direction of the liquid jet from the flat jet nozzle are compensated or at least reduced.Furthermore, by arranging the openings symmetrically on the respective opposite top and / or side walls, the dispersion of the liquid jet can be counteracted evenly and in particular from all sides.

[0027] It can also be provided that several openings are provided on each of the opposing cover walls in the axial direction of extension, the respective width of which increases with increasing distance from the connecting element. By providing several openings on the opposing cover walls in the axial direction of extension, the wide sides of the liquid jet formed by the flat jet nozzle can be influenced several times in a shape-supporting manner, so that the compactness and stability of the formed liquid jet is further improved as it exits the nozzle attachment assembly at the outlet opening. The additional air inlets in the expansion zone prevent, in particular, the formation of a high negative pressure, which steadily increases along the axial direction of extension.Such a high, increasing negative pressure would, in an expansion zone extending in the axial direction, "suck" the liquid jet against the cover walls, thus causing "scouring." This scouring would, in turn, trigger turbulence in the flat jet, which would result in faster dispersion after exiting the expansion zone. An additional side effect of the additional openings is that the jet exiting the expansion zone is only about half as thick (in the direction between the two cover walls) as it would be without the nozzle attachment assembly. This ultimately results in even better cleaning performance, as the emerging flat jet is even more focused. By increasing the area of ​​the individual openings with increasing distance from the connecting element, the increasing width of the fanning out flat jet can be accommodated.By providing several additional openings on the opposing deck walls, a significant further increase in cleaning performance can be achieved. For example, with a jet width of 70 mm (at the nozzle outlet), a cleaning performance increase of at least 50% can be achieved when used with air as the ambient medium. With the additional openings, a cleaning performance increase of at least 1000% can be achieved in underwater applications (compared to a system without any nozzle attachment assembly). By adding or removing openings at specific locations, i.e., by positioning them specifically along the axial extension, an uneven water jet power distribution caused by the flat jet nozzle can be "homogenized," so that when the flat jet exits, the cleaning performance is more uniform across the entire extent, i.e., the width, of the flat jet.The optimal positioning of the openings for a special flat jet nozzle can, for example, be determined experimentally.

[0028] Usefully, it can also be provided that gas inlet openings are provided on the connection element. By providing gas inlet openings on the connection element, for example, the gas supply can be arranged in direct proximity to the coupling point, so that the gas supply can be arranged as far away as possible from the outlet opening, in particular on the front side of the connection element. This reduces the risk of liquid from the liquid jet emerging from the nozzle attachment assembly splashing back through the gas inlet openings after impacting a surface to be cleaned and negatively affecting the function of the nozzle attachment assembly. Furthermore, in an underwater application, the gas supply via the gas inlet openings can advantageously be combined with the attachment of the flat jet nozzle to the nozzle attachment assembly.

[0029] By arranging gas inlet openings on the jet containment element, the intake paths from the gas inlet openings to the openings in the expansion zone can be made short, which can improve the suction effect of the formed liquid jet in the expansion zone. In this way, the intensity of the formed gas curtain can be increased.

[0030] Furthermore, it can be provided that the connecting element comprises an elastic material. The elastic material allows for easy attachment of the nozzle attachment assembly to the flat jet nozzle, for example, by the nozzle attachment assembly having a circumferential elastic sealing lip that can be pushed over the flat jet nozzle counter to the axial direction of extension, thereby clamping and sealing the flat jet nozzle to the nozzle attachment assembly at its coupling point.

[0031] Furthermore, it can be provided that a gas supply line can be connected to the at least one gas inlet opening. In this way, even in an underwater application, gas can be provided that can be sucked in at the at least one gas inlet opening and can be sucked into the expansion zone by means of the formed liquid jet. It is also possible for gas to be actively conveyed towards the at least one gas inlet opening via the connectable gas supply line, for example by means of a cooling fan of a compressor of the liquid-powered high-pressure cleaner. This can be particularly advantageous with a longer gas supply line, since the suction effect of the liquid jet is limited and, with a longer gas supply line, may not be sufficient to suck in a sufficient quantity of gas without assistance.Usefully, it can be provided that the jet containment element can be modularly assembled from several individual elements, wherein the several individual elements can be connected to one another in the axial direction of extension. In this way, a length of the jet containment element in the axial direction of extension can be adapted depending on the application, wherein it should be noted in this regard that an extension of the jet containment element in the axial direction of extension always also extends the expansion zone in this direction, so that the liquid jet is then guided over a longer distance and correctively reshaped by means of the uniform gas layer. It can be provided that the modularly connectable individual elements differ from one another, in particular in their respective dimensions, and in this respect a fixed sequence must be observed when connecting them to one another.

[0032] Also described is a system comprising a flat jet nozzle configured to form supplied liquid into a flat jet with a jet geometry, and a nozzle attachment assembly adapted to this jet geometry as described above. Furthermore, a method for preserving the jet of a liquid jet emerging from a flat jet nozzle is also described, wherein the liquid jet is enveloped by a gas curtain using such a nozzle attachment assembly.

[0033] In this way, the advantages and special features of the described nozzle attachment assembly are also realized within the framework of a system and a method for jet preservation.

[0034] Usefully, the described system can be designed for the flat jet nozzle to be integrally formed with the nozzle attachment assembly. For example, it is conceivable that the flat nozzle and the connecting element are firmly molded together, or that both elements are manufactured separately and then firmly connected. The term "firmly connected" can be understood, for example, as detachable, irreversibly detachable, or as firmly bonded. Bonded connections include, in particular, fusion, welding, soldering, and gluing.

[0035] Furthermore, it can be provided that a component of the flat jet nozzle forms a connecting element of the nozzle attachment assembly. In this way, the system can be designed to be particularly compact.

[0036] Here, too, further advantageous embodiments and further developments arise, each building on the further developments of the nozzle attachment assembly described above.

[0037] They show:

[0038] Figure 1 shows a simplified three-dimensional external representation of a first nozzle attachment assembly and a flat jet nozzle from a first viewing direction;

[0039] Figure 2 shows the nozzle attachment assembly shown in Figure 1 and the flat jet nozzle from a second viewing direction;

[0040] Figure 3 shows the nozzle attachment assembly shown in Figure 1 and the flat jet nozzle in a sectional view along a first plane;

[0041] Figure 4 shows the nozzle attachment assembly from Figure 1 and the flat jet nozzle in a sectional view along a second plane;

[0042] Figure 5 shows a simplified three-dimensional external representation of a second nozzle attachment assembly from a first viewing direction;

[0043] Figure 6 shows the second nozzle attachment assembly from Figure 5 from a second viewing direction; Figure 7 shows the second nozzle attachment assembly from Figure 5 in a sectional view along the first plane;

[0044] Figure 8 shows the second nozzle attachment assembly in a sectional view along the second plane;

[0045] Figure 9 shows a simplified three-dimensional external view of a third nozzle attachment assembly from a first viewing direction;

[0046] Figure 10 shows the third nozzle attachment assembly from Figure 9 from a second viewing direction;

[0047] Figure 11 shows the third nozzle attachment assembly in a sectional view along the first plane;

[0048] Figure 12 shows the third nozzle attachment assembly in a sectional view along the second plane;

[0049] Figure 13 shows a simplified three-dimensional external view of a fourth nozzle attachment assembly from a first viewing direction;

[0050] Figure 14 shows the fourth nozzle attachment assembly from Figure 13 from a second viewing direction;

[0051] Figure 15 shows the fourth nozzle attachment assembly in a sectional view along the first plane;

[0052] Figure 16 shows the fourth nozzle attachment assembly in a sectional view along the second plane;

[0053] Figure 17 shows a simplified three-dimensional external view of a fifth nozzle attachment assembly from a first viewing direction; Figure 18 shows the fifth nozzle attachment assembly from Figure 17 from a second viewing direction;

[0054] Figure 19 shows the fifth nozzle attachment assembly in a sectional view along the first plane;

[0055] Figure 20 shows the fifth nozzle attachment assembly in a sectional view along the second plane; and

[0056] Figure 21 is a flowchart of an exemplary method.

[0057] In the following description of the drawings, the same reference symbols refer to the same or comparable components.

[0058] Figure 1 shows a simplified three-dimensional external representation of a first nozzle attachment assembly 10 and a flat jet nozzle 20 from a first viewing direction. The illustrated nozzle attachment assembly 10 has an axial extension direction 24. A flat jet nozzle 20 is shown spaced apart from the nozzle attachment assembly 10 in the axial extension direction 24. The flat jet nozzle 20 itself comprises a flat jet nozzle outlet opening 64, through which liquid supplied to the flat jet nozzle 20 can exit in the form of a formed liquid jet.

[0059] The nozzle attachment assembly 10 comprises a connecting element 12 on a side facing the flat jet nozzle 20. On the side of the nozzle attachment assembly 10 facing away from the flat jet nozzle 20, a jet retention element 14 adjoins the connecting element 12. The jet retention element 14 is firmly connected to the connecting element 12 and can, for example, be formed integrally therewith, or one can be firmly formed onto the other.In Figure 1, several gas inlet openings 50 can be seen on the connecting element 12. Two further gas inlet openings 50 are arranged symmetrically to the two gas inlet openings 50 visible in Figure 1 in the areas not visible in Figure 1, i.e., the rear and underside of the connecting element 12. Thus, in total, four gas inlet openings 50 are provided circumferentially perpendicular to the axial extension direction 24 in the first nozzle attachment assembly 10 shown in Figure 1. These gas inlet openings 50 are arranged circumferentially, each rotated by 90° about the axial extension direction 24 as the axis of rotation. These gas inlet openings 50 are connected to gas channels (not shown in more detail) that extend into the interior of the nozzle attachment assembly. The jet retention element 14 comprises, on the side opposite the connecting element 12, an outlet side 26 with an outlet opening 28.

[0060] When the flat jet nozzle 20 is connected to the connecting element 12 of the nozzle attachment assembly 10 or is firmly but detachably connected thereto, a liquid jet formed by the flat jet nozzle 20 initially enters the nozzle attachment assembly 10 at the connecting element 12 in the axial extension direction 24, passes through the nozzle attachment assembly 10, and finally exits the jet retention element 14 of the nozzle attachment assembly 10 at the outlet opening 28. The internal geometry of the nozzle attachment assembly 10 is designed such that the formed liquid jet essentially does not touch an inner side of the nozzle attachment assembly 10 when correctly mounted on the flat jet nozzle 20, but rather forms a substantially constant gap with the inner side of the nozzle attachment assembly.The term "not touched" is to be understood as meaning that a surface of the liquid jet defined by the jet geometry is considered and does not "collide" with the nozzle attachment assembly. Individual liquid particles or droplets that may detach themselves from this surface of the liquid jet in a mist-like manner are not taken into account. Also shown in Figure 1 is a radial direction 46, which in cylindrical coordinates denotes a radial vector that is perpendicular to the axial extension direction 24 and locally rotated by an angle of rotation <p gedreht werden kann und dabei in jeder Winkelposition senkrecht zu der axialen Erstreckungsrichtung 24 steht. Figur 2 zeigt die erste Düsenvorsatzbaugruppe 10 gemäß Figur 1 aus einem anderen Blickwinkel, so dass in Figur 2 insbesondere eine Kopplungsstelle 18 an einer Stirnseite 16 der Düsenvorsatzbaugruppe 10 erkennbar ist.When the flat jet nozzle 20 is joined to the nozzle attachment assembly 10, the nozzle attachment assembly 10 is pushed onto the flat jet nozzle 20 opposite to the axial extension direction 24 in such a way that it clamps onto the surface of the flat jet nozzle 20. Furthermore, Figure 2 also shows a liquid supply line 62, via which the liquid required for jet formation, for example, water, is supplied to the flat jet nozzle 20.

[0061] Figures 3 and 4 each show the first nozzle attachment assembly 10 from Figure 1, wherein Figure 3 shows a sectional view of the nozzle attachment assembly and the flat jet nozzle 20 along a first plane, and in Figure 4, a second plane, which is perpendicular to the first plane, is selected as the sectional plane instead of the first plane. The choice of planes allows the interior of the nozzle attachment assembly 10 to be seen in Figures 3 and 4. In particular, an opening 52 can be seen in Figure 3 at the transition between the connection element 12 and the jet retention element 14. At the opening 52, a gas channel (not designated in more detail) opens into an expansion zone 30, which is formed inside the jet retention element 14.This expansion zone 30 is, as can be seen in Figure 4, bounded laterally by side walls 40, 42, with the two side walls 40, 42 diverging along the axial direction of extension 24, i.e., the further apart they become the further one moves in the axial direction of extension 24. This diverging of the side walls 40, 42 is advantageous but optional and can be omitted in this and all other embodiments, even if it is explicitly shown and described in the individual figures. On the two other opposite surfaces, the expansion zone 30 is bounded by cover sides 34, 36, so that the expansion zone 30 overall forms a fan-shaped structure, which has its "origin" at the transition between the beam retention element 14 and the connecting element 12.In Figure 4, two further opposing openings 54 can be seen in the transition area between the connecting element 12 and the jet containment element 14, which also connect gas inlet openings 50 to the expansion zone 30. During operation of the first nozzle attachment assembly 10, a fan-shaped liquid jet is formed inside the expansion zone 30 by the flat jet nozzle 20. As it flows past the openings 52, 54, the fan-shaped liquid jet draws in gas via the connecting channels 30 from the circumferentially arranged gas inlet openings 50, thereby forming a gas curtain that surrounds the liquid jet in the expansion zone 30 and later upon exiting the jet containment element 14, particularly in the form of a boundary layer that protects and stabilizes the liquid jet. The gas required for the formation of the uniform gas layer in the expansion zone 30 is thus provided via the gas inlet openings 50.

[0062] Figures 5 to 8 show simplified three-dimensional representations of a second nozzle attachment assembly 10. The respective viewing angles or sectional views selected correspond to the viewing angles or sectional views already known from Figures 1 to 4. A difference recognizable in Figure 5 between the second nozzle attachment assembly 10 and the first nozzle attachment assembly 10, which is shown analogously in Figure 1, is a stiffener 58 at the outlet-side end of the jet-preserving element 14. This stiffener 58 can advantageously counteract "pulsating flutter," such as is known, for example, from a loose end of a flexible hose from which liquid is sprayed, particularly in the case of a jet-preserving element made of an elastic material.Figure 6 shows that in the second nozzle attachment assembly 10 shown, the gas inlet openings 50 are arranged on the connection element 12, in particular on the end face 16 of the connection element 12. In this way, the gas inlet openings 50 are located in the immediate vicinity of the coupling point 18, so that, if necessary, the arrangement of the flat jet nozzle 20 at the coupling point 18 together with the connection of a gas supply line can be combined into a single common "connection step" or can be implemented using a common connecting element. Such a gas supply line is indicated in Figure 6, which can be designed, for example, as a simple gas-conducting hose, via which gas can be conveyed toward the gas inlet openings 50 if necessary.If such conveyance is not provided, when the nozzle attachment assembly 10 is operated with a flat jet nozzle arranged at the coupling point, the flat jet formed inside the jet retention element 14 again draws gas through the gas supply line 56 according to the principle of a water jet pump. This can be particularly advantageous for underwater applications, in which case the end of the gas supply line 56 facing away from the gas inlet opening 50 can then be kept floating on the water surface, for example.

[0063] Figures 7 and 8 now show the internal structure of the second nozzle attachment assembly 10 in the respective sectional views along the first plane and the second plane perpendicular to the first plane. Starting from the gas inlet openings 50, a branching gas channel structure 60 extends inside the nozzle attachment assembly 10, which connects a plurality of openings 52, 52', 52", 52"', 54 arranged at different positions to the gas inlet openings 50. In the transition region between the connection element 12 and the jet preservation element 14, the openings 52, 54 are again arranged on opposite sides, similar to the first nozzle attachment assembly 10 and also in Figures 1 to 4. In addition, however, further openings 52', 52", 52'" are arranged opposite one another on the cover sides 34, 36 of the expansion zone 30 along the axial extension direction 24.These openings 52', 52", 52'" further improve the compactness of the flat jet passing through the expansion zone 30 by continually sucking in additional gas as the formed flat jet passes the respective openings 52', 52", 52'" and adding it to the uniform gas layer around the flat jet. The sucked-in gas quantity transfers its momentum component directed towards the liquid jet to the latter, so that the liquid jet is newly / additionally focused in the exit direction, i.e., in the axial extension direction 24. The widths of the openings 52', 52", 52'" noticeably increase along the axial extension direction 24, since the flat jet, or rather the expansion zone 30 simulating it, widens along this extension direction 24. The laterally delimiting side walls 40, 42 diverge.The amount of gas sucked in through the individual openings 52, 52', 52", 52'", and 54 depends, among other things, on the length and cross-section of the gas channel(s) 60 connecting the openings 52, 52', 52", 52'", and 54 to the gas inlet openings 50. Accordingly, modeling or adjustment of the respective amount of gas sucked in is possible, which can be carried out, for example, experimentally or by means of a numerical simulation. Figure 7 also shows an unspecified optional web that serves to stiffen the nozzle attachment assembly. This unspecified web is also visible in Figure 8 near the opening 52" and appears to block the opening 52". In fact, however, only the selected cutting plane lies exactly within the web.

[0064] Figures 9 to 12 show simplified three-dimensional representations of a third nozzle attachment assembly 10. The third nozzle attachment assembly 10 shown in Figures 9 to 12 is, analogous to the first two nozzle attachment assemblies 10, shown in the associated Figures 1 to 4 and 5 to 8 respectively. The third nozzle attachment assembly 10 shown in Figures 9 to 12 is largely similar to the second nozzle attachment assembly 10 from Figures 5 to 8. In contrast to this, however, only two elongated, opposite gas inlet openings are shown on the front side 16, which, with the aid of suitable branches, enable gas to be sucked in at the openings 52, 52', 52", 52'" and 54, just as in the second nozzle attachment assembly 10.

[0065] Figures 13 to 16 show simplified three-dimensional representations of a fourth nozzle attachment assembly 10. Analogous to the various nozzle attachment assemblies 10 previously illustrated in Figures 1 to 12, a plurality of gas inlet openings 50 are distributed over the outer surface of the fourth nozzle attachment assembly 10 in the fourth nozzle attachment assembly 10. In particular, gas inlet openings 50 are also arranged on the jet containment element 14. As can be seen in Figures 15 and 16 in the respective sectional views of the fourth nozzle attachment assembly 10 along the first sectional plane and the second sectional plane, respectively, with the aid of the additional gas inlet openings 50, a direct connection between various openings 52, 52', 52", 52"', and 54 can be realized via non-branching gas channels 60.The resulting gas channels 60 are consequently very short, so that the quantity of gas that can be sucked in via the individual gas inlet openings 50 can be large.

[0066] Figures 17 to 20 show simplified three-dimensional representations of a fifth nozzle attachment assembly 10. Viewed from the outside, the fifth nozzle attachment assembly 10 is indistinguishable from the second nozzle attachment assembly 10 shown in Figures 5 to 8. However, upon closer study of Figures 19 and 20, which reveal the internal structure of the fifth nozzle attachment assembly 10, the projection 66 and the further projection 68 on the cover wall 34 become apparent. The two projections 66, 68 represent a structure of the cover wall 34 that reduces the otherwise constant distance h between the cover walls 34, 36. It can be assumed that projections 66, 68 are also arranged on the cover wall 36, which is not visible in Figure 19, in a manner symmetrical to the visible projections 66, 68.The projections 66, 68 reduce the gap width between the cover wall 34 and the passing liquid jet, thereby creating a pressure gradient in the uniform gas flow. This pressure gradient is based on the principle of the floor effect and has an attractive or repulsive effect on the passing liquid jet, so that, depending on the precise design of the projections 66, 68, its thickness can be homogenized across its width. Accordingly, after flowing past the projections 66, 68, the liquid jet can locally exhibit a slightly altered thickness across its width, reducing previously existing thickness differences.

[0067] The exact position and shape of the projections 66, 68 on the cover walls 34, 36 can be varied as needed and, in particular, can be determined / optimized experimentally for a specific flat jet nozzle. It is also possible, in particular, for more than two projections 66, 68 to be arranged simultaneously at different locations on the cover walls.

[0068] In the embodiment shown in Figure 19, the two projections 66, 68 are formed as triangles whose base surfaces are adjacent to one another and whose front tips (in the axial direction of extension) diverge, so that liquid is sucked "contactlessly" from a central middle region of the flat jet into the two opposite edge regions of the flat jet. Furthermore, modified opening side walls 70 of the openings 52, 52', 52", and 52"' are also visible (compared to Figure 8). These adjustments can cause slight changes in the pressure conditions in the uniform gas layer and accordingly contribute to the homogenization of the flat jet.

[0069] Figure 21 shows a flow diagram of an exemplary method 100. The method 100 can be used, in particular, to maintain the jet of a liquid jet formed by a flat jet nozzle. When carrying out the method 100, one of the nozzle attachment assemblies described above can be used. The method 100 typically begins with a suction 110 of gas via a gas inlet opening through a flowing liquid jet, which is a flat jet. This flat jet can, in particular, already be completely formed by a flat jet nozzle. The suctioned gas can then, in a subsequent step 120, a distribution and introduction, first be guided via gas channels to the openings present in the expansion zone of the nozzle attachment assembly, where it can be distributed and introduced into the expansion zone.This is followed by a further step 130, where a sliding layer is formed between the flat jet and the side walls, and the already formed flat jet flowing past is optimized. Optimization can be understood in particular as both compaction (for example, in the sense of bundling the liquid jet) and homogenization (for example, in the sense of equalizing the energy contained in the flat jet). After the flat jet has been optimized and thus preserved, a further step 140 ejects the optimized flat jet from the nozzle attachment assembly. This is also the point in time at which the flat jet exits the used nozzle attachment assembly again.Overall, it should be noted that the liquid jet flows continuously through the nozzle attachment assembly, and that the aforementioned chronological sequence of individual steps does not mean that the steps are performed one after the other. Rather, after an initial phase in which the liquid jet is established, the described steps are performed continuously and simultaneously, but can act on different areas of the liquid jet or be triggered by it, so that a chronological sequence should rather be understood with reference to a liquid element moving with the liquid jet.

[0070] The features of the invention disclosed in the above description, in the drawings and in the claims may be essential for the realization of the invention both individually and in any combination.

[0071] List of reference symbols

[0072] 10 Nozzle attachment assembly

[0073] 12 connecting element

[0074] 14 Beam preservation element

[0075] 16 Front side

[0076] 18 coupling point

[0077] 20 flat jet nozzle

[0078] 24 axial extension direction

[0079] 26 Exhaust side

[0080] 28 Outlet opening

[0081] 30 Expansion Zone

[0082] 34 Ceiling wall

[0083] 36 Ceiling wall

[0084] 40 side wall

[0085] 42 side wall

[0086] 46 radial direction

[0087] 50 Gas inlet opening

[0088] 52 Opening

[0089] 52' opening

[0090] 52" opening

[0091] 52" opening

[0092] 54 Opening

[0093] 56 Gas supply line

[0094] 58 stiffening

[0095] 60 gas duct

[0096] 62 Liquid supply line

[0097] 64 Flat jet nozzle outlet opening

[0098] 66 lead

[0099] 68 further lead

[0100] 70 Opening side wall procedure

[0101] Suction

[0102] Distribute and introduce

[0103] Training and optimization

[0104] emissions

Claims

Claims 1. Nozzle attachment assembly (10) comprising a connecting element (12) with a coupling point (18) arranged on an end face (16) for receiving a flat jet nozzle (20) of a liquid-operated high-pressure cleaner, wherein a jet retention element (14) adjoins the connecting element (12) along an axial extension direction (24) of the nozzle attachment assembly (10), wherein the jet retention element (14) comprises an outlet opening (28) on an outlet side (26) facing away from the end face (16), which outlet opening is in fluid-conducting connection through the interior of the nozzle attachment assembly (10) with the coupling point (18), wherein the fluid-conducting connection is designed as an expansion zone (30) which is delimited in a first plane perpendicular to the axial extension direction (24) by cover walls (34, 36) which have a distance h and which are arranged in a second plane, which is perpendicular to the first plane, is bounded by side walls (40, 42),so that the expansion zone (30) as a whole replicates a jet geometry of the accommodateable flat jet nozzle (20) in such a way that a liquid jet formed with this jet geometry is continuously surrounded by a circumferential gap within the expansion zone (30) in a radial direction (46) perpendicular to the axial extension direction (24), and, wherein the connecting element (12) and / or the jet retention element (14) has at least one gas inlet opening (50) which opens into the expansion zone (30).

2. Nozzle attachment assembly (10) according to claim 1, wherein the at least one gas inlet opening (50) is closable or adjustable.

3. Nozzle attachment assembly (10) according to claim 1 or 2, wherein the at least one gas inlet opening (50) opens into the expansion zone (30) at at least two mutually separate openings (52, 54), wherein at least one opening (52) is provided on each cover wall (34, 36).

4. Nozzle attachment assembly (10) according to one of the preceding claims, wherein the at least one gas inlet opening (50) opens into the expansion zone (30) at at least four mutually separate openings (52, 54), and wherein at least one opening (52) is provided on each top wall (34, 36) and furthermore at least one opening (54) is also provided on each side wall (40, 42).

5. Nozzle attachment assembly (10) according to one of the preceding claims, wherein the side walls (40, 42) diverge in the axial extension direction (24) so ​​that the expansion zone (30) widens in a fan shape.

6. Nozzle attachment assembly (10) according to one of the preceding claims, wherein openings (52; 54) provided on the opposing cover and / or side walls (34, 36; 40, 42) are arranged symmetrically to one another in pairs.

7. Nozzle attachment assembly (10) according to one of the preceding claims, wherein on each of the opposing cover walls (34, 36) in the axial extension direction (24) a plurality of openings (52, 52', 52") are provided, the respective width of which increases with increasing distance from the connecting element (12).

8. Nozzle attachment assembly (10) according to one of the preceding claims, wherein at least one structuring projection is provided on each of the opposing cover walls (34, 36), which locally reduces the distance h between the cover walls (34, 36).

9. Nozzle attachment assembly (10) according to one of the preceding claims, wherein gas inlet openings (50) are provided on the end face (16).

10. Nozzle attachment assembly (10) according to one of the preceding claims, wherein the jet preservation element (14) can be assembled modularly from a plurality of individual elements, and wherein the plurality of individual elements can be connected to one another in the axial extension direction.

11. System comprising a flat jet nozzle (20) which is designed to form supplied liquid into a flat jet with a jet geometry, and a nozzle attachment assembly (10) adapted to this jet geometry according to one of claims 1 to 10.

12. System according to claim 11, wherein the flat jet nozzle (20) is formed integrally with the nozzle attachment assembly.

13. System according to claim 11 or 12, wherein a component of the flat jet nozzle forms a connecting element (12) of the nozzle attachment assembly (10).

14. Method 100 for preserving the jet of a liquid jet emerging from a flat jet nozzle (20), wherein the liquid jet is enveloped by a gas curtain using a nozzle attachment assembly (10) according to one of claims 1 to 10.

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