Pollutant-free aerosol generator with simplified design

Abstract

The present invention relates to an aerosol generator comprising a nozzle disk (2) with a central region (21) having a plurality of continuous nozzle openings (210), and an annular vibration generator (13) with a circular concentric opening (30), which is mechanically coupled to an edge region (22) of the nozzle disk (2) in order to set the latter into transverse vibrations, wherein the nozzle disk (2) covers the annular opening (30) of the vibration generator (3), wherein the vibration generator (13) consists exclusively of a piezoceramic ring (3), to which the nozzle disk (2) is integrally connected by means of a cured adhesive (4) to an adhesive region of an underside (32) of the piezoceramic ring (3). The invention also relates to a manufacturing method for such an aerosol generator.

Description

[0001] The present invention relates to an aerosol generator according to the preamble of claim 1 and a manufacturing method for such an aerosol generator. State of the art

[0002] Devices for nebulising liquids are known, i.e. devices that convert a continuous volume of liquid into an aerosol of fine liquid droplets, which is dispensed at a dispensing opening. A frequently used type of nebuliser for this purpose contains aerosol generators comprising a usually circular nozzle disc that is mechanically coupled to a vibration generator. The nozzle disc, which is often also referred to as a mesh membrane, typically has a plurality of continuous nozzle openings in a central, dome-shaped area, whereby these nozzle openings taper in particular from an inlet side to the outlet side. This nozzle disc is circumferentially connected to the vibration generator in a materially or force-fitting manner with the circular and thus flange-like edge area adjoining the dome-shaped central area.Through this mechanical coupling, vibrations of the vibration generator are transmitted to the nozzle disc and cause it, or its central area with the nozzle openings, to undergo transverse bending vibrations, i.e. bending vibrations directed along its rotational symmetry axis.

[0003] The vibration generator is usually also rotationally symmetrical about the axis of rotational symmetry shared with the nozzle disk, in particular essentially circular and with a concentric opening concealed by the nozzle disk. It is typically constructed from a piezoceramic ring and a carrier disk. The piezoceramic ring represents the actual vibration-generating element and is subjected to an alternating voltage for this purpose. The carrier disk provides the mechanical stability lacking in the piezoceramic ring, but does not itself contribute to generating the vibrations. Nevertheless, its mass and elastic modulus strongly influence both the frequency and amplitude of the vibrations generated by the piezoceramic ring and transmitted to the nozzle disk.

[0004] A device of the type described above is shown, for example, in the international publication WO 93 / 109100. More specifically, it recommends a material-to-material bond between the vibration generator and the nozzle disc using an adhesive. This document thus serves as an example for a multitude of other publications that disclose aerosol generators with the above-described design.

[0005] Patent EP 2 569 033 B1 discloses an aerosol generator assembly which, like the one described above, comprises a circular ring-shaped piezoceramic body. However, this body is coated with an electrical contact material in an outer region and has a contact material-free inner region which is in direct contact with the flange-shaped edge or contact area of ​​the nozzle disc. This document does not teach a permanent attachment of the nozzle disc to the piezoceramic body; rather, the mechanical coupling between the piezoceramic rings and the nozzle disc, necessary for effective vibration transmission, is achieved by pressing the two against each other by means of a clamping device, namely the nebulizer housing housing the aerosol generator.

[0006] European Patent Application EP 1 762 264 A1 describes an ultrasonic nebulizer that also includes a nozzle disk mechanically coupled to a circular piezoelectric ceramic element. The nozzle disk, together with the piezoelectric element, is firmly glued into the outlet opening of the nebulizer housing. The aerosol generator is therefore not a separate, removable component. Replacement, for example, during a nebulizer repair, is therefore not possible without causing damage.

[0007] Patent EP 3 103 497 B1 discloses a nebulizer that also features a circular piezoceramic element in direct contact with the edge area of ​​a nozzle disc. Here, too, the piezoceramic element and nozzle disc are not bonded together, but rather are only connected by force, or more precisely, by clamping.

[0008] The published international patent application WO 2021 / 033128 A1 discloses various embodiments of aerosol generators with and without carrier discs. The latter, in particular, are described in the Fig. 4a to 4d are shown and are described on page 24 from line 30 to page 25, line 6. There, it is also taught that the nozzle disc and the piezoceramic ring are not permanently connected to each other, but rather that they are kept in contact with each other simply by mechanical tension when installed together in the nebulizer.

[0009] The detachable mechanical contact between the nozzle disc and the piezoceramic ring offers the advantage that each part is individually replaceable. A disadvantage, however, is that the transmission of mechanical vibrations is highly dependent on clean, full-surface contact and the mechanical clamping force with which both elements sit in their holders in the nebulizer housing. If this force is insufficient, or if it has decreased over the course of the nebulizer's use due to aging of the bearing rubber rings, efficient transmission of the vibrations generated by the piezoceramic ring to the nozzle disc is no longer guaranteed. Accordingly, the vibration amplitude and thus the amount of aerosol delivered are reduced. The same applies in the case of asymmetrical clamping, although this still carries the risk of damage to the aerosol generator, particularly the piezoceramic ring.

[0010] In addition, installing the aerosol generator as separate parts requires greater effort and greater precision in positioning the components relative to each other and in their mounting within the nebulizer housing. This precision is necessary, firstly, to avoid the aforementioned asymmetric clamping. Secondly, it also ensures that the aerosol generator prevents the fluid bearing on it in the nebulizer's medication housing from flowing laterally around it or through gaps between the components, which are merely mechanically pressed together.

[0011] This is particularly critical given that regulations regarding the contamination of nebulized medications with toxic substances by or in nebulizer devices are becoming increasingly strict. Some nebulized medications contain chemically corrosive components, which can leach substances from nebulizer components. If these substances are harmful to health, the beneficial therapeutic effect of using the nebulizer is jeopardized. General description of the invention

[0012] Against this background, the present invention aims to develop an aerosol generator for a nebulizer that combines a comparatively simple design with high mechanical efficiency and ease of handling, even when installed in the nebulizer. A further objective of the invention is to ensure that the aerosol generator emits as little pollutant as possible.

[0013] This is achieved by a nebulizer according to claim 1 which can be manufactured according to the method of claim 15.

[0014] The essential improvements of the aerosol generator according to the invention are that the vibration generator consists solely of the piezoceramic ring, to which the nozzle disk is directly bonded, in particular glued. A carrier disk located between the nozzle disk and the piezoceramic ring, which mechanically supports the latter, is omitted. This increases mechanical efficiency, and significantly simplifies the design of the aerosol generator according to the invention and thus its manufacture. First, by eliminating the carrier disk, one less part needs to be manufactured or provided.Furthermore, one less adhesive connection has to be realized, i.e. it is no longer necessary to first glue the piezoceramic ring onto the carrier disc and then connect it to the nozzle disc, but only a single connecting process takes place, which according to the invention consists in gluing the nozzle disc directly onto the piezoceramic ring.

[0015] To achieve this, the piezoceramic ring must be sufficiently stable, i.e. it must be designed to be sufficiently robust to withstand the loads exerted on it during operation and, above all, during manufacturing, even without the mechanical support of the carrier disk. The loads that occur during intended use and correct installation of the aerosol generator in the nebulizer are not the limiting factor, as they act more or less symmetrically on the aerosol generator, or in particular, its piezoceramic ring. Asymmetrical or localized loads during manufacture of the aerosol generator or during its installation in the nebulizer can be particularly dangerous. This can occur, for example, if the aerosol generator is gripped roughly and / or unevenly before installation and / or is subjected to bending forces during installation in the nebulizer housing.

[0016] In order to give the aerosol generator of the present invention sufficient stability to withstand the unavoidable and, at least to a certain extent, hardly avoidable asymmetrical loads during production, it is proposed in the preferred embodiment to make the piezoceramic ring thicker than has previously been the case. Piezoceramic rings previously used in conjunction with a supporting carrier disk typically had a thickness / strength of between 0.1 mm and 0.3 mm, frequently about 0.2 mm. Within the scope of the present invention, piezoceramic rings to be connected directly to the nozzle disk preferably have thicknesses of more than 0.3 mm, in particular 0.4 mm to about 1.0 mm, preferably between 0.4 and 0.6 mm, particularly preferably about 0.5 mm.

[0017] Not all nozzle disc materials are amenable to direct bonding. For example, nickel nozzle discs are frequently used in nebulizers because they can be manufactured electrogalvanically, which is comparatively inexpensive, quick, and with the necessary precision. Precision is particularly important with regard to the nozzle openings, which preferably have a funnel shape tapering towards the outlet side, with the outlet opening having a diameter of only a few micrometers, as this corresponds to the desired aerosol droplet size. The problem with nickel nozzle discs is that no biocompatible adhesives are known with which a sufficiently durable, material-locking connection between the nozzle disc and the carrier disc (according to the prior art) or piezoceramic (according to the present invention) could be created.

[0018] In order to be able to attach such discs, the applicant has developed a so-called sandwich construction or sandwich technology, in which the nozzle disc is embedded between the vibration generator on one side and a circular counter disc, or counter ring, on the other. The counter disc and vibration generator are connected to one another via columns of cured adhesive that penetrate the bonding openings located in the edge area of ​​the nozzle disc. Such a fastening is not only sufficiently stable, but also offers the advantage that the mechanical forces are essentially transmitted from the vibration generator to the nozzle disc only via the adhesive columns and the inner surfaces of the bonding openings. According to the applicant's experience, this leads to particularly efficient and fine-droplet atomization.

[0019] The present invention now envisages use with both nozzle discs with bonding openings and nozzle discs without bonding openings. In the former case, the aerosol generator has a structure comprising at least three components: a piezoceramic ring, directly with the nozzle disc bonded to it, and, at the top, the counter ring that covers the bonding openings. An even simpler structure is possible when using a nozzle disc without bonding openings, because in this case, the aerosol generator comprises only the piezoceramic ring with the nozzle disc bonded to its underside.

[0020] The aerosol generator can further comprise, in a known manner, an insulating disc, which is placed or preferably also glued to the upper side opposite the underside connected to the nozzle disc. The insulating disc forms a barrier that primarily protects the piezoceramic ring from contact with the liquid to be nebulized. This prevents corrosion of the piezoceramic from potentially corrosive liquids to be nebulized, such as non-pH-neutral (i.e., acidic or basic) medication liquids, or even those containing salts.Since the aerosol generator according to the invention is usually installed in a nebulizer in such a way that the underside of the piezoceramic ring with the nozzle disc faces the chamber containing the liquid to be nebulized and the upper side faces away from it, the insulating disc located on the upper side of the piezoceramic ring essentially protects against contact with precipitating aerosol.

[0021] The method for producing an aerosol generator according to the invention comprises the steps of providing the nozzle discs and a piezoceramic ring, applying the adhesive layer to the adhesive section of the adhesive area of ​​the piezoceramic ring, i.e. the section which is to be in contact with the nozzle disc via the adhesive layer in the finished aerosol generator, and placing and pressing the adhesive disc in place with subsequent curing of the adhesive.

[0022] Within the scope of the invention, various adhesives, and especially different types of adhesive, can be used. Depending on the type of adhesive, the fourth curing step varies.

[0023] Conventional aerosol generators typically use thermally curing adhesives. During thermal curing, the aerosol generator must be heated to a specific (high) temperature in an oven, such as an autoclave, for a specific period of time. The piezoceramic ring can be bonded to the carrier disk on one side and the nozzle disk to the carrier disk on the other side using the same or two different thermally curing adhesives. Such thermally curing adhesives can be one-component epoxy resins with curing temperatures of 80–150°C and curing times of a few minutes to an hour or several hours, for example, approximately 2 hours, or two-component epoxy resin-based adhesives, which require curing temperatures of 100–150°C and curing times of only a few to a few tens of minutes, for example, approximately 10–15 minutes.

[0024] Thermally curing adhesives are also conceivable in principle for an aerosol generator according to the invention, but they have the disadvantages of high energy consumption, the need to purchase and maintain ovens, and increased production time, which is why other solutions are generally preferred. This is all the more true since the necessary high-temperature curing phase limits the selection of piezoceramic materials. Conversely, for a given or desired piezo material, the maximum possible curing temperature is limited by the piezoelectric Curie temperature of the material, above which a rearrangement of the crystal structure occurs, with a concomitant reduction or loss of piezoelectric properties. For safety reasons, manufacturers of piezoelectric materials typically specify a maximum permissible temperature of half the Curie temperature.

[0025] Because the present invention reduces the number of required bonding processes from the previous two (first piezoceramic to carrier disk, then nozzle disk to carrier disk) to one (nozzle disk directly to piezoceramic, possibly adding a counter disk on the back of the nozzle disk edge area in the same step), at least the time disadvantage compared to previous aerosol generators is significantly reduced, even when using a thermal adhesive. However, the effort and costs associated with the continued need for high-temperature furnaces, as well as the thermal stress on the piezoceramic ring, remain.

[0026] Alternatively, the bond between the piezoceramic ring and the nozzle disk, and possibly the backing disk, can be created using a solvent-based adhesive. After application, this adhesive is allowed to dry passively at room temperature or at slightly elevated temperatures, thus curing. High-temperature furnaces are unnecessary. However, the drying or curing time is longer than with a thermally cured adhesive, which adversely affects production time.

[0027] Against this background, a hybrid adhesive is preferably used within the scope of the present invention, one that is curable both by the evaporation of a solvent and by means of light, specifically UV light. Examples include acrylate-based adhesives that contain a photoinitiator. The latter are chemical compounds that, after absorbing UV light (usually UV light in technical applications), decompose into reactive fragments in a photolysis reaction. These fragments can then initiate reactions, such as a polymerization reaction in the case of optically curing or the hybrid adhesive of interest here. All adhesives used to manufacture a nebulizer or aerosol generator for use by patients must be fully biocompatible according to ISO 10993. This presents an additional challenge, but such hybrid adhesives are known.

[0028] When using such an adhesive, curing can comprise at least two temporal phases. In an active phase, at least part of the adhesive layer is actively cured by exposure to light of a suitable spectral composition, such as UV light or light with a high UV content. In a passive phase, curing takes place passively, as the solvent gradually evaporates and the remaining adhesive molecules gradually solidify. The active phase is typically significantly shorter than the passive phase, for example, between a few tens of seconds and one to several minutes, and can occur before, during, or after the passive phase.It is particularly preferred to start curing with the active phase so that the connection between the piezoceramic ring and the nozzle disc already has a certain basic strength before the final strength is reached in the subsequent passive phase, which typically lasts from a few tens of minutes to one or a few hours at room temperature.

[0029] The crosslinking of the hybrid adhesive, which provides the basic strength, takes place in the edge regions of the adhesive layer accessible to light rays, whereas the inner sections of the adhesive layer located between the piezoceramic ring and the nozzle disk cannot be exposed to light, as neither the piezoceramic ring nor the nozzle disk are transparent to light, including UV or infrared light. For this reason, the use of a purely light-curing adhesive instead of a hybrid adhesive is ruled out. The edge regions of the adhesive layer accessible to light are a radially inner, annular first region, which is adjacent to the concentric through-opening of the piezoceramic ring or the central region of the nozzle disk. Furthermore, a radially outer, second region can also be exposed to light.

[0030] The basic bond strength achievable by light curing can be advantageously increased if the amount of (hybrid) adhesive used during production is such that it is sufficient to form an annular bead or wall that protrudes beyond the outer edge of the nozzle disc (which is smaller than the piezoceramic ring) and touches the cylindrical outer surface of the nozzle disc. When using an adhesive of suitable viscosity, this bead or wall usually has sufficiently extensive and uniform contact with the cylindrical outer surface of the nozzle disc simply after it has been pressed against it. If this is not the case to the desired extent, or simply to ensure this in every case, the annular adhesive wall / ring wall can be pressed circumferentially against the cylindrical outer surface of the nozzle disc in an intermediate step after pressing but before light curing and, in particular, also further shaped, for example, smoothed.In preferred embodiments, the outer surface of the annular wall, resulting from the simple pressing or actively smoothing, facing away from the outer surface of the nozzle disk, preferably forms an acute angle with the underside of the piezoceramic ring. Alternatively or simultaneously, it can also form an acute angle with the cylindrical outer surface of the nozzle disk.

[0031] Since it is geometrically not covered by an opaque component, the annular wall achieves its final strength simply through light curing. Such an annular adhesive wall can be used in aerosol generator designs that utilize a nozzle disc without bonding openings, as well as in designs with a nozzle disc with bonding openings that is bonded in a sandwich construction between the piezoceramic ring and the counter disc. In the latter case, the annular wall preferably extends axially to the counter disc or, in particularly preferred designs, can also partially or completely cover the cylindrical outer surface of the counter disc.

[0032] Regardless of the type of adhesive, i.e., its curing, it is preferable to use an adhesive that initially has an average viscosity in the range of approximately 500 mPa s to 3000 mPa s, in particular between 600 and 1500 mPa s. It has been shown that this viscosity provides sufficient flowability to form a uniform adhesive layer when the components are pressed together, while at the same time maintaining a defined shape and preventing uncontrolled flow.

[0033] As already described above, the piezoceramic ring is preferably protected from contact with the liquid to be nebulized by an insulating disk on its top. However, the insulating disk, which is usually located on the outlet side of the piezoceramic ring, cannot prevent such contact in all cases. In particular, the inner surfaces of the concentric through-hole of the piezoceramic ring can come into contact with precipitating aerosol and may therefore be exposed to a corrosive effect of the liquid, which can dissolve substances from the piezoceramic ring. To prevent harmful substances from entering the inhaled aerosol, further preferred embodiments of the aerosol generator according to the invention use a piezoceramic ring made of a lead-free piezo material. Examples of suitable materials include: berlinite (ALPO4), langasite (La3Ga5SiO 14), gallium (ortho)phosphate (GaPO4), lithium niobate (LiNbO3), lithium tantalate (LiTaO3), aluminum nitrite (AIN), zinc oxide (ZnO), sodium / potassium niobate ((Na,K)NbO3), barium titanate (BaTiO3), bismuth ferrite (BiFeO3), sodium bismuth titanate (NaBi(TiO3)2), sodium tungstate (Na2WO3) or polyvinyl fluoride (PVDF).

[0034] Even more preferably, the piezo material contains no harmful heavy metals at all, i.e., apart from lead, no barium, bismuth or tungsten.

[0035] Due to its intended use, the nozzle disc cannot be protected from contact with liquid. Coating it with a material that forms a protective barrier is technically difficult to implement due to the mechanical deformation associated with vibrations, but above all due to the fine nozzle openings, which would naturally have to remain or be made transparent even after coating, for example with gold or another precious metal. However, this solution is primarily of little interest from an economic perspective, as the production of such a coated nozzle disc would be too complex. Therefore, it is still preferred if the nozzle disc is made of a material that is hardly or not at all corrodible, such as a stainless steel alloy, especially one that contains as little nickel as possible.

[0036] The aerosol generator according to the invention represents a significant improvement over the prior art, as its manufacture is significantly simpler and yet still provides a mechanically efficient transmission of vibrations from the vibration generator, which according to the invention consists solely of the piezo ring itself, to the nozzle disk to be vibrated. Furthermore, the costs of manufacturing or providing a carrier disk are saved. To compensate, the piezoceramic ring is provided in a slightly to significantly increased thickness, which increases the pure material costs for the piezoceramic material. However, the manufacturing or provision costs of the piezoceramic ring are dominated by machining, and the required machining precision and thus complexity are higher for thin piezo rings than for thicker ones.For this reason, the costs for providing the piezoceramic ring are also reduced, so that the invention achieves a double saving in provision costs.

[0037] Further advantageous developments, which can be implemented individually or in combination, provided they do not obviously exclude each other, are claimed in the subclaims and will be described individually below.

[0038] As usual, the nozzle disc preferably has a dome-shaped, curved central area in which the nozzle openings are arranged. The nozzle disc is preferably connected to the piezoceramic ring in such a way that the curvature of the central area points toward the interior of the ring or protrudes into it. Because the aerosol generator is installed in the nebulizer in such a way that the nozzle disc is on the side of the liquid to be nebulized and the piezoceramic ring is on the aerosol outlet side, the curved central area of ​​the nozzle disc points toward this outlet side.

[0039] In preferred embodiments, the piezoceramic ring has a thickness of between 0.3 mm and 1.0 mm, in particular 0.4 mm to 0.6 mm, particularly preferably 0.5 mm, a clear inner diameter of 4 mm to 28 mm, in particular about 8 mm and an outer diameter of between 6 mm and 35 mm, in particular about 21 mm.

[0040] In further preferred embodiments, the nozzle disc has an (outer) diameter of between 5 mm and 30 mm, in particular approximately 12 mm, and a dome-shaped central region which measures between 3 mm and 15 mm, in particular approximately 8 mm, wherein the partial region occupied by the nozzle openings, which is usually arranged concentrically, measures between 3 mm and 12 mm, in particular approximately 5 mm.

[0041] In embodiments of the aerosol generator according to the invention with an insulating disk, the insulating disk is preferably integrally connected to the piezoceramic ring, in particular glued. A transparent insulating disk is preferably used in conjunction with a light-curing adhesive. Alternatively, to further simplify the manufacturing process, the same adhesive can be used that also serves to integrally connect the nozzle disk and the piezoceramic ring. The insulating disk is preferably made of plastic. It also preferably has a thickness of between 0.01 mm and 0.2 mm, in particular between 0.05 mm and 0.1 mm, and particularly preferably approximately 0.05 mm. Detailed description of the implementation examples

[0042] Further advantages, properties, and features of the present invention will become apparent from the exemplary embodiments presented below with reference to the figures. These are intended merely to illustrate the invention and not to limit its generality.

[0043] Showing: Fig. 1A: A perspective disassembled view of a known aerosol generator comprising a vibration generator consisting of a carrier disk and a thin piezoceramic ring. Fig. 1B: A section through the well-known aerosol generator of the Fig. 1A. Fig. 2A: A perspective disassembled view of an aerosol generator according to a first preferred embodiment of the invention comprising a vibration generator in the form of a piezoceramic ring of greater thickness with a nozzle disc with adhesive openings attached thereto using a sandwich technique. Fig. 2B: A section through the aerosol generator of the Fig. 2A. Fig. 3A: A perspective disassembled view of an aerosol generator according to a second preferred embodiment of the invention comprising a vibration generator in the form of a piezoceramic ring of greater thickness with a nozzle disk firmly attached thereto without adhesive openings. Fig. 3B: A section through the aerosol generator of the Fig. 3A.

[0044] In the Fig. 1A and Fig. 1B shows an aerosol generator as known from the prior art.

[0045] The known aerosol generator 1' consists of the vibration generator 13, the nozzle disk 2 arranged below along the rotational symmetry axis S oriented in the aerosol discharge direction, the counter disk 5 arranged on the side of the nozzle disk 2 facing away from the vibration generator, and the annular insulating film 6 arranged on the top side of the vibration generator. The vibration generator 13, in turn, consists of the carrier disk 12 and the actual vibration-generating piezoceramic ring 3'. The latter's comparatively small thickness, combined with the fact that the piezo material is comparatively brittle and fragile, means that the piezoceramic ring 3' is dependent on the carrier disk 12 in order to withstand the stresses, particularly those associated with installation in a nebulizer, without damage.

[0046] The nozzle disc 2 comprises a circular edge region 22 and a dome-shaped central region 21 curved in the aerosol discharge direction. The central region 21 comprises a plurality of nozzle openings 210, arranged in particular in a grid-like manner, which are typically funnel-shaped as shown. In the scale drawing Fig. 1A the nozzle openings are not resolved due to their small size, in the more schematic Fig. In Figure 1B, they are shown significantly enlarged for clarity. The nozzle disc 2 is firmly bonded to an adhesive area of ​​the vibration generator, more precisely, the carrier disc 12, by means of the edge region 22.

[0047] The Fig. 1A individually shown components of the aerosol generator 1 are as in Fig. 1B, they are bonded together by adhesive layers 4o, 4t. The adhesive layers 4o, 4t are shown in exaggerated thickness in the figure for better visibility.

[0048] In the known aerosol generator, a thermally curing adhesive is used to connect the piezoceramic ring 3' to the carrier disk 12 to form the vibration generator 13 as well as to connect the vibration generator 13 to the nozzle disk 2, which has the disadvantages of high energy consumption, high stress on the comparatively temperature-sensitive piezo ring 3' and higher manufacturing costs due to the fact that corresponding high-temperature furnaces are required.

[0049] Particularly when the nozzle disc 2 is made of or coated with a material that is difficult to bond, such as nickel or fluorine-terminated plastics, only an indirect, material-to-material fastening in a sandwich construction is possible. This is achieved, as shown in the figures, by the nozzle disc 2 having circumferentially distributed bonding openings 220 in its edge region 22. When the nozzle disc 2 is pressed with its front side 221 onto the bonding area 321 of the carrier disc 12, which is provided with an adhesive bead, the still-liquid adhesive swells and reaches the rear side 222 of the edge region 22, facing away from the vibration generator.There, the counter disc 5 is then placed on the oozed adhesive and pressed firmly into place such that a uniformly thick, circular lower adhesive layer 4t2 is formed, which is firmly bonded to the counter disc 5, but not, or only to a lesser extent, to the opposite rear side of the nozzle disc edge region 22. Likewise, the upper adhesive layer 4t1, located above in the aerosol dispensing direction, forms a durable bond only with the adhesive region 321 of the carrier disc. The nozzle disc 2 is thus essentially held in place by the multitude of adhesive columns penetrating the bonding openings 220 and connecting the upper adhesive layer 4t1 to the lower adhesive layer 4t2. The introduction of radial (vibration) forces into the nozzle disc 2 thus occurs via the interaction of these adhesive columns with the inner surfaces of the bonding openings 220.

[0050] The piezoceramic ring 3' is covered by a transparent insulating disc 6, which is glued to the top of the vibration generator 13. Due to the transparency of the insulating disc 6, it is possible to bond it to the vibration generator using a light-curing adhesive 4o that cures quickly and relatively easily.

[0051] The Fig. 2A and Fig. 2B show a first preferred embodiment of an aerosol generator according to the invention comprising a nozzle disc with bonding openings and an oscillation generator consisting exclusively of a piezoceramic ring of sufficient thickness.

[0052] In this embodiment, the aerosol generator 1 also consists of a vibration generator 13 with a nozzle disc 2 attached to it by means of a sandwich construction. In contrast to the known aerosol generator of the Fig. 1, however, it consists only of the piezoceramic ring 3. To ensure that it is sufficiently robust for the stresses encountered during operation and, above all, during the manufacture of the aerosol generator 1 and its installation in a nebulizer, it is significantly thicker than the piezoceramic ring 3' of the known aerosol generator 1'. In preferred embodiments, the piezoceramic ring can, for example, have a thickness of approximately 2.5 times greater, at approximately 0.5 mm, compared to the approximately 0.2 mm of the known piezoceramic ring 3'.

[0053] By omitting the carrier disc, the structure and thus the manufacture of the aerosol generator 1 is significantly simplified. In comparison to the two successive bonding steps in the manufacture of the known aerosol generator 1' of Fig. 1 (bonding the piezoceramic ring 3' to the carrier disk 12 including curing, followed by bonding the nozzle disk 2 to the carrier disk 12), only a single bonding step is required, because the nozzle disk 2 is directly bonded to the piezoceramic ring 3. Due to this halving of the bonding steps, a significant time and cost advantage can be achieved in production, even when using a thermally active, curing adhesive. However, this is further advantageously improved if a hybrid adhesive is used instead of a thermally curing adhesive, which cures actively by exposure to light of a suitable spectral composition but also passively by slowly curing as a solvent evaporates.

[0054] During production, in the sandwich construction known from the previously described method, this adhesive is applied in a thin layer or as an adhesive bead to the adhesive area 321 of the underside 32 of the piezoceramic ring 3. The nozzle disc 2 is then placed on the front side 221 of its edge area 22 and pressed firmly in place such that the adhesive swells through the bonding openings 220. The counter disc 5 is placed on the rear side 222 and also pressed firmly in place. The adhesive layers above and below the edge area 22 should be as uniformly thick and homogeneous as possible, both radially and circumferentially, and in particular free of bubbles. The amount of adhesive can be measured, as in the known aerosol generator, such that it is sufficient only for the formation of these layers and the adhesive columns penetrating the bonding openings.In addition, however, further adhesive can also be provided to form an adhesive ring wall 41 contacting the nozzle disc 2 on its cylindrical peripheral surface 29.

[0055] To cure, the hybrid adhesive is first exposed to light of a suitable spectral composition during an active curing phase. This light cannot reach all areas of the adhesive layer 4. When irradiated along the axis of symmetry S, the non-transparent components 5 and 3 block the light. Irradiation perpendicular to S is only possible for the lower adhesive layer, both from the radial inside and outside. The upper adhesive layer located between the nozzle disk edge 22 and the piezoceramic ring 3 can only be irradiated from the radial outside due to the dome-shaped central region 21 of the nozzle disk 2. In any case, however, the radially irradiated light can only penetrate a comparatively short distance into the adhesive layer due to the strong absorption in the adhesive.The light-curing effect is also limited by the small lateral entry area of ​​only one to a few tenths of a millimeter – the typical thickness of the adhesive layer – which would require high irradiances to achieve sufficient radiation energy deposited inside. The further inner areas of the adhesive layer are therefore not reliably light-curable.

[0056] However, during the manufacturing of the aerosol generator, it is sufficient if only the outer areas are cured during the first, active curing phase. This already achieves a certain basic strength of the bond between the nozzle disc 2 and the piezoceramic ring 3. The final strength is achieved in the subsequent passive curing phase, during which the solvent of the hybrid adhesive gradually evaporates from the non-light-curable inner areas of the adhesive layer 4, causing the adhesive to cure there as well.

[0057] The adhesive ring wall 41 is very helpful for basic strength. Due to its material connection with the cylindrical outer surface 29 of the nozzle disc 2, it holds it from the outside and is completely light-curable due to its exposed, unshaded position.

[0058] The insulating disc 6 corresponds in its material and the type of material-locking fastening on the vibration generator 13 or here piezoceramic ring 3 to the insulating disc of the known aerosol generator of the Fig. 1.

[0059] In the Fig. 3A and Fig. 3B shows an aerosol generator according to the invention according to a second preferred embodiment, which, like the first embodiment, comprises a vibration generator which consists exclusively of a piezoceramic ring of greater thickness, but enables even simpler and faster production by using a nozzle disc without bonding openings.

[0060] In this embodiment, the aerosol generator 1 comprises only two main components: the vibration generator 13 in the form of the piezoceramic ring 3 and the nozzle disc 2. The latter has no adhesive openings 220 in its outer region 22 but is only connected with its front side 221 to the adhesive area 321 of the piezoceramic ring 3 by means of the adhesive layer 4.

[0061] Here, too, a hybrid adhesive that is actively curable by light and passively curable by solvent evaporation of the type described above is preferably used. In this case, the production is similar to the embodiment of the Fig. 2, with the difference that here it is advisable to apply only a thin but already fairly uniform layer of adhesive to the bonding area 321, since the adhesive does not have to be forced through bonding openings. However, it is also advantageous to provide a completely light-curable adhesive wall 21 that holds the nozzle disc at its cylindrical outer surface 29. This can be created by shaping adhesive that has oozed out over the outer surface 29 into the desired annular wall 41 with a tool, such as a spatula. Alternatively, after the nozzle disc has been placed and pressed firmly in place, a bead of adhesive is placed circumferentially around the outer surface 29 in an intermediate step and then, if necessary, also shaped into the desired form. In both cases, the adhesive wall 41 is pressed with its radial inner side against the outer side 29 of the nozzle disc in order to achieve a firm and uniform bond after curing.

[0062] The insulating disc 6 fulfils the same function as in the previously described aerosol generators 1', 1 of the Fig. 1 and Fig. 2 and is also glued in the same way in a step following the material connection of nozzle disc 2 and piezoceramic ring 3. List of reference symbols 1, 1' aerosol generator 12 carrier disc 13 vibration generators 2 nozzle disc 21 Central Area 210 nozzle opening 22 Marginal area 220 gluing openings 221 vibration generator facing top of 22 222 underside of 22 facing away from the vibration generator 29 exterior area of ​​2 3, 3' piezoceramic ring 30 concentric through opening of 3, 13 32 nozzle disc facing underside of 3 321 Adhesive area 4 cured adhesive 41 adhesive ring wall 4t thermally curing adhesive 4t1 shift between 22 and 3 4t2 shift between 22 and 5 4o light-curing / light-cured adhesive 5 circular counter washer S rotational symmetry axis of 1, 1' QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] WO 93 / 109100

[0004] EP 2 569 033 B1

[0005] EP 1 762 264 A1

[0006] EP 3 103 497 B1

[0007] WO 2021 / 033128 A1

[0008]

Claims

[1] Aerosol generator, comprising: - a nozzle disc (2) with a central region (21) having a plurality of continuous nozzle openings (210), and - a circular vibration generator (13) with a circular concentric opening (30) which is mechanically coupled to an edge region (22) of the nozzle disc (2) in order to cause the latter to vibrate transversely, the nozzle disc (2) covering the circular opening (30) of the vibration generator (3), characterized by that the vibration generator (13) consists exclusively of a piezoceramic ring (3), wherein the nozzle disc (2) is materially connected with a front side (221) of its edge region (22) by means of a cured adhesive (4) to an adhesive region of an underside (32) of the piezoceramic ring (3). [2] Aerosol generator according to claim 1, wherein the nozzle disc (2) has a plurality of bonding openings (220) in the edge region (22) and the aerosol generator (1) comprises a counter ring (5) which is materially connected via the part (42) of the cured adhesive (4) which has passed through the bonding openings (220) to a rear side (222) of the outer region (22) of the nozzle disc (2). [3] Aerosol generator according to claim 1, wherein it does not comprise a counter ring and the nozzle disc (2) does not have any bonding openings (220) in its outer region (21). [4] Aerosol generator according to one of the preceding claims, wherein the adhesive layer (4) has a thickened annular wall (41) contacting a cylindrical side surface (29) of the nozzle disc (2), in particular being integrally connected thereto. [5] Aerosol generator according to the preceding claim, wherein the annular wall (41) of the adhesive layer (4) has a smooth outer surface (411) inclined at an acute angle relative to the underside (32) of the piezoceramic ring (3). [6] Aerosol generator according to one of the preceding claims, wherein the adhesive (4) is a hybrid adhesive. [7] Aerosol generator according to one of the preceding claims, wherein a thickness of the piezoceramic ring (3) is between 0.3 and 1.0 mm, preferably between 0.4 and 0.6 mm, in particular approximately 0.5 mm. [8] Aerosol generator according to the preceding claim, wherein a diameter of the central region, in particular a dome-shaped region, is between 3 mm and 15 mm, in particular approximately 8 mm. [9] Aerosol generator according to one of the preceding claims 7 or 8, wherein a diameter of the nozzle disc is between 5 mm and 30 mm, in particular approximately 12 mm. [10] Aerosol generator according to one of the preceding claims 7 to 9, wherein an inner diameter of the through opening (30) of the piezoceramic ring (3) is between 4 mm and 28 mm, in particular approximately 8 mm, and an outer diameter of the piezoceramic ring (3) is between 6 mm and 35 mm, in particular approximately 21 mm. [11] Aerosol generator according to one of the preceding claims, wherein it comprises an insulating disc (6) which rests or is glued on an upper side (31) of the piezoceramic ring (3) opposite the underside (32). [12] Aerosol generator according to the preceding claim, wherein the insulating disc: - is made of plastic, - is transparent, - has a thickness of between 0.01 mm and 0.1 mm, in particular approximately 0.05 mm, and / or - is glued to the piezoceramic ring (3) with an adhesive, in particular the same adhesive as the nozzle disc or a light-curing adhesive (4o). [13] Aerosol generator according to one of the preceding claims, wherein the piezoceramic ring (3) consists of a lead-free piezoceramic material. [14] Aerosol generator according to one of the preceding aerosol generator claims, wherein the nozzle disc (2) consists of a stainless steel alloy, in particular one low in nickel. [15] A method of manufacturing an aerosol generator according to any one of the preceding aerosol generator claims, comprising: a. Providing a nozzle disc (2) and a piezoceramic ring (3), b. Applying an uncured adhesive layer (4u) to an annular adhesive area (321) of an underside (32) of the piezoceramic ring (3), c. Placing and pressing the nozzle disc (2) in such a way that it contacts the adhesive layer (4u) with its circular edge area (22), d. Curing of the adhesive (4u) so that it forms a cured adhesive layer (4) which represents a material-locking connection between the nozzle disc and the piezoceramic ring. [16] Method according to the preceding claim, wherein a nozzle disc (2) with an edge region (22) without bonding openings (220) is used and the amount of adhesive is measured such that the adhesive layer (4) bulges out over the cylindrical side surface (29) of the nozzle disc (2) when the nozzle disc (2) is pressed firmly in step c. and forms a thickened annular wall (41) contacting the side surface (9), wherein for this purpose, in particular before the curing of the adhesive in step d., post-processing is carried out such that the annular wall (41) is pressed circumferentially onto the side surface (29) by means of a spatula or another suitable tool and, furthermore, is preferably also smoothed in the process. [17] Method according to claim 13, wherein a nozzle disc (3) with bonding openings (220) in the edge region (22) is used and the amount of adhesive is dimensioned such that it is sufficient to form the adhesive layer (4) between the piezoceramic ring (3) and the nozzle disc (2) as well as the nozzle disc (2) and a counter ring (5) which is also provided and additionally also to fill the bonding openings (22). [18] Method according to one of the preceding method claims, wherein a hybrid adhesive is used as the adhesive and the curing in step d comprises, on the one hand, an active curing by irradiating the areas of the adhesive layer (4u) that can be reached by light rays, in particular an annular wall (41), and furthermore, in particular subsequently, a passive curing of the adhesive (4u). [19] Nebulizer for converting a liquid into a fine-droplet aerosol, comprising an aerosol generator (1) according to one of the aerosol generator claims 1-14 and / or manufactured according to one of the method claims 15-18.

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