Patent Grant
9770728
The present application is a National Stage of International Application No. PCT/EP2011/057378, filed May 9, 2011, which claims priority to European Patent Application No. 10170139.9 filed on Jul. 20, 2010, the entire contents of which are being incorporated herein by reference.
The invention relates to a static spray mixer for the mixing and spraying of at least two flowable components in accordance with the preamble of the independent claim.
Static mixers for the mixing of at least two flowable components are described, for example, in EP-A-0 749 776 and in EP-A-0 815 929. These very compact mixers provide good mixing results, in particular also on the mixing of high-viscosity materials such as sealing compounds, two-component foams or two-component adhesives, despite a simple, material-saving design of their mixer structure. Such static mixers are usually designed for single use and are frequently used for products to be hardened in which the mixer can practically no longer be cleaned.
In some applications in which such static mixers are used, it is desirable to spray the two components onto a substrate after their mixing in the static mixer. For this purpose, the mixed components are atomized at the outlet of the mixer by the action of a medium such as air and can then be applied to the desired substrate in the form of a spray jet or spray mist. In particular more highly viscous coating media, e.g. polyurethane, epoxy resins or similar, can also be processed using this technology.
An apparatus for such applications is disclosed, for example, in U.S. Pat. No. 6,951,310. In this apparatus, a tubular mixer housing is provided which receives the mixing element for the static mixing and which has an external thread at one end onto which a ring-shaped nozzle body is screwed. The nozzle body likewise has an external thread. A conical atomizer element which has a plurality of grooves extending in the longitudinal direction on its cone surface is placed onto the end of the mixing element and projects out of the mixer housing. A cap is pushed over this atomizer element and its inner surface is likewise of conical design so that it contacts the cone surface of the atomizer element. The grooves consequently form flow channels between the atomizer element and the cap. The cap is fixed to the nozzle body together with the atomizer element by means of a retaining nut which is screwed onto the external thread of the nozzle body. The nozzle body has a connection for compressed air. In operation, the compressed air flows out of the nozzle body through the flow channels between the atomizer element and the cap and atomizes the material being discharged from the mixing element.
Even though this apparatus has proved to be absolutely functional, its structure is very complex and the installation is complicated and/or expensive so that the apparatus is in particular not very cost-effective with respect to the single use.
A static spray mixer of much simpler construction is disclosed in the European patent application No. 09168285 of Sulzer Mixpac AG. In this spray mixer, the mixer housing and the atomization nozzle are each configured in one piece, with the grooves forming the flow channels being provided in the inner surface of the atomization sleeve or in the outer surface of the mixer housing.
Starting from this prior art, it is an object of the invention to propose a different static spray mixer for the mixing and spraying of at least two flowable components which is cost-effective in its manufacture and enables an efficient mixing or thorough mixing and atomization of the components.
The subject of the invention satisfying this object is characterized by the features of the independent claim,
In accordance with the invention, a static spray mixer is therefore proposed for the mixing and spraying of at least two flowable components having a tubular mixer housing which extends in the direction of a longitudinal axis up to a distal end which has an outlet opening for the components, having at least one mixing element arranged in the mixer housing for mixing the components and having an atomization sleeve which has an inner surface which surrounds the mixer housing in its end region, wherein the atomization sleeve has an inlet channel for a pressurized atomization medium, wherein a plurality of grooves are provided in the outer surface of the mixer housing or in the inner surface of the atomization sleeve which each extend to the distal end and which form separate flow channels between the atomization sleeve and the mixer housing through which the atomization medium can flow from the inlet channel of the atomization sleeve to the distal end of the mixer housing. The inlet channel is arranged asymmetrically with respect to the longitudinal axis.
A rotational movement about the longitudinal axis can be generated in the atomization medium by this arrangement of the inlet passage which is asymmetrical or eccentric with respect to the longitudinal axis. This swirl has a stabilizing effect on the jet of the atomization medium which emerges at the distal end of the mixer housing. The flow of the atomization medium stabilized by the swirl can in particular have a uniform effect on the mixed components emerging at the distal end of the mixer housing so that a very uniform and in particular also reproducible spraying is made possible. A rotational movement from which a swirl of the atomization medium results is already generated on the inflow of the atomization medium into the atomization sleeve due to the asymmetrical arrangement of the inlet channel.
Since the flow channels are moreover provided in the mixer housing or in the atomization sleeve, a particularly simple structure of the static spray mixer results without compromises in the quality of the mixing or in the atomization being required for this purpose. The ideal use of the individual components allows a cost-effective and economic manufacture of the spray mixers which can moreover be carried out in an—at least largely—automated manner. The static spray mixer in accordance with the invention in principle requires only three components, namely the one-piece mixer housing, the atomizer sleeve and the mixing element, which can likewise be designed in one piece. Low complexity and a simple manufacture and/or assembly results from this.
It has proved particularly advantageous in practice if the inlet channel opens into the inner surface of the atomization sleeve perpendicular to the longitudinal axis.
An advantageous measure lies in the fact that the mixer housing has a distal end region which tapers toward the distal end and wherein the inner surface of the atomization sleeve is designed for cooperation with the distal end region. The atomization effect is improved by this tapering. A conical flow of the atomization medium can in particular thus be realized.
The outer surface of the mixer housing in the distal end region is preferably at least partly configured as a frustoconical surface or as a surface curved in the axial direction to realize a particularly good cooperation with the atomization sleeve.
It has proved to be advantageous with respect to a uniform atomization if the distal end of the mixer housing projects beyond the atomization sleeve.
It is furthermore preferred if the extent of the grooves also has a component in the peripheral direction. The rotational movement of the atomization medium about the longitudinal axis on flowing through the flow channels can be amplified by this measure, which has an advantageous effect on a uniform and reproducible spraying.
A possible embodiment lies in the fact that the grooves have a substantially spiral extent with respect to the longitudinal axis A.
To enable an energy effect of the atomization medium onto the components to be atomized which is as large as possible, the flow channels are preferably configured in accordance with the principle of a Laval nozzle with a flow cross-section which, viewed in the direction of flow, first tapers and subsequently flares. An additional acceleration of the atomization medium, for example to supersonic speed, results from this measure, from which the higher energy input results.
An advantageous measure for realizing the principle of a Laval nozzle is the fact that the grooves, viewed in the direction of flow, narrow with respect to the peripheral direction. In this respect, the peripheral direction means that direction in which the inner surface of the atomization sleeve or the outer surface of the mixer housing extends in the direction perpendicular to the longitudinal axis.
Such a narrowing can also advantageously be achieved in that each groove is bounded by two walls of which at least one is configured as curved, viewed in the direction of flow.
In a preferred embodiment, each flow channel has a respective changing inclination toward the longitudinal axis in the direction of flow.
The flow relationships of the atomization medium can be optimized by the measure of not keeping the inclination of the flow channels constant over their extent, viewed in the axial direction, but rather of changing it in order thus to achieve a particularly uniform and stable effect of the atomization medium onto the mixed components, from which in particular a higher reproducibility of the process also results.
In a first embodiment, the changing inclination of the flow channels is realized in that each groove has three sections arranged after one another, viewed in the direction of flow, wherein the middle section has an inclination toward the longitudinal axis which is larger than the inclination of the two adjacent sections. In this respect, it is particularly preferred if the middle section has an inclination toward the longitudinal axis which is larger than 45° and in particular amounts to less than 50°.
In a second embodiment, the changing inclination is realized in that each groove has a section, viewed in the direction of flow, in which the inclination toward the longitudinal axis changes continuously. In this section, the base of the respective groove is thus configured as curved, which can in particular be realized in that the inner surface of the atomization sleeve or the outer surface of the mixer housing is designed as curved, viewed in the direction of the longitudinal axis.
In particular to simplify the manufacture even further, it is advantageous if the atomization sleeve is connected in a thread-free manner to the mixer housing; for example, the atomization sleeve is fastened to the mixer housing by means of a sealing snap-in connection.
In a preferred embodiment, the mixer housing has a substantially rectangular, preferably square, cross-sectional surface perpendicular to the longitudinal axis (A) outside the distal end region and the mixing element is configured as rectangular, preferably square, perpendicular to the longitudinal direction. The proven mixers which are available under the brand name Quadro® can thereby be used for the static spray mixer.
It is advantageous with respect to a particularly simple and cost-effective manufacture if the mixer housing and/or the atomization sleeve are injection molded, preferably from a thermoplastic.
Further advantageous measures and embodiments of the invention result from the dependent claims.
The invention will be explained in more detail in the following with reference to embodiments and to the drawing. There are shown in the schematic drawing, partly in section:
Reference is made in the following to the case particularly relevant to practice that precisely two components are mixed and sprayed. It is, however, understood that the invention can also be used for the mixing and spraying of more than two components.
The spray mixer 1 includes a tubular, one-piece mixer housing 2 which extends in the direction of a longitudinal axis A up to a distal end 21. In this respect, that end is meant by the distal end 21 at which the mixed components exit the mixer housing 2 in the operating state. The distal end 21 is provided with an outlet opening 22 for this purpose. The mixer housing 2 has a connection piece 23 at the proximal end, which means the end at which the components to be mixed are introduced into the mixer housing 2, and the mixer housing 2 can be connected to a storage container for the components by means of said connection piece. This storage container can, for example, be a two-component cartridge known per se, can be designed as a coaxial cartridge or a side-by-side cartridge or can be two tanks in which the two components are stored separately from one another. The connection piece is designed, depending on the design of the storage container or of its outlet, e.g. as a snap-in connection, as a bayonet connection, as a threaded connection or combinations thereof.
At least one static mixing element 3 is arranged in a manner known per se in the mixer housing 2 and contacts the inner wall of the mixer housing 2 so that the two components can only move from the proximal end to the outlet opening 22 through the mixing element 3. Either a plurality of mixing elements 3 arranged after one another can be provided or, as in the present embodiment, a one-piece mixing element 3 which is preferably injection molded and is made of a thermoplastic. Such static mixers or mixing elements 3 are sufficiently known per se to the skilled person and do not therefore require any further explanation.
Such mixers or mixing elements 3 are in particular suited such as are sold under the brand name QUADRO® by the company Sulzer Chemtech AG (Switzerland). Such mixing elements are described, for example, in the already cited documents EP-A-0 749 776 and EP-A-0 815 929. Such a mixing element 3 of the Quadro® type has a rectangular cross-section, in particular a square cross-section, perpendicular to the longitudinal direction A. Accordingly, the one-piece mixer housing 2 also has a substantially rectangular, in particular square, cross-section perpendicular to the longitudinal axis A, at least in the region in which it surrounds the mixing element 3.
The mixing element 3 does not extend fully up to the distal end 21 of the mixer housing 2, but rather ends at an abutment 25 (see
The static spray mixer 1 furthermore has an atomization sleeve 4 which has an inner surface which surrounds the mixer housing 2 in its end region. The atomization sleeve 4 is designed in one piece and is preferably injection molded, in particular from a thermoplastic. It has an inlet channel 41 for a pressurized atomization medium which is in particular gaseous. The atomization medium is preferably compressed air. The inlet channel 41 can be configured for all known connections, in particular also for a Luer lock.
To enable a particularly simple installation or manufacture, the atomization sleeve 4 is preferably connected to the mixer housing in a thread-free manner, in the present embodiment by means of a snap-in connection. For this purpose, a flange-like raised portion 24 is provided at the mixer housing 2 (see
This snap-in connection is preferably designed in a sealing manner so that the atomization medium—here the compressed air—cannot escape through this connection including the peripheral groove 43 and the elevated portion 24. The inner surface of the atomization sleeve 4 furthermore lies tightly on the outer surface of the mixer housing 2 in a region between the opening of the inlet channel 41 and of the elevated portion 24 so that a sealing effect is also hereby achieved which prevents a leak or a backflow of the atomization medium.
It is naturally also possible to arrange additional sealants, for example an O ring, between the mixer housing 2 and the atomization sleeve 4.
Alternatively to the embodiment shown, it is also possible to provide a peripheral groove at the mixer housing 2 and to provide an elevated portion which engages into this peripheral groove at the atomization sleeve 4.
The connection between the atomization sleeve 4 and the mixer housing 2 is preferably configured so that the atomization sleeve 4 connected to the mixer housing 2 is rotatable about the longitudinal axis A. This is, for example, ensured with a snap-in connection with the completely circumferential peripheral groove 43 and the elevated portion 24. The rotatability of the atomization sleeve 4 has the advantage that the inlet channel 41 can always be aligned so that it can be connected as simply as possible to a source for the atomization medium.
A plurality of grooves 5 are provided in the outer surface of the mixer housing 2 or in the inner surface of the atomization sleeve 4 and each extend toward the distal end 21 and which form separate flow channels 51 between the atomization sleeve 4 and the mixer housing 2 through which the atomization medium can flow from the inlet channel 41 of the atomization sleeve 4 to the distal end 21 of the mixer housing 2. In the embodiment described here, the grooves 5 are provided in the inner surface of the atomization sleeve 4; they can naturally also be provided in accordingly the same manner alternatively or additionally in the outer surface of the mixer housing 2.
The grooves 5 can be configured as curved, for example arcuate, or also as a straight line or also by combinations of curved and straight-line sections.
For the better understanding of the extent of the grooves 5,
To make the exact extent of the grooves 5 of the first embodiment even clearer, in addition to
In the first embodiment, each flow channel 51 or the associated grooves 5 are designed so that, viewed in the direction of flow, it in each case has a changing inclination toward the longitudinal axis A. In the first embodiment, this is realized so that each groove 5 includes, viewed in the direction of flow, three sections 52, 53, 54 arranged after one another (see also
In the middle section 53, which has the largest inclination with respect to the longitudinal axis A, the inclination α2 is preferably larger than 45° and smaller than 50°. In the embodiment described here, the inclination α2 toward the longitudinal axis A in the middle section is 46°. In the first section 52, the inclination α1 amounts to 0° here. In the third section 54, which is at the distal end 21, the inclination α3 toward the longitudinal axis A is preferably smaller than 20°; in the present example, it amounts to approximately 10° to 11°.
Each of the grooves 5 is laterally bounded by two respective walls which are formed by ribs 55 which are each arranged between two adjacent grooves 5. As can in particular be seen from
In accordance with the invention, the inlet channel 41 through which the atomization medium enters into the flow channels 51 is arranged asymmetrically with respect to the longitudinal axis A for the generation of a swirl. This measure can best be recognized in
This swirl has proved advantageous with respect to an atomization of the mixed components exiting the outlet opening which is as complete and as homogeneous as possible. If the compressed air flows exiting the grooves 5 have a swirl, that is a rotation on a helical line about the longitudinal axis A, a clear stabilization of the compressed air flow results. The circulating atomization medium, here compressed air, generates a jet which is stabilized by the swirl and thus acts uniformly on the mixed components exiting the outlet opening 22. A very uniform and in particular reproducible spray pattern results from this. A compressed air jet which is as conical as possible and which is stabilized by the swirl is particularly favorable in this respect. A significantly smaller spray loss (overspray) results in the application due to this extremely uniform and reproducible air flow.
The individual compressed air jets (or jets of the atomization medium) exiting the respective separate flow channels 51 at the distal end 21 are first formed as discrete individual jets on their exit which then combine to form a uniform stable total jet due to their swirl property, said total jet atomizing the mixed components exiting the mixer housing. This total jet preferably has a conical extent.
The grooves 5, there are eight grooves 5 in this embodiment, are distributed uniformly over the inner surface of the atomization sleeve 4. To amplify the swirl in the flow of the atomization medium, further advantageous measures are possible. The grooves 5 which form the flow channels 51 do not extend exactly in the axial direction defined by the longitudinal axis A or do not only extend inclined toward the longitudinal axis, but the extent of the grooves 5 also has a component in the peripheral direction of the atomization sleeve 4. This can in particular be seen from the representation in
It is alternatively also possible that the flat region 271 is configured with a conical angle of 0°, that is the flat region 271 is then of cylindrical design. In the flat region 271, the outer surface of the mixer housing 2 is then the jacket surface of a cylinder whose cylinder axis coincides with the longitudinal axis A.
As
The inner surface of the atomization sleeve 4 is designed to cooperate with the distal end region 27 of the mixer housing 2. The ribs 55 of the atomization sleeve 4 provided between the grooves 5 and the outer surface of the mixer housing 2 lie close and sealingly with respect to one another so that the grooves 5 form a respective separate flow channel 51 between the inner surface of the atomization sleeve 4 and the outer surface of the mixer housing 2 (see
Further upstream, in the region of the opening of the inlet channel 41 (see also
To increase the energy input from the atomization medium to the components exiting the outlet opening 22, it is a particularly advantageous measure to configure the flow channels 51 in accordance with the principle of a Laval nozzle having a flow cross-section first narrowing and subsequently flaring, viewed in the direction of flow. To realize this narrowing of the flow cross-section, two dimensions are available, namely the two directions of the plane perpendicular to the longitudinal axis A. The one direction is called the radial direction, by which the direction is meant which stands perpendicular on the longitudinal axis A and which faces outwardly radially from the longitudinal axis A. The other direction is called the peripheral direction, by which the direction is meant which stands perpendicular both on the direction defined by the longitudinal axis A and on the radial direction. The extent of the flow channels 51 in the radial direction is called their depth.
The principle of the Laval nozzle can be realized with respect to the radial direction in that the depth of the flow channels 51 greatly reduces in the middle steep section 53. The depth becomes minimal where the transition from the flat region 271 into the steeper region 272 takes place at the mixer housing 2. Downstream of this transition, the depth of the flow channels 51 increases again, mainly due to the fact that here the outer surface of the mixer housing 2 is part of a steeper truncated cone and the inclination of the inner surface of the atomization sleeve 4 remains substantially constant in the third section 54. A Laval nozzle can be achieved with respect to the radial direction by this measure.
In addition or also alternatively, the flow channels 51 can also be configured in accordance with the principle off a Laval nozzle with respect to the peripheral direction. This can best be recognized in the representation of
The air used as the atomization medium can also additionally be acted on by kinetic energy downstream of the narrowest point and can thus be accelerated by the configuration of the grooves 5 or of the flow channels 51 in accordance with the principle of a Laval nozzle. This is done as with a Laval nozzle by the flow cross-section again widening in the direction of flow. A higher energy input into the components to be atomized results from this. In addition, the jet is stabilized by this realization of the Laval principle. The diverging opening, that is the opening which widens again, of the respective flow channel 51 moreover has the positive effect of an avoidance or of at least a considerable reduction of fluctuations in the jet.
In operation, this first embodiment works as follows. The static spray mixer is connected by means of its connection piece 23 to a storage vessel which contains the two components separate from one another, for example with a two-component cartridge. The inlet channel 41 of the atomization sleeve 4 is connected to a source for the atomization medium, for example to a compressed air source. The two components are now dispensed, move into the static spray mixer 1 and are there intimately mixed by means of the mixing element 3. After flowing through the mixing element 3, the two components move as a homogeneously mixed material through the outlet region 26 of the mixer housing 2 to the outlet opening 22. The compressed air flows through the inlet channel 41 of the atomization sleeve 4 into the ring space 6 between the inner surface of the atomization sleeve 4 and the outer surface of the mixer housing 2, has a swirl imparted onto it in this process by the asymmetrical arrangement and moves from there through the grooves 5 which form the flow channels 51 to the distal end 21 and thus to the outlet opening 22 of the mixer housing 3. The compressed air flow stabilized by the swirl here impacts the mixed material exiting the outlet opening 22, atomizes it uniformly and transports it as a spray jet to the substrate to be treated or to be coated. Since the dispensing of the components from the storage vessel takes place with compressed air or supported by compressed air in some applications, the compressed air can also be used for the atomization.
An advantage of the static spray mixer 1 in accordance with the invention is to be seen in its particularly simple construction and manufacture. In principle, only three parts are required in the embodiment described here, namely a one-piece mixer housing 2, a one-piece mixing element 3 and a one-piece atomization sleeve 4, with each of these parts being able to be manufactured in a simple and economic manner by means of injection molding. The particularly simple construction also enable an—at least largely—automated assembly of the parts of the static spray mixer 1. In particular no screw connections of these three parts is necessary.
It is advantageous with respect to a particularly simple and cost-effective manufacture if the mixer housing and/or the atomization sleeve are injected molded, preferably from a thermoplastic.
For the same reason, it is advantageous if the mixing element is designed in one piece and is injection molded, preferably from a thermoplastic.
In the following, a second embodiment of the static spray mixer in accordance with the invention will be explained with reference to
A changing inclination of the flow channels 51 toward the longitudinal axis A is also realized in the second embodiment; however, by a continuous change. For this purpose, the atomization sleeve 4 has a section 56 (see
To amplify the swirl movement, the flow channels 51 extend spirally about the longitudinal axis A, with their extent reducing in the peripheral direction in section 56, viewed in the direction of flow.
It is understood that the measure in accordance with the invention of arranging the inlet channel 41 asymmetrically with respect to the longitudinal axis A in order thus to generate a swirl movement on the inflow of the atomization medium is not restricted to the embodiments of a spray mixer described here, but can rather also be used for other embodiments. The asymmetrical arrangement of the inlet channel 41 is in particular also suitable for such static spray mixers as are disclosed in the already quoted European patent application No. 09168285 of Sulzer Mixpac AG.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10170139 | Jul 2010 | EP | regional |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2011/057378 | 5/9/2011 | WO | 00 | 1/18/2013 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2012/010337 | 1/26/2012 | WO | A |
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| Number | Date | Country | |
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| 20130112778 A1 | May 2013 | US |
