EP2111917A1 - Static mixer, method for manufacturing the same, and mixer assembly - Google Patents

Abstract

The static mixer (10) has rods (13) running transverse to the stream direction and has guiding elements (14) inclined from the rods coming out in the stream direction. The mixer is formed in single piece, cup-shaped with a base area (11) and a side wall area (12) running in flow direction. The rods, an edge area (17) and the guiding elements are formed and contact the rods only at their ends. An independent claim is included for a method for manufacturing a static mixer.

Description

The present invention relates to a mixer for mixing at least one fluid stream in a pipe section. The invention further relates to a mixer arrangement comprising at least two such mixers, which are arranged one behind the other in a pipe section and a method for producing such a mixer.

Static mixers are used to fluidize one or more fluid streams flowing in a pipe section.

The term fluid stream as used herein is intended to include those streams in which, for example, small droplets or particles are transported in a fluid stream.

Static mixers are used eg in waste gas purification. In this case, a reaction medium is injected into an exhaust gas stream which flows in a pipe section (for example from an internal combustion engine) via a probe (for example urea for NO x reduction). Subsequently, exhaust stream and reactant are fed to a catalyst in which the desired reaction takes place for the exhaust gas treatment. In order for the most complete and uniform reaction to take place in the entire exhaust gas stream, the exhaust gas stream and reactant stream are mixed as completely as possible with one another before they enter the catalyst. Only in this way can the reagent be dosed correctly and the catalyst surfaces can be used optimally for the reaction. The static mixer (s) are intended to mix the exhaust stream and the reactant stream largely homogeneously with one another on a flow path that is as short as possible, and thereby build up the lowest possible flow resistance. In addition, especially in the automotive sector costs and thus manufacturing aspects play a major role; that is, the static mixer should be as inexpensive to produce.

At one of the DE 10 2006 024778 B3 known static mixer a plurality of transverse to the flow direction layers of a wave-shaped strip material are provided, which forms a plurality of flow-through cells, wherein on the downstream side (outlet side of the flow) of the cells curved flow control surfaces are provided which extend in the flow direction and transverse thereto and thus the mixing and fluidizing fluid streams passed through the cells.

A similar static mixer is in FIG. 11 shown. Here lattice-shaped crossed, durchströmbare cells forming laminations are provided, which are provided on the downstream side tongue-shaped, planar flow guide, mix the fluid streams passing through the grid cells with each other and swirl. The grid-like arranged lamellae are fixed in a tubular support section.

Both versions represent effective and aerodynamically mature static mixer. However, they require a relatively high production cost and are therefore expensive.

From the DE 197 41 199 A1 a simple constructed, static mixer is known in which a so-called. Expanded mesh is arranged in the pipe cross-section of a flow channel and a flow around the lattice struts and nodes generates the mixing of fluid flows causing vortex and turbulence. For improved mixing, such a grid can also be arranged inclined to the direction of flow. It is also provided to arrange several such gratings one behind the other. However, this may be disadvantageous in terms of flow, since under certain circumstances a high pressure drop in the flow may occur when passing through the expanded metal grid arrangement. Thus, if necessary, the flow characteristics, which should be precisely matched, in particular in the exhaust system of a motor vehicle, are disturbed too much.

From the DE 43 13 393 A1 a static mixer arrangement is known in which in each case a plurality of trapezoidal deflection elements are arranged in transverse to the flow direction rows. The deflection elements are inclined in each row parallel to each other in the flow direction. In each case adjacent rows are provided in pairs, the deflection elements are offset from one another in the longitudinal direction and inclined in opposite directions. The rows carrying the deflecting elements are in each case brought into contact with each other back to back and installed in pairs in a carrier grid. In this case, a plurality of rows of deflection elements and carrier grid elements are joined together to form a static mixer. Similar mixer arrangements with transverse to the flow direction webs and arranged thereon deflecting elements are also from the US 5,605,399 known.

From the DE 35 36 315 A1 a so-called swirl body is known in which from a standing perpendicular to the flow direction base plate vanes are partially punched out and bent, which project helically in the flow direction and imparting in the resulting openings exhaust gases in addition to their flow direction, a rotation pulse (twist). However, such spin bodies are suitable only to a limited extent for mixing two gas streams / fluid streams. The possibly desired cyclone effect for the separation of solid particles located in the fluid flow causes only a comparatively small mixing of the fluid flow.

A similar arrangement is from the WO 03/036056 A1 known in the opposing oriented baffles two concentric generate mutually flowing currents with opposite direction twist and thus cause a mixing of several fluid streams. Although the two last-mentioned embodiments can be produced in a cost-effective stamping process. However, there are fluidic restrictions, since here - in relation to the guide surfaces - relatively large transverse to the flow direction of the disturbance surfaces, the pressure drop between the inflow and outflow can be significant.

The object of the present invention is to provide an improved static mixer. It is particularly desirable in this case to combine good mixing properties, favorable flow conditions and a structurally or production-technically favorable design.

This object is achieved by the mixer having the features of claim 1, a mixing arrangement according to claim 11 and a method for producing the mixer according to claim 12.

The mixer according to the invention has webs running transversely to the flow direction, from which guide elements inclined to the flow direction emanate. In this case, the webs pass through the flow cross section without touching each other, and the guide elements and webs are integrally connected to each other. Such a mixer makes it possible to combine a simple construction with comparatively favorable flow properties and a good mixing characteristic.

In this case, a production technology particularly favorable press-stamping-punching component is realized, which is additionally stabilized on the sidewall area. It can simply be inserted into a corresponding piece of pipe without tilting it during insertion.

Such a mixer leads to the inherent divergent demands for low pressure drop when flowing through the mixer, an effective mixing of a fluid flow on one short route and a manufacturing technology favorable and therefore cost-effective design together.

The features of claims 2 to 8 relate to manufacturing technology and functionally advantageous solutions.

According to claim 2, the guide elements are each coupled along a Kantlinie with the web. Thus, the areas web and guide element are functionally separated from each other; the webs form the support structure and the guide elements the actual mixing structure. However, they can still be prefabricated together from one piece (for example punched out). The machining is possible with comparatively simple punching and embossing tools. The pre-cut guide elements can be folded from the web along the respective edge line and be employed with different inclinations in the fluid flow.

According to claim 3, a plurality of guide elements are each provided side by side, so that for mixing a plurality of tongue-like guide elements laschen- or spoon-shaped can be provided on the webs, which are independently deformable along their respective Kantlinie to the web. Thus, differently designed guide elements with different inclinations 15 ° to 45 ° at different locations in the flow cross section can be realized. The mixer can thus also be adapted to a specific flow entry profile. The mixing properties can be varied over the flow cross-section. If the canted lines are offset parallel to one another, as indicated in claim 4, this effect can be further improved.

According to claim 5, the guide elements may also be formed like a louver along the entire length of a web for a particularly simple and low-production design. This further simplifies the required production steps and tools.

By a convex or concave shape of the guide elements with respect to the flow direction according to claim 6 positive flow effects can be achieved in addition, which reduce the flow resistance and / or improve the mixing properties.

According to claim 7, the formations are provided on correspondingly arranged creases. This design allows a repeatable production with relatively simple tools.

The specified in claim 8 ratio between the land width and the web thickness is advantageous in view of the particularly cost punch-stamping production and provides a high structural stability.

By according to claim 9, the webs interconnecting edge region is a stable mixer can be displayed, which is used as a complete, one-piece producible, disc-shaped component in predetermined pipe cross-sections.

The webs and the edge region define an end face pointing in the flow direction, and turbulence surfaces inclined to the flow direction are provided on the guide elements. According to claim 10 thereby form the end face and the sum of the inclined Verwirbelungsflächen a ratio of 0.8 to 0.35 and preferably a ratio of 0.5 to 0.4. The face and swirl surfaces cover a range of 50% to 75% of the flow cross-section.

The mixing arrangement according to claim 11 can significantly increase the mixing quality, so that the mixing length, that is, the required length of the pipe section, in which the fluid streams are to mix, is shortened. For this purpose, the proposed mixer can be designed differently. But it is also possible to improve by a different arrangement of identical mixer to each other, the desired mixing result. For this purpose, the individual mixers for Flow direction inclined and / or be arranged rotated in the circumferential direction to each other.

The methods according to claims 12 and 13 relate to particularly favorable and cost-saving production methods for a mixer according to the invention.

Figur 1

ein erstes Ausführungsbeispiel eines erfindungs- gemäßen Mischers in einer perspektivischen Ansicht,

Figur 2

den Mischer aus Figur 1 in einer Seitenansicht,

Figur 3

eine Ansicht in Richtung B des in Figur 1 und 2 dargestellten Mischers,

Figur 4

ein zweites Ausführungsbeispiel eines erfindungs- gemäßen Mischers in einer perspektivischen Ansicht,

Figur 5

ein drittes Ausführungsbeispiel eines erfindungs- gemäßen Mischers in einer perspektivischen Ansicht,

Figur 6

ein viertes Ausführungsbeispiel eines erfindungs- gemäßen Mischers in perspektivischer Ansicht,

Figur 7

ein fünftes Ausführungsbeispiel eines erfindungs- gemäßen Mischers in perspektivischer Ansicht,

Figur 8

ein sechstes Ausführungsbeispiel eines erfindungs- gemäßen Mischers in perspektivischer Ansicht,

Figur 9

eine Schnittdarstellung einer Mischeranordnung mit zwei zueinander verdrehten Mischern gemäß Figur 7,

Figur 10

ein Ablaufdiagramm eines erfindungsgemäßen Herstel- lungsverfahrens,

Figur 11

einen aus dem Stand der Technik bekannten Mischer, und

Fig. 12

ein siebtes Ausführungsbeispiel eines erfindungs- gemäßen Mischers in perspektivischer Ansicht.

Embodiments of the present invention will be explained below with reference to the drawings. It shows

FIG. 1

A first embodiment of a mixer according to the invention in a perspective view,

FIG. 2

the mixer off FIG. 1 in a side view,

FIG. 3

a view towards B of in FIGS. 1 and 2 shown mixer,

FIG. 4

A second embodiment of a mixer according to the invention in a perspective view,

FIG. 5

A third embodiment of a mixer according to the invention in a perspective view,

FIG. 6

A fourth embodiment of a mixer according to the invention in a perspective view,

FIG. 7

A fifth embodiment of a mixer according to the invention in a perspective view,

FIG. 8

A sixth embodiment of a mixer according to the invention in a perspective view,

FIG. 9

a sectional view of a mixer arrangement with two mutually rotated mixers according to FIG. 7 .

FIG. 10

a flowchart of a production method according to the invention,

FIG. 11

a known from the prior art mixer, and

Fig. 12

a seventh embodiment of a mixer according to the invention in a perspective view.

A first embodiment of a mixer 10 according to the invention is in the FIGS. 1 to 3 shown. The mixer 10 is made in a deep-drawing stamping process and has a cup-like shape. The mixer 10 has a bottom portion 11 and a side wall portion 12. In the bottom area 11, a plurality of webs 13 run alongside one another without contact, on which tab-like guide elements 14 are formed.

These guide elements are inclined at an angle of 15 ° to 45 ° to the flow direction B, parallel to the in FIG. 2 shown center axis 15 extends. The guide elements 14 are each alternately and in the longitudinal direction of the webs 13 offset from each other in different directions from the webs 13 from. They are connected along the ridge lines 16 with the webs. Seen in the longitudinal direction of the webs ( FIG. 2 ), the ends of the guide elements 14 are arranged entangled with each other. In the exemplary embodiment shown, the guide elements 14 have a trapezoidal shape tapering towards the free ends, in which the transition areas between the lateral flanks of the guide elements 14 and the end edge are rounded.

The webs 13 themselves are connected to each other in the bottom region 11 via an edge region 17, which merges rounded into the side wall region 12 formed as a pipe section.

The mixer 10 is preferably in the direction B ( FIG. 2 ) flows through the one or more fluid streams or streams to be mixed together. Here is the facing in the direction of flow B face 18, which is from the corresponding surface portions of the edge portion 17, the webs 13 and the extensions 13a composed, in a ratio to the also pointing in the flow direction Verwirbelungsflächen 19 on the guide elements 14 of 0.8 to 0.35 and preferably in a ratio of 0.5 to 0.4. In this case, the surfaces of the guide elements 14 projected into the ground plane are considered to be the swirling surface.

Web width b and the web thickness S and the material thickness of the mixer are in a ratio of 2: 1 to 1: 1. In these proportions, the guide elements 14 can be clean along the edge lines 16 of the webs 13, without them from their level Be bent out.

In the mixer 10, the canted lines 16 and the corresponding web sections are offset parallel to one another and transversely to the web course. In this way, the desired Verschränkungsmaß is achieved in the folded guide elements 14, which improves the turbulence of the flow passing through.

There are also embodiments in which the canted lines 16 are not parallel but at an angle to each other.

The mixer 10 is preferably made of a thermoformable sheet material. When used in a vehicle exhaust system, austenitic steel materials, e.g. in qualities such as 1.4301 or similar, in output wall thicknesses of 0.75 to 3 mm. The diameter of the illustrated mixer is typically 50 to 75 mm.

FIGS. 4 and 5 show variants 20 and 30 of the in the FIGS. 1 to 3 illustrated mixer 10th

The mixer 20 according to FIG. 4 has slightly modified vanes 24, which are curved so that the concave side facing the swirling surface 29 in the flow direction and the curvature about a transverse to the creases 16 from the neck region the guide elements 24 extends to its end extending bending line 25.

The in FIG. 5 shown mixer 30 also has curved guide elements 34, in which the curvature takes place around the bending line 25. However, it is designed in the other direction, so that here has the convex side with the swirling surface 39 in the flow direction. In addition to the in FIGS. 4 and 5 illustrated one-dimensional curvature of the guide elements 24 and 34 can also be a two-dimensional curvature or curvature of the guide elements are provided, in which they are then formed more or less spoon-shaped.

In other embodiments, not shown, both the shape and size, and the inclination, as well as the curvature of individual guide elements 14, 24 or 34 may be formed individually different. As a result, the mixing properties can be individually matched to a stationary inflow profile and optimized.

Fig. 12 shows a mixer 70, the bottom portion 71 is divided into two parts. The edge bottom portion 71a includes a rim with outer vanes 74a. These are aligned in the circumferential direction and exposed along radially extending canted lines 76a so that they give a swirl pulse when flowing through the outer edge region of the flow. The central bottom portion 71b has transversely extending webs 73 on which the guide elements 74b are formed and arranged similar to those in connection with the Fig. 1, 3rd and 4 described guide elements 14, 24 and 34th

In another embodiment, not shown, the outer guide elements 74a can also be issued in pairs starting from a common edge line 76 against each other, so that no swirling action then arises in the edge bottom portion 71a.

In other embodiments, not shown, the central bottom portion 71 b may also be formed as in connection with the embodiments according to the Fig. 6 . 7 and 8 will be described below.

FIG. 6 shows an embodiment of a mixer 40, in which the guide elements 44 are formed like a louver along the entire length of the webs 43. These guide elements 44 are also arched along a bending line 45 that runs parallel to the canted line 46. In this case, the ends of the guide elements 44, which originate from adjacent webs 43, face each other.

FIG. 7 shows a similar mixer 50, in which the guide elements 54, however, are arranged without additional curvature as grade tabs along the channel lines 56 which extend along the webs 53.

When in FIG. 8 shown mixer 60 is provided at each web 63, only a single lamellar guide member 64. The guide elements 64 are all oriented in the same direction and issued along the edge lines 66 from the floor area level.

FIG. 9 shows a mixer assembly 100, in which two mixers 50 are arranged in a pipe section 101. The two mixers 50 are here inserted rotated 90 degrees to each other and arranged one behind the other along the flow axis 15. The distance of the mixer 50 to each other can be chosen so that an optimal mixing result occurs. The sidewall region 52 permits the clean insertion of the mixers 50 into the tube section 101 without tilting the cross-sectional planes (mixing planes) defined by the bottom regions 51.

In other mixer arrangements, not shown, different mixers can be combined. It is also possible, in addition to the twisted arrangement the mixer 10, 20, 30, 40, 50, 60 with extending in different inclined planes floor areas - so obliquely - to arrange in a pipe section 101.

There continue to be designs in which the mixers are formed without sidewall region. Such mixers are then designed more or less disk-shaped, in which only the edge region connects the webs with each other. Such a disc-shaped mixer can then for example be placed on a pipe end or inserted between two pipe ends. It is also possible to use such a disk-shaped mixer in a corresponding receiving slot of a pipe section.

FIG. 10 shows the sequence of a method for producing the mixer 10. For this purpose, a suitable semi-finished product is first provided, which in the present case is a flat sheet metal material, which is provided as a single piece of sheet metal or as a continuous sheet strip (coil material). Then the outer contour is cut out. This can happen mechanically, thermally or abrasive depending on the material used. Suitable working processes are, for example, stamping, plasma cutting or water jet cutting.

The cup form is produced in a drawing or deep-drawing process, in which the semifinished product is plastically deformed using a die and a male part, so that it comes close to the desired final shape after the molding process. In a second postforming process, the geometry is further approximated. For example, the transition radii between the sidewall region 12 and the bottom region 11 in the edge region 17 are reduced.

Next, the contours of the webs 13 and the guide elements 14 are defined. By a two-step hole process ensures that no unwanted plastic deformation of the webs 13 and the guide elements 14 take place. The two-stage punching has the further advantage that the tool geometries for possibly required punching tools are simplified and the relatively complex web-Leitelementkontur clean and repeatable to produce.

In the last working step determining the actual mixer geometry, the guide elements 14 are tilted along the edge lines and deformed relative to the webs 13.

In addition, if necessary, the individual mixers 10 can be separated from a guide strip required for processing. Possibly. Work can also be done on deburring or calibrating the finished parts. In a final surface treatment, for example, a corrosion protection can be applied.

If necessary, the individual work steps can be supplemented by further steps, for example in the case in which the guide elements as in the FIGS. 4, 5 and 6 shown additionally deformed. There are also cases in which steps are omitted, for example, when the mixer disc-shaped, that is, without the side wall portion 12 are executed. In this case, the steps "drag" and "reshape" are eliminated. For simple geometries of the guide elements (see. Fig. 6 . 7, 8 ), the punching can also be carried out in one stage or together with the "tilting".

Further modifications and variations of the present invention will become apparent to those skilled in the art within the scope of the following claims.

Claims (13)

A static mixer (10; 20; 30; 40; 50; 60; 70) for mixing at least one fluid stream over a flow cross-section in a pipe section (101), with
transverse to the flow direction webs (13; 43; 53; 63; 73) and
extending from these webs to the flow direction inclined guide elements (14; 24; 34; 44; 54; 64; 74b),
characterized in that the mixer (10; 20; 30; 40; 50; 60; 70) is formed integrally, cup-shaped with a bottom portion (11) and a side wall portion (12) extending in the flow direction, the webs (13; 43; 53; 63; 73), the edge region (17) and the guide elements (14; 24; 34; 44; 54; 64; 74a; 74b) are formed integrally from the bottom region (11) and the webs (13; 43; 53, 63, 73) may only touch at their ends. A mixer (10; 20; 30; 40; 50; 60; 70) according to any one of the preceding claims, wherein the guide elements (14; 24; 34; 44; 54; 64; 74b) are each along a crease line (16; 46; 56; 66) are connected to a web (13; 43; 53; 63; 73). A mixer (10; 20; 30; 40; 50; 70) according to any one of claims 1 and 2, wherein each of a plurality of guide elements (14; 24; 34; 44; 54) along different crease lines (16; 46; 56) with a Web (13; 43; 53; 73) are connected. Mixer (10; 20; 30; 70) according to Claim 3, in which the edge lines (16) extend in sections offset from each other in sections. A mixer (40; 50; 60; 70) according to any one of claims 1, 2 or 3, wherein the guide elements (44; 54; 64) are each formed like a louver along the entire length of a web (43; 53; 63; 73). Mixer (20; 30; 40; 70) according to one of the preceding claims, in which the guide elements (24; 34; 44; 74b) have a convex and / or concave shape relative to the flow direction (B). A mixer (20; 30; 40; 70) according to claim 6, wherein the molding is formed along at least one further crease line (25; 45) on the guide element. A mixer (10; 20; 30; 40; 50; 60; 70) according to any one of claims 1 to 7, wherein the web width (b) in the disk plane and the web thickness (S) perpendicular to the disk plane in a ratio of 2: 1 to 1: 1 stand. A mixer (10; 20; 30; 40; 50; 60; 70) according to any one of claims 1 to 8, wherein the webs (13; 23; 33; 43; 53; 63; 73) are integral with one of the ends thereof Webs interconnecting edge region (17) are formed. A mixer (10; 20; 30; 40; 50; 60; 70) according to any one of claims 1 to 9, wherein the webs (13; 43; 53; 63; 73) and the peripheral region (17) have a downstream end surface (18) and the guide elements (14; 24; 34; 44; 54; 64; 74a; 74b) define a swirling surface (19; 29; 39) inclined to the flow direction (B), wherein the end face (18) faces the swirling surface (19 29, 39) in a ratio of 0.8 to 0.35 and preferably in a ratio of 0.5 to 0.4 and frontal and Verwirbungsfläche (18, 19, 29, 39) together 50% to 75% cover the flow cross-section. Mixing arrangement (100) with at least two mixers (10; 20; 30; 40; 50; 60; 70) according to one of the preceding claims, which are arranged one behind the other in the flow direction in a pipe section (101),
wherein the mixers are each formed differently and / or differently aligned with each other. A method of making a mixer (10; 20; 30; 40; 50; 60; 70) according to any one of claims 1 to 11, comprising: - Providing a sheet material - Punching a shape defining the mixer shape outer contour - Forming a side wall portion in a deep-drawing process for forming a cup shape - First punching a webs and guiding elements defining inner contour - Forming the guide elements along the webs extending Kantlinien The method of claim 12 additionally comprising: - Convex and / or concave shaping of the guide elements to the flow direction along at least one bending line (25; 45).

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