DE102016111726B4 - mixing device - Google Patents

Abstract

Mixing device (11) for distributing and vaporizing a fluid in an exhaust gas stream, with a particular tubular body (13), at the axial ends of each at least one radially inwardly projecting gas guide vane (15A, 15B) is arranged to an upstream and a downstream mixer stage (17A, 17B) axially spaced from each other, characterized in that at least one of the gas vanes (15B) of one of the mixer stages (17B) is provided with at least two separate surface segments (28, 30) to form a third mixer stage (17C) which are angled along a folding edge (35) relative to each other, wherein the surface segments (28, 30) which form the third mixer stage (17C) have a free end portion disposed in at least two and preferably exactly two juxtaposed and by a Slit (49) separated strips (27, 28) is divided, with respect to a longitudinal axis (A) of the base body (13) under are well hired.

Description

The present invention relates to a mixing device for distributing and vaporizing a fluid in an exhaust gas stream, having a main body, in particular tubular, at the axial ends of which at least one radially inwardly projecting gas guide vane is arranged to form an upstream and a downstream mixer stage which are axially spaced from each other. The present invention further relates to a method for producing such a mixing device

Such a mixing device is known from EP 2 769 762 A1 known. Other mixing devices are also in the DE 10 2008 017 395 A1 . US 2015/0013313 A1 . DE 10 2014 006 491 B3 or DE 10 2007 028 449 A1 disclosed.

Mixing devices are also referred to as "static mixer" and serve, for example, in exhaust systems of diesel engines an injected reducing agent such. B. to distribute a water-urea mixture to reduce by means of the so-called selective catalytic reduction of nitrogen oxides in the exhaust gas. For achieving a high efficiency in the reduction, it is important that the reducing agent is mixed on the one hand as evenly as possible with the exhaust gas and on the other hand, as completely evaporated. The gas guide vanes of the mixing device serve in this sense on the one hand to produce a turbulence and / or a twist in the exhaust stream and on the other hand act as evaporator surfaces.

Common mixing devices can be manufactured by soldering metal individual components. However, this is associated with a high production cost.

The invention has for its object to provide a simple and inexpensive to produce mixing device with high degree of mixing and good evaporation performance.

The object is achieved by a mixing device having the features of claim 1.

According to the invention, at least one of the gas guide vanes of one of the mixer stages for forming a third mixer stage is provided with at least two separate surface segments which are angled along a fold edge relative to one another. The invention thus provides a three-stage or multi-stage folding mixer. Due to the additional mixer stage results in an increase of the Verwirbelungseffekts and an increase in the evaporator surface. Of particular advantage here is that the third mixer stage can be generated by bending, folding or bending, so that a complex soldering is not required. By varying the size ratios of the separate surface segments and the degree of angling of the surface segments relative to the gas guide vane and / or relative to one another, a mixing device according to the invention can be easily adapted to different flow and injection parameters.

According to one embodiment of the invention, the two separate surface segments are each set against a longitudinal axis of the base body, preferably at an angle of at least 20 ° and at most 60 °, and more preferably at an angle of at least 30 ° and at most 50 °. Such employed gas guide vanes produce sufficiently strong turbulence in the exhaust gas flow, which promote a uniform distribution of the fluid.

The two separate surface segments may each be at least substantially planar. This allows a particularly simple production of the mixing device. In principle, however, the separate surface segments can also have a curved course.

Preferably, the at least one gas vane forming the third mixer stage is disposed at a downstream end of the downstream mixer stage. In order to produce such a designed mixing device, for example, in a two-stage mixer, the downstream end of the downstream mixer stage can be folded, which is manufacturing technology relatively easy to accomplish.

A further embodiment of the invention provides that, to form the third mixer stage, an arrangement of a plurality of gas guide vanes distributed along the pipe circumference of the tubular base body is provided, wherein each of the distributed gas guide vanes has two separate surface segments which are angled relative to one another along a respective folding edge. Preferably, the gas vanes of the third mixer stage are arranged distributed uniformly along the tube circumference and / or directly adjacent to each other. This has proven to be particularly favorable in terms of distribution and evaporation effect.

The distributed arranged gas guide vanes may be arranged to produce a twist in the exhaust gas flow turbine-like. This allows effective swirl generation with a large evaporator surface.

The folding edge preferably runs at right angles or at an angle to a longitudinal axis of the main body. In particular, in the case of a substantially tubular main body, the folded edge can run at right angles or obliquely to the tube axis. Such folded gas guide vanes provide a particularly large evaporator surface. If desired on the basis of the application specifications, the folding edge can alternatively also run parallel to the longitudinal axis of the base body.

The third mixer stage may have three separate surface segments that are angled along two fold edges relative to each other. This allows a particularly effective turbulence of the exhaust gas flow.

Preferably, the two folding edges run along intersecting straight lines, as this has proven to be advantageous in terms of turbulence. In principle, the two folding edges could also run along parallel straight lines. There may also be more than three area segments for one or all of the elements of the third mixer stage to further enhance the distribution and evaporation effect.

According to the invention, the surface segments which form the third mixer stage have a free end region which is divided into at least two and preferably exactly two juxtaposed strips separated by a slot and which are set to different degrees with respect to a longitudinal axis of the base body. The turbulence generation is thereby further improved.

A special embodiment of the invention provides that the gas guide vane of the upstream and / or the downstream mixer stage comprises two separate surface elements which are angled along a folding edge relative to each other and which are arranged in particular in the axial direction one behind the other. The additional mixer stage is created in this embodiment in a simple manner by bending the gas guide vane of an existing mixer stage.

It can be provided that the at least one gas guide vane (or surface portions thereof) of the first mixer stage is employed with respect to the longitudinal axis by an angle of attack of less than 20 °. The angle of attack can be adapted to the respective application. However, a comparatively low angle of attack is to be preferred in order to avoid excessive deflection losses and flow accelerations.

The base body may have a lateral surface, from which at least one surface piece is bent out as an additional guide element (in particular inwards). Such a guide element ensures a further increased mixing and evaporation performance and may optionally form an additional mixer stage.

The main body, the gas guide vanes and / or the surface segments may be formed by forming from a one-piece sheet metal component. This allows a particularly cost-effective production, since no or at least significantly less of the complex soldering must be used. A particularly simple production can be achieved in that the mixing device is performed as a whole in one piece.

The base body, the gas guide vanes and / or the surface segments can be made of a composite material, in particular of a plated copper-stainless steel connection. Such special materials can generally not or only with difficulty be used in to be soldered mixer components.

It is preferably provided that the base body has a polygonal, in particular a hexagonal, cross-section and / or that the base body is formed by circumferentially adjacent planar surface portions. The creation of the gas guide vanes in folding technique is facilitated.

A specific embodiment of the invention provides that a section of a free end of the gas turbine blade or surface segment forming the third mixer stage has a groove. This has proven to be advantageous in terms of flow.

The main body and / or the gas vanes may be electrically heated to allow for even more effective evaporation. In particular, an electrical short-circuit method can be used for this purpose.

It is understood that numerous more constellations of three or more stages folding mixer can be created by the principle of multiple folding or bending in the same or opposite direction.

• - Bereitstellen eines flächigen Rohbauteils,
• - Einschneiden von Schlitzen an zwei gegenüberliegenden Seiten des Rohbauteils, um jeweils durch die Schlitze getrennte Segmente zu bilden,
• - Abwinkeln der Segmente gegenüber einer Basisfläche des Rohbauteils entlang jeweiliger Biegekanten, und
• - Biegen des Rohbauteils zu einem rohrförmigen Körper, an dessen axialen Enden jeweils wenigstens eine radial nach innen ragende, durch ein abgewinkeltes Segment gebildete Gasleitschaufel angeordnet ist,

wobei wenigstens eines der Segmente zumindest einmal entlang einer weiteren Biegekante in sich geknickt wird.The invention also relates to a method for producing a mixing device for distributing and evaporating a fluid in an exhaust gas flow, in particular as described above, with the steps:

• Providing a flat shell component,
• - Slitting slots on two opposite sides of the shell to order each to form segments separated by the slots,
• Bending the segments with respect to a base surface of the blank along respective bending edges, and
• Bending of the shell component to form a tubular body, at the axial ends of which at least one radially inwardly projecting gas guide vane formed by an angled segment is arranged,

wherein at least one of the segments is bent at least once along another bending edge in it.

Further developments of the invention are set forth in the dependent claims, the description and the accompanying drawings.

• 1 eine Seitenansicht einer erfindungsgemäßen Mischvorrichtung,
• 2 eine perspektivische Ansicht der Mischvorrichtung von 1 mit Blickrichtung schräg von vorn auf die Gaseintrittsseite,
• 3 eine perspektivische Ansicht der Mischvorrichtung von 1 mit Blickrichtung schräg von hinten auf die Gasaustrittsseite,
• 4 eine Draufsicht auf ein Rohbauteil, aus dem die Mischvorrichtung von 1 herstellbar ist, und
• 5 eine weitere Draufsicht auf das Rohbauteil von 4 mit markierten Faltkanten.

The invention will now be described by way of example with reference to the drawings. Show it:

• 1 a side view of a mixing device according to the invention,
• 2 a perspective view of the mixing device of 1 with view obliquely from the front to the gas inlet side,
• 3 a perspective view of the mixing device of 1 with view obliquely from behind on the gas outlet side,
• 4 a plan view of a shell component, from which the mixing device of 1 is manufacturable, and
• 5 another plan view of the shell part of 4 with marked fold edges.

The in the 1 to 3 illustrated mixing device 11 comprises a tubular body 13 which has a hexagonal cross section and that of an exhaust gas flow in a main flow direction S can be flowed through. The main flow direction S runs parallel to the longitudinal axis here A of the tubular base body 13 , At the axial ends of the body 13 are respective arrangements of a plurality of evenly distributed along the pipe circumference and radially inwardly projecting gas guide vanes 15A . 15B arranged. The arrangements of gas guide vanes 15A . 15B serve to generate turbulence in the exhaust stream and to evaporate a fluid injected into the exhaust stream and form in this sense an upstream mixer stage 17A and an axially spaced downstream mixer stage 17B , Preferably, the injection of the fluid takes place both in the region of the upstream mixer stage 17A as well as in the area of the downstream mixer stage 17B ,

As in particular in 2 can be seen, the gas vanes point 15A the upstream mixer stage 17A two separate surface elements 20 . 21 on that along a first fold edge 25 angled relative to each other and are arranged one behind the other in the axial direction. In the illustrated embodiment, the first fold edge extends 25 perpendicular to the longitudinal axis A but this is not mandatory. As shown, each of the downstream surface elements extends 21 the separate surface elements 20 . 21 at least substantially parallel to the longitudinal axis A while the upstream surface element 20 the separate surface elements 20 . 21 opposite the longitudinal axis A is employed (preferably less than 20 °, with high demands in terms of evaporation performance of the device but also larger values are conceivable). Overall, the gas vanes 15A the upstream mixer stage 17A arranged turbine-like and therefore provide for the generation of a certain twist in the exhaust stream, which is smaller, however, than that through the second stage 17B generated swirl.

As in particular in 3 The gas guide vanes are also visible 15B the downstream mixer stage 17B opposite the longitudinal axis A employed and arranged like a turbine. Furthermore, the gas vanes 15B the downstream mixer stage 17B each at the downstream end portion in two juxtaposed strips 27 . 28 divided. Each one of the stripes 28 is along a second fold edge 35 opposite an upstream surface segment 30 the relevant gas guide vane 15B angled while the other strip 27 not angled, so the result is the two stripes 27 . 28 with respect to the longitudinal axis A are employed in different degrees. In the embodiment shown, the second folded edge extends 35 at least substantially at right angles to the longitudinal axis A , It could also be both stripes 27 . 28 along the second fold edge 35 opposite the upstream surface segment 30 be angled, optionally in the same or in the opposite direction. Instead of a common folding edge 35 can also be provided separate folding edges.

The along the second fold edges 35 angled stripes 28 make up - along with the stripes 27 - an additional mixer stage 17C which improves the distribution and evaporation of a fluid injected into the exhaust stream. At the free end of the along the second folding edges 35 angled stripes 28 is each a groove 37 provided, which further increases the mixing performance.

The tubular body 13 is - as shown - by circumferentially adjacent planar surface sections 39 formed, from each of which a surface piece 40 as an additional guide element is bent inward.

It is understood that additional mixer stages can be easily formed by additional folds.

In the illustrated embodiment, all existing gas guide vanes 15A . 15B formed from at least substantially planar surface areas. The surface elements 20 . 21 , the upstream surface segments 30 , the Stripes 27 . 28 and / or the inwardly bent sheet pieces 40 but could also be curved.

In the 1 to 3 shown mixing device 11 is made in one piece. In particular, the main body 13 , the gas vanes 15A . 15B as well as the inwardly bent surface pieces 40 formed by forming a one-piece sheet metal component, as described below with reference to 4 and 5 is carried out closer.

For producing the mixing device 11 becomes a flat shell component 45 as in 4 and 5 shown provided. The shell component 45 can be made of sheet steel or of a composite material such. B. a plated copper-stainless steel connection. On two opposite sides of the shell component 45 be slits 47 . 48 . 49 . 50 cut. The through the slots 47 . 48 . 49 . 50 separate areas of the shell component 45 are opposite a ground plane of the shell component 45 angled, especially along the first folding edges 25 and the second fold edges 35 , The shell component 45 then becomes the tubular body 13 ( 1 to 3 ) "Rolled up".

LIST OF REFERENCE NUMBERS

11

mixing device

13

body

15A, 15B

Gasleitschaufel

17A

upstream mixer stage

17B

downstream mixer stage

17C

additional mixer stage

20

upstream surface element

21

downstream surface element

25

first folding edge

27, 28

strip

30

upstream surface segment

35

second fold edge

37

groove

39

surface section

40

patch

45

cast-in part

47-50

slot

S

Main flow direction

A

longitudinal axis

Claims (17)

Mixing device (11) for distributing and vaporizing a fluid in an exhaust gas stream, with a particular tubular body (13), at the axial ends of each at least one radially inwardly projecting gas guide vane (15A, 15B) is arranged to an upstream and a downstream mixer stage (17A, 17B) axially spaced from each other, characterized in that at least one of the gas vanes (15B) of one of the mixer stages (17B) is provided with at least two separate surface segments (28, 30) to form a third mixer stage (17C) which are angled along a folding edge (35) relative to each other, wherein the surface segments (28, 30) which form the third mixer stage (17C) have a free end portion disposed in at least two and preferably exactly two juxtaposed and by a Slit (49) separated strips (27, 28) is divided with respect to a longitudinal axis (A) of the base body (13) below are strongly hired. Mixing device after Claim 1 , characterized in that the two separate surface segments (28, 30) in each case with respect to a longitudinal axis (A) of the base body (13) are employed, preferably at an angle of at least 20 ° and at most 60 °, and more preferably at an angle of at least 30 ° and at most 50 °. Mixing device after Claim 1 or 2 , characterized in that the two separate surface segments (28, 30) are each at least substantially planar. Mixing device according to at least one of the preceding claims, characterized in that the at least one gas guide vane (15B) forming the third mixer stage (17C) is arranged at a downstream end of the downstream mixer stage (17B). Mixing device according to at least one of the preceding claims, characterized in that an arrangement of a plurality of gas guide vanes (15B) distributed along the pipe circumference of the tubular base body (13) is provided for forming the third mixer stage (17C), wherein each of the distributed arranged gas guide vanes (15 B) has two separate and along a respective folding edge (35) relative to each other angled surface segments (28, 30). Mixing device after Claim 5 , characterized in that the distributed arranged gas guide vanes (15B) are arranged to generate a twist in the exhaust gas flow turbine-like. Mixing device according to at least one of the preceding claims, characterized in that the folding edge (25) extends at right angles or obliquely to a longitudinal axis (A) of the base body (13). Mixing device according to at least one of the preceding claims, characterized in that the third mixer stage (17C) has three separate surface segments, which are angled along two folding edges relative to each other. Mixing device after Claim 8 , characterized in that the two fold edges extend along intersecting straight lines. Mixing device according to at least one of the preceding claims, characterized in that the gas guide vane (15A, 15B) of the upstream and / or the downstream mixer stage (17A, 17B) has two separate surface elements (20, 21) along a folding edge (25) relative angled to each other and are arranged in particular in the axial direction one behind the other. Mixing device after Claim 10 , characterized in that the at least one gas guide vane (15A) of the first mixer stage (17A) relative to the longitudinal axis (A) is employed by an angle of attack of less than 20 °. Mixing device according to at least one of the preceding claims, characterized in that the base body (13) has a lateral surface, from which at least one surface piece (40) is bent out as an additional guide element, in particular to the inside. Mixing device according to at least one of the preceding claims, characterized in that the base body (13), the gas guide vanes (15A, 15B) and / or the surface segments (28, 30) are formed by forming from a one-piece sheet metal component (45). Mixing device according to at least one of the preceding claims, characterized in that the base body (13), the gas guide vanes (15A, 15B) and / or the surface segments (28, 30) made of a composite material, in particular of a plated copper-stainless steel compound is / are. Mixing device according to at least one of the preceding claims, characterized in that the base body (13) has a polygonal, in particular a hexagonal, cross-section and / or that the base body (13) by circumferentially adjacent planar surface portions (39) is formed. Mixing device according to at least one of the preceding claims, characterized in that a portion of a free end of the third mixer stage (17C) forming surface segments (28) has a groove (37). A method of manufacturing a mixing device (11) for distributing and vaporizing a fluid in an exhaust stream according to any one of the preceding claims, comprising the steps of: Providing a flat shell component (45), - slitting slots (47, 48, 49, 50) on two opposite sides of the blank (45) to form respective segments separated by the slots, Bending the segments with respect to a base surface of the blank (45) along respective bending edges, and Bending the raw component (45) to form a tubular body, at the axial ends of which at least one radially inwardly projecting gas guide vane (15A, 15B) formed by an angled segment is arranged, at least one of the segments at least once along a further bending edge (FIG. 35) is bent in itself.

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