DE102017216993B3 - mixing device - Google Patents

Abstract

The invention relates to a mixing device for arranging in a fluid line, in particular for arranging in an exhaust line of an internal combustion engine, which has at least one Fluidleitbereich (11, 21) with a plurality of about an axis (A) arranged Fluidleiteinrichtungen (12, 22) for mixing a mixing device ( 10) flowing through the fluid. The mixing device has at least two radially adjacent, coaxially arranged around the axis Fluidleitbereiche (11, 21), each with a plurality of circumferentially distributed, helically formed Fluidleiteinrichtungen (12, 22). By means of the fluid guide devices (12) of the first fluid guide region (11) and the fluid guide devices (22) of the second fluid guide region (21), the fluid overflowing the respective fluid guide device (12, 22) can be set into a twist.

Description

The invention relates to a mixing device for arranging in a fluid line with at least one Fluidleitbereich with a plurality of fluid guide means arranged around an axis for mixing a fluid flowing through the mixing device and arrangements with such a mixing device.

Such mixing devices are known. They are used to achieve a uniform distribution of the constituents in a fluid flow, in which they effect a mixing of the flowing fluid by means of flow obstacles arranged in the flow cross-section of a fluid line. If, for example, liquid additives are introduced into a gaseous fluid stream, they on the one hand support the distribution and absorption of the droplets in the fluid stream and on the other hand promote the fragmentation of larger droplets at the obstacles, whereby the resulting smaller droplets are better absorbed and distributed in the fluid stream. Especially at high temperatures, the flow obstacles of the mixing device also have high temperatures, at the surfaces of which unmixed droplets of the gaseous fluid flow carried liquid additives evaporate and then distribute in the passing fluid flow and are absorbed by this.

One application of such mixing devices are modern exhaust systems of internal combustion engines. Such exhaust systems work for exhaust gas purification with reducing agents, which are introduced into the exhaust gas stream. Arranged in an exhaust pipe mixing devices are used for uniform mixing of the components of the exhaust stream and for evaporating introduced into the exhaust stream reducing agents in order to achieve the best possible effect of a catalyst flowed through by the exhaust gas.

For this purpose is for example from the DE 10 2014 223 382 A1 a device for the aftertreatment of the exhaust gases of an internal combustion engine is known, which has a mixing device for twisting the exhaust gas flow around a swirl center axis.

The mixer is formed by nine integrally formed with the tubular element and pointing radially inward Fluidleitelemente, which are arranged distributed uniformly over the circumference of the tubular element. The fluid guide elements are wing-like. In this case, the side edges of a fluid-conducting element have a twisted course, as a result of which a swirl is generated in the exhaust-gas flow which is intended to cause mixing of the reducing agent with the exhaust-gas flow. However, the proposed arrangement of the fluid guide elements produces a rather uniform swirl flow, which does not lead to a satisfactory mixing of the exhaust gas flow. Furthermore, the proposed design in the center of a flow-through, which, for example, can be flowed through by larger droplets of an additive, without any division and evaporation takes place in the mixing device.

From the German patent application DE 10 2012 224 198 Also, a mixing device for distributing and vaporizing an additive in a gas stream is known. The mixing device has a first mixer impressing a first swirl component and a second mixer impressing the gas flow on a second swirl component, wherein the first and second mixers are arranged one behind the other in the flow direction of the gas flow, and the first and the second swirl components are in opposite directions. A disadvantage of the proposed mixer design is the high flow resistance, which is connected to the flow through two successive mixing devices.

From the US patent application US 2007/0 205 523 A1 , from the German patent DE 10 2015 121 708 B3 and the publication of the European patent application EP 2 596 854 A1 Various mixers are known, which have two radially adjacent, arranged coaxially about an axis Fluidleitbereiche each having a plurality of circumferentially distributed Fluidleiteinrichtungen, wherein by means of Fluidleiteinrichtungen the first Fluidleitbereichs and the Fluidleiteinrichtungen the second Fluidleitbereichs the fluid overflowing the respective Fluidleiteinrichtung is set into a twist, wherein the pressure which can be impressed by the fluid guide devices of the first fluid guide region is opposite to that which can be impressed by the fluid guide devices of the second fluid guide region.

On this basis, the invention has the object to propose an improved mixing device. This is achieved according to the invention by the teaching of claim 1. Advantageous embodiments of the invention are the subject of the dependent claims.

To solve the problem, a mixing device for arranging in a fluid line is proposed, in particular for arranging in an exhaust pipe of an internal combustion engine. The mixing device has at least one fluid guide region with a plurality of fluid guide devices arranged around an axis for mixing a fluid flowing through the mixing device. Coaxially about the axis of the mixing device are at least arranged two radially adjacent Fluidleitbereiche, each with a plurality of circumferentially distributed, helically formed Fluidleiteinrichtungen. By means of the fluid guide devices of the first fluid guide region and by means of the fluid guide devices of the second fluid guide region, the fluid flowing over the respective fluid guide device can be set in a twist, wherein the twist which can be impressed by the fluid guide devices of the first fluid guide region is opposite to the twist which can be impressed by the fluid guide devices of the second fluid guide region. At least the fluid-conducting devices of the second fluid-conducting region are individual cup-shaped wings produced from sheet-metal sections, and the fluid-conducting devices of the second fluid-conducting region are welded to their radially inner circumference on the radially outer circumference of the fluid-conducting devices of the first fluid-conducting region.

The mixing device has at least two Fluidleitbereiche, which are arranged radially adjacent and coaxial about the axis of the mixing device. The at least two Fluidleitbereiche are thus arranged substantially in an axial plane of the fluid line. In this proposed design, a fluid guide region is disposed radially inwardly or outwardly of at least one second fluid guide region so that a portion of the fluid flow passes through a fluid guide region and another portion of the fluid flow through another fluid guide region. In the case of a fluid line with a circular cross-section, the fluid guide regions are, for example, annular.

In the Fluidleitbereichen a plurality of circumferentially distributed, helically formed Fluidleiteinrichtungen are arranged in each case. In particular, the fluid guide devices are distributed uniformly over the circumference, so that the guidance of the fluid, by means of which an angular momentum (swirl) is impressed on the fluid flow, and thus the thorough mixing of the fluid flow, takes place as uniformly as possible over the cross section. The number and configuration of the Fluidleiteinrichtungen results in particular from the conditions of use of the mixing device such as the flow rate and flow rate, the desired angular momentum or the desired mixing of the fluid flowing through or from the design of Fluidleitbereichs. In order to impart an angular momentum to the fluid during the overflow of the fluid-conducting devices, the fluid-conducting devices are helically configured, that is to say that the surfaces of the fluid-conducting devices overflowed by the fluid flow extend helically in the circumferential direction of the mixing device and thus inclined around the central axis of the mixing device.

Consequently, the fluid flowing through the mixing device is deflected along the fluid line starting from the previous axial flow and caused to spin when the helically configured or arranged surfaces of the fluid guide devices overflow. The design of the fluid-conducting devices of the first fluid-conducting region differs from the design of the fluid-conducting devices of the second fluid-conducting region in that the swirl which can be impressed by the fluid-conducting devices of the first fluid-conducting region is in opposite direction to the swirl which can be impressed by the fluid-conducting devices of the second fluid-conducting region. In order to achieve this, in particular the helically shaped surfaces of the fluid guiding device of the at least two fluid guide regions are formed in opposite directions, in particular the surfaces of the fluid guide devices have an opposite inclination about the central axis of the mixing device or the fluid line.

The proposed design has over the known prior art has the advantage that is offset by the at least two coaxially arranged Fluidleitbereiche the fluid flow in each of these areas in opposite directions to each other in a twist, so that forms an acted in particular with a double or multiple spin flow , The flow areas acted upon by different rotational pulses are superimposed after flowing through the mixing device, whereby a further mixing and distribution of the constituents of the fluid flow and an improved absorption of, for example, vaporized additives in a gaseous fluid flow takes place.

In addition, results from the double or multiple twist uniform flow distribution over the cross section of the fluid line, the angular momentum loses in the further flow through the fluid line again. Thus, the proposed mixing device achieves a largely homogeneous mixing of the fluid flowing through it, wherein the flow, in particular before reaching a downstream substrate such as a catalyst or a filter again has a substantially uniform flow over the cross section substantially along the axial direction of the fluid line.

The Fluidleiteinrichtungen the second Fluidleitbereichs are formed by sheet metal sections. By means of a forming process, such as thermoforming, it is possible to produce particularly aerodynamically designed components which, for example, have no edges or the like which impede the flow of fluid. So it is possible, the fluid guiding devices as a single To produce formed parts, which are joined together by means of a welding process to form a Fluidleitbereich.

In one embodiment of the mixing device, each Fluidleiteinrichtung upstream of an inclined to the cross section of the fluid line Anströmbereich through which the fluid flow is deflected relative to the flow direction along the axis of the fluid line so that the fluid flow after flowing over the Anströmbereichs the Fluidleiteinrichtung arranged a helical about the axis Has twist. The inflow region is thus arranged on the fluid-conducting device such that it is first reached by the fluid flow and is designed such that it guides the fluid flow to the fluid-conducting device such that it is impressed with a helically arranged swirl around the axis when the fluid-conducting device flows over. In addition, the inflow region is also the region which is impinged by particles or droplets guided as an obstacle by the fluid flow and on which, for example, particles or droplets are broken up by an impact and / or droplets evaporate at high temperatures.

In one embodiment of this mixing device, each Fluidleiteinrichtung downstream of an inclined to the cross section of the fluid conduit discharge area, which is arranged so that it flows over by a flowing fluid through the mixing device after overflow of the Anströmbereichs one in the direction of the impressed swirl previously arranged fluid guide the same Fluidleitbereichs is. In this design, the fluid flow is guided after the overflow of Anströmbereichs a Fluidleiteinrichtung on the Anströmbereich another following in the direction of the pronounced angular momentum fluid guide. This design leads to a stable flow of the fluid provided with a swirl after flowing through the fluid-conducting region, which decreases again in the further course of the flow along the fluid line, so that, in particular, a uniform longitudinal flow is again formed in the fluid line.

In one embodiment of the mixing device, the inclination of the inflow region and / or the inclination of the outflow region relative to the cross section of the fluid line and thus the passage cross section of the mixer can be adjusted. By adjusting the inclination or the angle of inclination of the inflow region or the outflow region relative to the cross section of the fluid line, the volume flow of the fluid flowing through the mixing device can be influenced, whereby the fluid back pressure of the fluid flowing in the fluid line can be reduced or even increased.

In one embodiment of the mixing device, at least one fluid guide device has at least one opening through which fluid can flow in the axial direction of the fluid line. The part of a fluid flow, which flows through such an opening through which an axial flow can flow, is not subject to the application of an angular momentum and thus remains free of twisting after the mixing device. Such a flow region is also superimposed after passing through the mixing device with the flow region acted upon by an angular momentum, whereby a mixing and distribution of the components of the fluid flow and an improved absorption of, for example, vaporized additives in a gas stream. Furthermore, the volume flow of the fluid flowing through the mixing device can also be influenced by the size and number of openings through which the mixing device can flow, as a result of which the fluid back pressure of the fluid flowing in the fluid line can be reduced or also increased.

In one embodiment of the mixing device, the fluid-conducting devices of the first fluid-conducting region are also sheet metal sections produced by deformation. By means of a forming process, such as thermoforming, it is possible to produce particularly aerodynamically designed components which, for example, have no edges or the like which impede the flow of fluid. Thus, it is also possible to produce the Fluidleiteinrichtungen as individual Umformteile, which are connected to each other for example by means of a cohesive method, such as a soldering or welding process to form a Fluidleitbereich. In the same way, it is advantageously also possible to connect a plurality of such fluid-conducting regions to a mixing device.

In one embodiment of the mixing device, the fluid guiding devices arranged on the circumference of the mixing device have connecting devices arranged radially on the outside for connecting the mixing device to the fluid line. Such connecting devices, as they are easy to produce, for example, in mixing equipment produced by forming, allow a simple arrangement of a mixing device in a fluid line, for example, they are used for welding the mixing device with the internal conversion of the fluid line.

In a further aspect, the invention proposes an arrangement for mixing a fluid flowing in a fluid line, wherein a mixing device configured as described above is arranged in the fluid line. After flowing through such an arrangement has a fluid a homogeneous distribution of its components over the cross section of the flow.

In a further aspect, the invention proposes an arrangement for introducing an additive into a fluid flowing in a fluid conduit. Such an arrangement has a mixing device of the type described above and a feed device for the additive in the fluid line. An introduction device can be, for example, a nozzle arranged in the fluid line, such as an injection nozzle or another dispensing device for a substance, which is arranged in front of the mixer in the flow direction, so that an additive introduced into the fluid line by means of the introduction device flows through the mixing device and over the subsequent distribution is distributed evenly in the fluid in particular by the double twist, so that for a subsequent process step, the fluid is present with a homogeneous distribution as possible, in particular of the introduced by the introduction additive.

• 1 eine beispielhafte erfindungsgemäße Mischeinrichtung aus strömungsaufwärtiger Sicht des Anströmbereichs der Mischeinrichtung;
• 2 eine Anordnung zum Einbringen und Mischen eines Zusatzstoffes in ein in einer Fluidleitung strömenden Fluid;
• 3 eine dreidimensionale Darstellung der beispielhaften erfindungsgemäßen Mischeinrichtung aus 1;
• 4 eine weitere dreidimensionale Darstellung der beispielhaften erfindungsgemäßen Mischeinrichtung aus 1 aus einer anderen Perspektive;
• 5 eine weitere dreidimensionale Darstellung der beispielhaften erfindungsgemäßen Mischeinrichtung aus 1 aus einer dritten Perspektive; und
• 6 die beispielhafte erfindungsgemäße Mischeinrichtung in der Perspektive aus 5 mit beispielhaft eingezeichneten Strömungsverlauf.

Other features, advantages and applications of the invention will become apparent from the following description taken in conjunction with the figure. It shows

• 1 an exemplary mixing device according to the invention from the upstream view of the Anströmbereichs the mixing device;
• 2 an arrangement for introducing and mixing an additive into a fluid flowing in a fluid conduit;
• 3 a three-dimensional representation of the exemplary mixing device according to the invention from 1 ;
• 4 a further three-dimensional representation of the exemplary mixing device according to the invention from 1 from another perspective;
• 5 a further three-dimensional representation of the exemplary mixing device according to the invention from 1 from a third perspective; and
• 6 the exemplary mixing device according to the invention in perspective 5 with exemplified flow pattern.

1 shows an exemplary mixing device according to the invention 10 from an upstream view of the Anströmbereichs the mixing device. The exemplary mixing device 10 has two Fluidleitbereiche 11 and 21 on, which are arranged coaxially about the axis. The two Fluidleitbereiche 11 . 21 are arranged radially adjacent and each have four circumferentially distributed, helically formed Fluidleiteinrichtungen 12 . 22 on. The Fluidleiteinrichtungen 12 of the first Fluidleitbereichs 11 are formed so that an overflowing fluid is acted upon with an anti-clockwise angular momentum, and the Fluidleiteinrichtungen 22 the second Fluidleitbereichs 21 are designed so that a fluid flowing over this is acted upon by a clockwise angular momentum. The deflection of the fluid flow, by means of which the fluid flow is put into a spin, takes place at the inflow region 13 the Fluidleiteinrichtungen 12 or at the inflow area 23 the Fluidleiteinrichtungen 22 ,

The upstream flow areas 13 and 23 are each helically formed inclined to the cross section of the fluid conduit to guide the fluid flowing over this and to apply an angular momentum. The exemplary mixing device according to the invention 10 also has openings through which fluid can flow in the axial direction of the mixing device 8th which serves to reduce the dynamic pressure resulting from the mixing device in the fluid and also a further, namely in particular at a higher speed in the axial direction of the fluid line directed flow component into the fluid behind the mixing device 10 contributes to further increase the degree of mixing in the fluid.

2 shows an arrangement 50 for introducing an additive into a fluid conduit 30 flowing fluid. In the schematically illustrated fluid line 30 is the exemplary mixer 10 out 1 arranged and shown in a side view. The mixing device 10 is traversed by a fluid which, prior to reaching the mixing device 10 one through the flow arrows 31 having shown uniform flow. Upstream of the mixer 10 is a nozzle 51 arranged, by means of which an additive 52 in the fluid line 30 is introduced. The largely inhomogeneous mixture of fluid and additive 52 then flows through the mixer 10 , As by the exemplary flow arrows 32 which exemplary flow components in the fluid after flowing through the mixing device 10 represent, has the fluid depending on the area of the mixing device through which flows 10 different angular momentum. In particular, the proposed design of the mixing device leads 10 with two Fluidleitbereichen 11 . 21 which impose opposing angular momentum on the fluid flowing through it, leading to a formation of a double twist in the fluid flow, which enables a uniform mixing of the flowing fluid.

In the in 2 shown side view of the exemplary mixing device 10 are the helical around the axis A trained outflow areas 14 . 24 the Fluidleiteinrichtungen 12 . 22 the Fluidleitbereiche 11 . 21 easily recognizable, which in the respective inflow area 13 . 23 continue impressed swirl of the fluid flow and reinforce. Furthermore, in 2 also the inclination α a discharge area 24 opposite the cross section of the fluid line 30 located.

A through the introduction device 51 introduced in particular liquid additive 52 initially distributed roughly within the fluid. Smaller droplets are quickly absorbed in the fluid, whereas larger droplets can remain unified, and thus do not mix with the fluid. When approaching the mixing device 10 For example, larger droplets encounter an inflow area 13 . 23 and are there, for example, by the increased flow or when hitting the Anströmbereich divided. For example, a liquid additive 52 introduced into a gaseous fluid having a high temperature, so also has the mixing device 10 a high temperature, which is an evaporation of the additive 52 at the mixing device 10 promotes. The gaseous additive 52 is then absorbed by the passing fluid.

In the 2 shown exemplary arrangement for introducing an additive into a in a fluid line 30 flowing fluid is particularly suitable for use in an exhaust pipe of an internal combustion engine. In the exhaust gas flowing in an exhaust gas to improve the effect of exhaust aftertreatment as an additive reducing agent such as urea introduced to improve the effect of a subsequently traversed by the exhaust gas catalyst, in particular a selective reduction catalyst (SCR). The efficiency of such catalysts also depends on the availability of the reducing agent in the exhaust gas, for which the most uniform possible distribution of this additive in the exhaust gas is required.

3 shows a three-dimensional representation of the exemplary mixing device 10 , in a downstream perspective. In this perspective, it can be clearly seen that the fluid guiding devices 22 are single made of sheet metal sections forming technology wings. The Fluidleiteinrichtungen 22 are cup-shaped, and have a particularly aerodynamically favorable shape. Good to see are the large passage cross sections 33 . 34 between the inflow area 13 . 23 a fluid guide 12 . 22 and the outflow area 14 . 24 a fluid guide 12 . 22 , Also the Fluidleiteinrichtungen 12 the exemplary mixing device 10 are individual formed by manufacturing wings, which are welded together. The Fluidleiteinrichtungen 22 are on the radially outer periphery of the Fluidleiteinrichtungen 12 welded to the mixing device 10 manufacture. Further, on the outer circumference of the Fluidleiteinrichtungen 22 connecting devices 25 arranged, which for connecting the mixing device 10 with the fluid line 30 are usable.

4 Figure 3 shows another three-dimensional representation of the exemplary mixing device 1 in an upstream perspective. In particular, in this perspective, there is the opposite helical slope of the fluid directors 12 . 22 around the central axis A with the respective inflow 13 . 23 and outflow areas 14 . 24 as well as the passage cross section 34 between two fluid guiding devices 22 recognizable.

5 Figure 3 shows another three-dimensional representation of the exemplary mixing device 1 in an upstream perspective, which is only slightly opposite the front view 1 is inclined. From this representation it follows that the louvers 12 . 22 a flow through the mixing device 10 in the axial direction apart from the intended flow through the openings 8th blocked and still has large opening cross-section to keep the fluid back pressure low.

6 shows the exemplary mixing device according to the invention 10 in perspective 5 with exemplified flow pattern. By way of illustration, the flowlines are plotted from a more top-down perspective. Here are, similar to in 2 from the flow through the mixing device 10 resulting different flow directions of individual fluid areas can be seen, which serve in particular to form a double twist uniform mixing of the fluid.

LIST OF REFERENCE NUMBERS

8th

openings

10

mixing device

11

Fluidleitbereich

12

fluid guide

13

inflow

14

outflow region

21

Fluidleitbereich

22

fluid guide

23

inflow

24

outflow region

25

connecting device

30

fluid line

31

flow arrows

32

flow arrows

33

Passage section

34

Passage section

50

Arrangement for introducing an additive into a flowing fluid

51

introducing device

52

additive

A

axis

Claims (9)

Mixing device for arranging in a fluid line, in particular for arranging in an exhaust line of an internal combustion engine, which has at least one Fluidleitbereich (11, 21) with a plurality of arranged around an axis Fluidleiteinrichtungen (12, 22) for mixing a mixing device (10) flowing through the fluid at least two radially adjacent, coaxially about the axis (A) arranged Fluidleitbereiche (11, 21), each with a plurality of circumferentially distributed, helically formed Fluidleiteinrichtungen (12, 22) are arranged, wherein by means of Fluidleiteinrichtungen (12) of the first Fluidleitbereichs (11) and the Fluidleiteinrichtungen (22) of the second Fluidleitbereichs (21) that the respective Fluidleiteinrichtung (12, 22) overflowing fluid is set into a twist, wherein the by the Fluidleiteinrichtungen (12) of the first Fluidleitbereichs (11) can be impressed in the opposite direction to that by the Fluidleiteinrichtungen (22) of the second Fluidleitbere Is (21) can be impressed swirl, characterized in that at least the Fluidleiteinrichtungen (22) of the second Fluidleitbereichs (21) are individual cup-shaped, formed from sheet metal sections forming wings, and the Fluidleiteinrichtungen (22) of the second Fluidleitbereichs (21) at the radial inner circumference at the radially outer periphery of the Fluidleiteinrichtungen (12) of the first Fluidleitbereichs (11) are welded. Mixing device after Claim 1 , characterized in that each Fluidleiteinrichtung (12, 22) upstream of the cross-section of the fluid line (30) inclined Anströmbereich (13, 23) through which the fluid flow relative to its flow along the axis (A) of the fluid line (30) deflected so is that the fluid flow after the overflow of the Anströmbereichs (13, 23) of the Fluidleiteinrichtung (12, 22) has a helically arranged about the axis (A) swirl. Mixing device after Claim 2 , characterized in that each Fluidleiteinrichtung (12, 22) downstream of the cross-section of the fluid line (30) inclined outflow region (14, 24) which is arranged so that this from a by the mixing device (10) flowing fluid after the overflow the inflow region (13, 23) of a fluid guide device (12, 22) of the same fluid-conducting region (11, 21) arranged in advance in the direction of the impressed swirl can be overflowed. Mixing device according to one of the preceding claims, characterized in that by the inclination of the Anströmbereichs (13, 23) and / or the inclination of the outflow region (14, 24) relative to the cross section of the fluid line (30) of the passage cross section (33, 34) of the mixing device (10) is adjustable. Mixing device according to one of the preceding claims, characterized in that at least one fluid guide device (12, 22) has at least one opening (8) through which fluid can flow in the axial direction of the fluid line (30). Mixing device according to one of the preceding claims, characterized in that the fluid-conducting devices (12) of the first fluid-conducting region (11) are sheet-metal sections produced by deformation. Mixing device according to one of the preceding claims, characterized in that on the circumference of the mixing device (10) arranged Fluidleiteinrichtungen (22) radially outwardly arranged connecting means (25) for connecting the mixing device (10) with the fluid line (30). Arrangement for mixing a fluid flowing in a fluid line, characterized in that in the fluid line (30) a mixing device (10) according to one of Claims 1 to 7 is arranged. Arrangement for introducing an additive into a fluid flowing in a fluid line, characterized by a mixing device (10) according to one of Claims 1 to 7 and an introduction device (51) for the additive (52) into the fluid line (30).

Images