DE112013007793B4 - DEVICE FOR MIXING AN EXHAUST GAS STREAM - Google Patents

Abstract

Mixer (600, 600a, 700) for mixing an exhaust gas stream in an exhaust pipe, the mixer (600, 600a, 700) comprising: a tubular housing (612, 612a, 720) with circumferentially spaced slots (616, 618, 646, 648, 654, 656, 688, 690, 726a-i) extending through the housing (612, 612a, 720) for a predetermined axial length, the tubular housing (612, 612a) having radially inwardly extending depressions (650 , 652, 724a-i), which are arranged adjacent to the slots (654, 656), a first mixing element (602, 604a) having a central portion that connects a first peripheral portion (624) to a spaced-apart second peripheral portion (626). , wherein the first peripheral portion (624) is attached to one of the recesses (650, 652, 724a-i) associated with one of the slots (654, 656), wherein the second peripheral portion (626) is attached to another of the recesses (650 , 652, 724a-b) associated with another one of the slots (654, 656), and a second mixing element (604) having a central portion interconnecting third and fourth spaced peripheral portions (642, 644), the third and fourth peripheral sections (642, 644) are attached to other recesses associated with other of the slots (616, 618, 646, 648, 688, 690, 726a-i), the second mixing element (604) being separated from the first mixing element ( 602, 604a) is spaced apart.

Description

BACKGROUND OF THE INVENTION

1. Field of invention

The invention relates to a mixer.

2. State of the art

According to the most closely related art, several single-stage mixers are known.

In the DE 10 2006 024 778 B3 A mixer is described in which a wall structure is provided for flow guide surfaces, which essentially fills the profile of a housing and thereby causes a relatively high dynamic pressure loss. The wall structure consists of several layers of corrugated strip material that are aligned parallel to the direction of flow. The individual layers each extend transversely to the direction of flow and are stacked on top of each other aligned transversely to the direction of flow. Here, the strip material in the individual layers is stacked on top of one another in such a way that several cells are formed between the strip material of adjacent layers, each of which can be flowed through in the direction of flow.

In addition to a round corrugation, the corrugations of the strip material can also be rectangular or trapezoidal, so that rectangular, hexagonal or honeycomb profiles can be obtained for the individual cells. The strip material forms a support on which flow guide surfaces are formed in pairs as mixing lamellae. For this purpose, the carrier alternately has a region with a mixing lamella and a region connected thereto and having no mixing lamellas, so that a mixing lamella extends into each cell.

In the DE 20 2006 017 848 U1 a device for mixing exhaust gases is described, wherein a fin unit, which consists of fins arranged directly one after the other, causes the exhaust gas to be mixed. The lamella units are arranged next to each other transversely to the direction of flow and one behind the other in the direction of flow. The slats are directly connected to one another without a support and are arranged mirror-symmetrically with respect to a central plane.

10 2005 059 971 A1 discloses a device for mixing a fluid with a large gas flow (basic flow) flowing in a gas channel, in particular for introducing a reducing agent into a flue gas containing nitrogen oxides, with at least one nozzle lance with at least one nozzle for supplying the fluid , the axis of which forms an angle with the flow direction of the gas flow, and at least one flat mixer element assigned at a distance to the nozzle, which forms an angle with the flow direction of the gas flow, flow vortices forming on the mixer element and at least part of the fluid getting into these flow vortices .

In the DE 10 2006 043 225 A1 describes an exhaust system for an internal combustion engine with an exhaust pipe carrying the exhaust gas and an injection device for injecting a liquid into the exhaust pipe. Downstream of the injection device, an evaporation unit is provided in the exhaust line, which has at least one tubular plate body extending in a longitudinal direction of the exhaust line and effects improved evaporation of the injected liquid. Furthermore, a spring-type clamping device is provided, which fixes the evaporation device in the exhaust pipe or clamps it against the exhaust pipe.

As the technology most closely related to the prior art is in the DE 10 2005 052 064 A1 an exhaust system with an injection device for a reducing agent is described, in which a plate body is arranged downstream of the injection device, which has at least one wall which extends in the longitudinal direction of the exhaust line and is exposed to the exhaust gas flow on both sides. The reducing agent is at least partially sprayed onto the wall, resulting in a conversion of the liquid reducing agent into a vapor or gaseous state.

DE 10 2008 028 627 A1 discloses a static mixer for an exhaust pipe of an exhaust system of an internal combustion engine that carries exhaust gas in a flow direction. The mixer has several mixing elements for the exhaust gas arranged next to one another transversely to the flow direction. Several mixing blades are arranged on each mixing element and each mixing blade has a front edge area, a rear edge area and two side edge areas in relation to the flow direction. Each mixing element has an aligned support on which the mixing blades are arranged over their rear edge region Rh and are positioned relative to the support. Each carrier is attached to the exhaust pipe via its two end regions, so that at least three mixing elements can be arranged next to each other transversely to the direction of flow with a distance of at least 5 mm from one another and all mixing blades with all lateral ones Edge areas and with the front edge area spaced from the exhaust pipe 40 are arranged.

US 2011 / 0 258 983 A discloses a mixer for an exhaust aftertreatment system, such as a diesel engine exhaust aftertreatment system, is disclosed. The mixer includes a body portion configured to be disposed in an exhaust conduit upstream of an exhaust aftertreatment device, and a blade portion disposed on the body portion and reversibly movable between an extended position and a retracted position, the blade portion in the in the extended position provides an extended resistance to an exhaust gas flow and in the retracted position provides a retracted resistance and the extended resistance is greater than the retracted resistance. The mixer preferably comprises a two-way shape memory alloy, in particular a high-temperature and oxidation-resistant shape memory alloy. An exhaust aftertreatment system using the mixer and a method of using it are also disclosed.

BRIEF DESCRIPTION OF THE INVENTION

It is the object of the invention to provide a device with which the degree of mixing between the exhaust gas and the fluid is increased depending on the shape of the exhaust pipe.

1. a) der Abgasstrom wird im Bereich der Einspritzvorrichtung in einer sich parallel zur Abgasleitung erstreckenden Strömungsrichtung in der Abgasleitung geführt,
2. b) das Fluid wird bezüglich einer mittigen Einspritzrichtung, die sich unter einem Winkel se zur Strömungsrichtung erstreckt, direkt auf ein in der Abgasleitung angeordnetes Ablenkelement gespritzt,
3. c) mit Hilfe mindestens eines Blechteils, das auf dem Ablenkelement angeordnet und bezüglich der Strömungsrichtung mindestens teilweise unter einem Winkel sv angestellt ist, wird der Abgasstrom von seiner Strömungsrichtung teilweise in eine mittige Verteilrichtung abgelenkt,
4. d) das Fluid wird vor und nach dem Auftreffen auf das Ablenkelement durch den abgelenkten Teil des Abgasstroms mindestens teilweise in die Verteilrichtung transportiert und durch das angestellte Blechteil in die Verteilrichtung abgelenkt. Hierbei ist es wesentlich, dass der Abgasstrom durch das Blechteil vor dem Mischer in die Verteilrichtung abgelenkt wird, die wesentlich von der Strömungsrichtung abweicht. Der Winkel se der Richtung, in die das Fluid eingespritzt werden kann, kann hierbei zwischen 270° und 360° variieren.

This task is solved by a mixer according to claim 1.
A method for mixing an exhaust gas stream with a fluid in an exhaust pipe of an exhaust system is also described, in which the fluid is injected into the exhaust pipe by an injection device, characterized by the following method steps:

1. a) the exhaust gas flow is guided in the area of the injection device in a flow direction that extends parallel to the exhaust line in the exhaust line,
2. b) the fluid is sprayed directly onto a deflection element arranged in the exhaust pipe with respect to a central injection direction which extends at an angle se to the flow direction,
3. c) with the help of at least one sheet metal part, which is arranged on the deflection element and is at least partially set at an angle sv with respect to the flow direction, the exhaust gas stream is partially deflected from its flow direction into a central distribution direction,
4. d) the fluid is at least partially transported in the distribution direction by the deflected part of the exhaust gas flow before and after hitting the deflection element and deflected in the distribution direction by the sheet metal part. It is essential here that the exhaust gas flow is deflected through the sheet metal part in front of the mixer in the distribution direction, which deviates significantly from the flow direction. The angle se of the direction in which the fluid can be injected can vary between 270° and 360°.

As a result, the fluid injected on one side is transported towards the center and over the entire profile of the exhaust pipe, and therefore hits the mixer over the entire profile of the mixer and can then be mixed with the exhaust gas stream. Even if, for reasons of installation space, the exhaust pipe is not straight but curved, it is advantageous if the direction of movement of the fluid can be influenced by the deflection element with respect to the course of the exhaust pipe.

In addition, it is provided that the fluid at least partially impinges on a correction plate, which is arranged in front of the sheet metal part with respect to the injection direction, and at least partially undergoes a deflection in the flow direction and is then deflected in several mixing directions by a static mixer with at least one mixing element and thus is further mixed. The correction plates are arranged above the sheet metal part essentially parallel to the sheet metal part and distributed on the side of the sheet metal part from which the fluid is injected. The distribution of the fluid in front of the mixer can be improved if further portions of the fluid flow are deflected from the injection direction into the flow direction by the correction plate before they reach the sheet metal part.

The sheet metal part is advantageously adjusted by means of several slats which are provided on the sheet metal part and extend at the same or different angles sv, the angle sv being between 0° and 85°. Because the slats are turned on, the sheet metal part itself can be arranged parallel to the direction of flow, so that only the slats provide the necessary deflection of the exhaust gas flow and thus the fluid.

In addition, it is advantageous if the correction plate has a plurality of drill holes which extend in a drilling direction, the drilling direction extending at an angle bs between 45° and 135° with respect to the flow direction. As a result, some of the fluid may be further distributed across the profile of the mixer by one or more correction plates. The fluid can therefore partially continues to flow into the injection device and is partially deflected by the correction plates. The accumulated part of the flow is further deflected and transported along the flow direction, while the non-accumulated part of the flow passing through the wells reaches the next correction plate in the injection direction or the sheet metal part.

The correction plate is arranged parallel to the flow direction and has a plurality of correction slats which are set at an angle sk with respect to the flow direction, the angle sk being between 95° and 265°. The correction lamellae are punched out of the correction plate so that the fluid that is not accumulated can flow through the correction plate through the openings formed by the punching. At the same time, the fluid is stabilized by the correction slats, so that, in contrast to the flow conditions described above, the fluid is deflected more slowly in the flow direction by the exhaust gas flow.

A plurality of mixing lamellae are formed on the mixing element, which are set at an angle ms with respect to the flow direction and at an angle mv with respect to the distribution direction, the angle ms being a maximum of 70° and the angle mv being greater than 1°. For the mixing process, it is advantageous if the fluid is further deflected by the mixing lamellae and is no longer guided in the same direction, which is determined by the lamella or the correction lamella.

For this method, a deflection element is advantageous, which is intended to be arranged in an exhaust pipe of an exhaust system that carries an exhaust gas stream and to deflect a fluid that is injected into the exhaust system by an injector, the deflection element being in front of one in the direction of flow static mixer can be arranged with at least one mixing element and has at least one sheet metal part which can be arranged in the exhaust gas flow, the sheet metal part being at least partially positioned at an angle sv in a distribution direction with respect to the flow direction, whereby the exhaust gas flow with the fluid is at least partially separated from the Flow direction is deflected into the distribution direction. A slat positioned at an angle sv is formed on the sheet metal part. The sheet metal part is arranged directly in front of the mixer in the flow direction in order to obtain a symmetrical distribution of the fluid, which has already partially converted into a gaseous state, over the profile of the exhaust pipe and thus over the entire mixer profile. The smaller the gaseous portion, the greater the effect of the deflection element on the mixing process by the mixer. On at least one part of the sheet metal part, a lamella is positioned at an angle sv in a distribution direction with respect to the flow direction, so that the exhaust gas flow with the fluid is at least partially deflected from the flow direction into the distribution direction. The influence of the sheet metal part arranged parallel to the flow direction itself on the deflection can be neglected.

Several slats extending at the angle sv are formed on the sheet metal part. With several slats, the fluid is deflected in such a way that it is distributed over the profile of the exhaust pipe. With several slats arranged one behind the other in the flow direction, the deflection of a flow element is greater because the deflection in the flow direction realized by the slats is partially accumulative.

The deflection element can be arranged in an exhaust pipe in such a way that the fluid impinges on the deflection element to a large extent. As a result, the speed of the fluid is initially reduced by the deflection element, so that the direction of flow can be changed more easily.

Depending on the exhaust gas mass flow and the exhaust gas temperature, the penetration depth of the fluid into the exhaust pipe and the impact area of the fluid on the deflection element change.

The deflection element has one or more correction plates which are arranged parallel to the flow direction or parallel to the sheet metal part. The correction plates slow down the fluid and enable early deflection of the fluid through the exhaust gas flow. The correction plates can have different lengths or can be constructed with equal lengths.

The correction plate has one or more correction lamellae which are set at an angle sk between 95° and 265°, and several openings which are formed transversely to the flow direction through the correction lamellae, and/or several drill holes which extend in a drilling direction, wherein the drilling direction extends at an angle bs between 45° and 135° with respect to the flow direction. Alternatively, a plurality of boreholes are provided which extend in a drilling direction, the drilling direction extending at an angle bs between 45° and 135° with respect to the flow direction. As a result, some of the fluid can flow through an opening or borehole directly in the fluid injection direction without being slowed down. The correction plates achieve flow correction and stabilization.

The sheet metal part protrudes above all correction plates in the direction opposite to the flow direction, and the sheet metal part is arranged behind the last correction plate with respect to the central injection direction. Due to the fact that the sheet metal part is arranged immediately adjacent to the wall of the exhaust pipe opposite the injection point, the sheet metal part can influence the total amount of injected fluid.

The deflection element is designed to be mirror-symmetrical with respect to a central plane which is arranged at right angles to the direction of flow, or the slats and/or the correction slats are arranged to be mirror-symmetrical with respect to the central plane. As a result of this symmetry, the central flow area in the exhaust pipe, into which the fluid is also injected, can be influenced to a much greater extent since the central mixing elements or flow elements have the same orientation.

A multi-stage distributor is also advantageous, which consists of a deflection deflection element as described above and a static mixer which is attached to the deflection element or arranged indirectly behind the deflection element and has at least one mixing element, the mixing element having at least one carrier for mixing lamellae or a flow element having. The combination of the deflection element and the mixer enables a highly effective mixing process.

The sheet metal part or the correction plate is arranged on the carrier or on the flow element parallel or diagonal to the flow direction. As a result, the mixer and the deflection element are at least partially or completely formed as a single part and from the same material.

The mixing fins or the flow elements are positioned at an angle ms of up to 70° with respect to the flow direction and at an angle mv of more than 1° with respect to the distribution direction.

The mixing element is designed to be mirror-symmetrical with respect to the central plane, which is arranged at right angles to the flow direction, or the mixing lamellas and/or the supports are arranged to be mirror-symmetrical with respect to the central plane.

Depending on the application, it could be advantageous if the mixing element is designed point-symmetrically with respect to the flow direction, or if the mixing lamellas and/or the supports are arranged point-symmetrically with respect to the flow direction. Due to this arrangement, counter-rotating vortices are generated behind the mixer in the exhaust pipe.

For assembly or retrofitting, it could be advantageous if a housing is additionally provided which extends parallel to the exhaust pipe and parallel to the flow direction of the exhaust gas, on which the carrier or the flow elements are arranged, wherein the housing can be arranged on or in the exhaust pipe. As a result, the mixing elements or flow elements of the mixer can be pre-assembled in the housing before being inserted into the exhaust pipe.

The static mixer advantageously has a plurality of mixing elements for the exhaust gas, which are arranged next to one another transversely to the flow direction, each mixing element having a plurality of mixing fins and each mixing fin having a rear boundary surface and two side boundary surfaces with respect to the flow direction. Each mixing element has a support aligned parallel to the flow direction, on which the mixing lamellae are arranged across their rear interfaces and positioned relative to the support. Each carrier has two end surfaces via which the respective carrier is attached to the exhaust pipe. At least three mixing elements are provided, the supports of which are arranged adjacent to each other at a distance of at least 5 mm in the area between the end surfaces transverse to the direction of flow. All mixing fins are arranged with all side interfaces and the front interface at a distance from the exhaust pipe. Preferably, the adjacent supports have a distance between 5 mm and 100 mm, preferably between 12 mm and 15.5 mm. As a result, the mixing elements can be welded via the supports to the exhaust pipe or to a separate housing, and the stability of the mixing element is maintained by means of the support and the mixing fins arranged thereon, even during increased exhaust gas throughput and increased heat input. Due to the separate assembly of each mixing element and due to the mixing lamellae, which are arranged on the corresponding support at a distance from one another and facing the exhaust pipe wall, an improved flow around the lamellae and thus improved mixing is achieved.

A static mixer or a distributor could also be advantageous if the static mixer has a plurality of mixing elements that are arranged next to one another transversely to the flow direction, and if the respective mixing element has a liquid oriented parallel to the flow direction ger and a plurality of mixing lamellae which are arranged on the carrier and are positioned relative to the carrier. Each carrier has two end surfaces and two connecting surfaces disposed between the two end surfaces and facing each other in the direction of the carrier and spaced from the end surfaces. The end surface and the first connecting surface of the respective carrier are connected to one another so that a portion of the carrier forms a closed cell, with at least two mixing lamellae being arranged on the carrier on the portion of the carrier that encloses the cell. As a result, the corresponding cell is not closed by a portion of a support on which no mixing lamella is arranged, and is arranged in front of the mixing lamella, which extends into the cell.

For a static mixer or a distributor, it could also be advantageous if the mixer has several flow elements for the exhaust gas, which are arranged next to one another transversely to the flow direction. The respective flow element is formed from a metal sheet with a wave-shaped cross-sectional profile which has a plurality of channels which extend adjacent to one another in the direction of parallel profile axes. The profile axis of the respective flow element is aligned with respect to the flow direction at an angle ms of up to 70° or at an angle ms of up to -70°. The profile axes of at least two flow elements arranged adjacent to one another are aligned at an angle ms, which are the same in direction and size. As a result, a fluid stream that reaches the center of the mixer and flows transversely to the flow direction is substantially caught by the two central flow elements having the same orientation and can be deflected in a different direction. The cross-sectional profile is preferably regularly wave-shaped, and the profile axes are all arranged parallel to one another.

A mixer for mixing an exhaust stream with a fluid injected into an exhaust line includes a first mixer element having a base connecting a first sidewall to a second sidewall spaced therefrom. The first and second sidewalls are sized and shaped to conform to an interior surface of the exhaust pipe so that the sidewalls are adapted to be attached to the exhaust pipe. The first mixing element includes a baffle arranged such that the injected fluid impinges thereon and a mixing fin arranged downstream of the baffle for mixing the exhaust gas with the injected fluid. A second mixing element has a base that connects a first and a second mounting flange spaced therefrom. The first and second mounting flanges are secured to the interior surfaces of the first and second sidewalls. The second mixing element has a mixing lamella for changing a flow direction of the exhaust gas stream.

Another mixer for mixing an exhaust gas stream with a fluid injected into an exhaust pipe has a tubular housing with circumferentially spaced slots extending from an open end of the housing. A first mixing element has a middle section that connects a first peripheral region with a second peripheral region spaced therefrom. The first peripheral region is arranged within one of the slots. The second peripheral region is disposed within another one of the slots. The flanges are attached to the housing. A second mixing element has a central section which connects a third and a fourth peripheral section spaced apart therefrom. The third and fourth peripheral portions are disposed in other of the slots and secured to the housing. The second mixing element is spaced apart from the first mixing element.

Further advantages and details of the invention are explained in the patent claims and in the description and shown in the figures.

BRIEF DESCRIPTION OF THE DRAWINGS

• 1 shows a view of a part of an exhaust system with an exhaust pipe and an injector, in which a mixer with a deflection element is arranged, which is adjusted with respect to the flow direction and which is not the subject of the claimed invention;
• 2 shows one 1 corresponding view with a mixer and a deflection element with correction plates;
• 3 shows one 1 corresponding view showing a mixer and a baffle constructed in a similar manner to a mixer;
• 4 shows a mirror-symmetrical mixer which is not the subject of the claimed invention;
• 5 shows a point-symmetrical mixer with a mixing element with a cell which is not the subject of the claimed invention;
• 6 shows a mixer arranged in an exhaust pipe according to 4 ;
• 7 shows a point-symmetrical mixer, which is not the subject of the claimed invention, with supports which are arranged at a distance from one another;
• 8th shows a side view of a carrier, which is not the subject of the claimed invention, with mixing slats that are positioned alternately;
• 9 shows a side view of a mixer according to 7 with a deflection element with correction slats;
• 9a shows a side view of a mixer according to 7 with a deflection element with drilled holes;
• 10 shows a view of a mixer, which is not the subject of the claimed invention, with flow elements which are in contact with one another;
• 11 shows three flow elements for a mixer according to 10 , which are arranged differently with respect to their respective profile axis;
• 12 shows a side view of a mixer according to 10 in an exhaust pipe with a pre-activated deflection element;
• 13 shows an angle diagram for the deflector and the injector;
• 14 shows an angle diagram for the mixing lamella with respect to the deflection element;
• 15 shows a perspective view of an alternative mixer, which is not the subject of the claimed invention;
• 16 shows another perspective view of the alternative mixer;
• 17 shows an end view of the alternative mixer;
• 18 shows a cross-sectional view of the mixer through line 18-18 in 17 ;
• 19 shows a partial cross-sectional view through line 19-19 in 18 ;
• 20 shows a side view of the mixer;
• 21 shows a perspective view of another alternative mixer which is not the subject of the claimed invention;
• 22 shows a perspective view of a mixer according to the invention;
• 23 shows a partial perspective view of an alternative mixer according to the invention;
• 24 shows a partial end view of the in 23 mixer shown;
• 25 shows a perspective view of an alternative mixer according to the invention;
• 26 shows a perspective view of the in 25 shown mixer viewed from a different angle;
• 27 shows an exploded perspective view of the in the 25 and 26 mixer shown; and
• 28 shows a partial cross-sectional view of a portion of an exhaust treatment system with an alternative mixer according to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

1 shows an exhaust pipe 40 as part of an exhaust system 4, which is not the subject of the claimed invention, in which a fluid is injected as a reducing agent via a flange 50 arranged on the exhaust pipe 40 in an injection direction E, and an injection device 5 arranged on the flange 50. For reasons of clarity, the figures show the central injection direction E and not the real, conical flow conditions shown in 3 are represented by the two dashed lines forming a V shape.

In the exhaust line 40, an exhaust gas flows essentially parallel to the exhaust line 40 in a flow direction S. For the sake of the description of the invention, it is assumed that the flow direction S extends in parallel in front of a deflection element 6 over the entire line cross section of the exhaust line 40.

Depending on the mass flow of the reducing agent, the reducing agent flows in the injection direction E into the exhaust line 40, more or less deflected by the exhaust gas flow. Downstream of the injection device 5 in the flow direction S there is a distributor which consists of a mixer 1 with a deflection element 6. The distributor is arranged in the exhaust pipe 40 via the mixer 1 and a flange connection 41.

The reducing agent largely hits the deflection element 6, so that the flow impulse of the reducing agent is reduced. The deflection element 6 is positioned at an angle sv with respect to the flow direction S, so that the exhaust gas flow is deflected by the deflection element 6 from the flow direction S into a distribution direction V. Due to this deflected exhaust gas flow, the reducing agent is entrained along the distribution direction V, partly before, but especially after, it hits the deflection element 6 hits, and is guided into the middle of the exhaust pipe 40.

2 shows a part of an exhaust system 4, which is not the subject of the claimed invention, as described with reference to 1 was described, with a mixer 1 with mixing fins 31 being integrated here, as generally in the 4 until 7 is presented in more detail. The deflection element 6 for such mixers 1 with mixing fins 31 is in 9 shown in more detail and has, as part of the deflection element 6, a sheet metal part 60 arranged parallel to the flow direction with a slat 61 which is set at the angle sv, and also correction plates 62 with correction slats 64.

The mixers 1 according to 4 , 6 and 7 have three mixing elements 3, which are not the subject of the claimed invention, which are arranged transversely to the flow direction S and each adjacent to one another, and one to two additional mixing elements 3a. The mixing element 3, 3a basically consists of a carrier 30, 30a and one or more mixing lamellae 31, 31a arranged thereon. The respective mixing lamella 31, 31a is attached to the carrier 30, 30a at its interface hR with respect to the flow direction S. Side boundary surfaces sR and a front boundary surface vR with respect to the flow direction S form free flow edges and are neither connected to another mixing lamella 31, 31a, nor to a housing 2 or an exhaust pipe 40.

The carrier 30 has an end surface 34 at both ends, in which no mixing lamella 31 is arranged, and which according to 7 is angled. The carrier 30 is, as in 7 is shown by way of example, via the two end surfaces 34 on a housing 2 or, as in 6 is shown, attached to an exhaust pipe 40. Between the two end surfaces 34, the carrier 30 hangs freely in the housing 2 or in the exhaust pipe 40, that is, it is neither supported or held by another structural element, nor does it support or hold another structural element. In addition, the supports 30 extend essentially parallel to one another in the areas between the end surfaces 34 and at a distance 35 of approximately 13.5 mm from one another.

The housing 2 is a cylindrical tube part, on the inner wall surface 20 of which mixing elements 3 and, depending on the exemplary embodiment, the additional mixing elements 3a are attached. A mixer 1 of this type is inserted with the housing 2 into an exhaust pipe 40 of an exhaust system 4, as in 2 is shown, and the exhaust gas flows through it in a flow direction S, which extends parallel to the central axis 23 of the housing 2.

The carrier 30 consists of a band-shaped sheet metal material with an in 8th defined width 32 and is aligned parallel to the flow direction S. The flow direction S denotes the main flow direction of the exhaust gas within the mixer 1 and extends parallel to the central axis 12 of the mixer and to the central axis 23 of the housing 2. Due to the fact that the carrier 30 is parallel to the flow direction S and thus parallel to the wall of the exhaust pipe 40 extends, the mixer 1 can simply be mounted transversely to the flow direction in the exhaust pipe 40.

In the exemplary embodiments according to 7 with three mixing elements, which are arranged essentially parallel and adjacent to one another and point-symmetrically, each of the mixing elements 3 is formed by a carrier 30 and four mixing lamellae 31. Therefore, the entire mixing element 3 consists of a carrier 30 and four mixing lamellas 31.

The carrier 30 can be divided into three portions 36 to 38 between the end surfaces 34. Outer portions 37, 38 each border a central portion 36 on opposite sides. Each of the outer subregions 37, 38 extends at an angle with respect to the middle subregion 36, i.e., the middle subregion 36 forms an angle α with each of the two outer subregions 37, 38. With respect to a first axis 11, which is parallel to the flow direction S extends, the two outer portions 37, 38 therefore intersect the middle portion 36 at an angle α of approximately 12°. The outer subregions 37, 38 are angled in opposite directions with respect to the central axis, so that the carrier 30 is point-symmetrical with respect to a central axis 12, which extends parallel to the flow direction S, i.e., the carrier 30 and the mixing lamellae 31 are designed and arranged point-symmetrically with respect to one another.

Like the three mixing elements 3, the three additional mixing elements 3a are also arranged in the areas near the mixing elements 3. The additional mixing element 3a is formed by a carrier 30a and a mixing lamella 31a. The additional mixing element 3a is fixed via its two end surfaces 34a to an inner wall surface 30 of the housing 2 and in a cantilever manner between the two end surfaces 34a.

With the exemplary embodiment of 4 the carrier 30 may according to the exemplary embodiment of 7 be divided into three subareas 36 to 38. The outer portions 37, 38 each border on opposite sides th to a central section 36. Each of the outer portions 37, 38 extends at an angle with respect to the middle portion 36, that is, the middle portion 36 forms an angle α with each of the two outer portions 37, 38. With respect to a first axis 11, which is parallel to the flow direction S extends, the two outer portions 37, 38 therefore intersect the middle portion 36 at an angle γ of approximately 9°. The outer partial regions 37, 38 are angled in the same direction with respect to the central axis 36, so that the carrier 30 is mirror-symmetrical with respect to a central plane 10 extending parallel to the flow direction S.

Due to the point symmetry, the flow on one side of the central plane 10 is deflected upwards and outwards in a direction transverse to the flow direction S, the opposite of the flow on the other side of the central plane 10. The flow is in 7 shown by arrows.

In the in the 4 until 9a In the exemplary embodiments shown, the mixing lamellae 31 form an angle β with respect to the direction of the carrier 30 and an angle ms with respect to the flow direction S. The mixing lamellae 31 are shown alternating. Like in the 8th and 9 As shown in more detail, the angle β is +135° or -135° and the angle ms is +45° or -45°. In addition, mixing lamellae 31, some of which are directly adjacent to one another, as in particular in 7 is shown, a regular distance 33 of at least 1 mm from each other.

In an exemplary embodiment, not shown, the adjacent end surfaces 34 are connected to one another by two adjacent supports 30. In addition, one end surface 34a of each of the additional mixing elements 3a is connected to one end surface 34 of the adjacent mixing element 3. This is achieved in that the three mixing elements 3 and the two additional mixing elements 3a are made from a single sheet metal strip.

A securing element 24 is arranged on an outside 21 of the housing 2, as shown in FIG 7 and 9 is shown. The securing element 24 is designed as a knob and protrudes from the outside 21. With the help of the securing element 24, the mixer 1 can be fixed in the exhaust pipe 40 against rotational movement about the central axis 23. In addition, the securing element 24 also serves to determine the rotational position of the mixer 1 with respect to the central axis 23 in the exhaust system 4 in the fixed state. For this purpose, a holder (not shown) is provided at a specific position into which the securing element 24 is pressed in the direction of the central axis 23.

According to 9 the mixer 1 is mounted with the housing 2 between two exhaust pipes 40, 40 '. For this purpose, the two exhaust pipes 40, 40 'are attached to the housing 2 on both sides. A space 42 is provided between the exhaust pipes 40, 40' for welding the two exhaust pipes 40, 40' to one another and for the weld connection of the exhaust pipes 40, 40' to the mixer 1. The gap 42 is created as a result of the fact that the exhaust pipes 40, 40' are spaced apart from one another in the direction of the central axis 12 by adjusting elements 22 distributed around the circumference, on which the respective exhaust pipe 40, 40' is positioned on one side in the direction of the central axis 12 adjoin each other.

The mixer 1 according to 4 and 6 is designed to be mirror-symmetrical with respect to a central plane 10 aligned parallel to the flow direction S, that is, the carrier 30 and the mixing lamellae 31 are designed and arranged to be mirror-symmetrical to one another. These mixers 1 have three mixing elements 3 which are arranged parallel and adjacent to one another, each of the mixing elements 3 being formed by a carrier 30 and one or three mixing lamellae 31 arranged on the carrier 30.

The carrier 30 can be divided into three portions 36 to 38 between the end surfaces 34. Outer portions 37, 38 each border a central portion 36 on opposite sides. Each of the outer portions 37, 38 extends at an angle with respect to the middle portion 36, i.e., the middle portion 36 forms an angle γ with each of the two outer portions 37, 38. With respect to a first axis 11, which is parallel to the flow direction S extends, the two outer portions 37, 38 therefore intersect the middle portion 36 at an angle γ of approximately 9°. The outer subregions 37, 38 are angled in the same direction with respect to the central subregion 36, so that the carrier 30 is designed to be mirror-symmetrical with respect to a central axis 12 extending parallel to the flow direction S.

The central mixing lamella 31 has a slot 39 in its middle, the length LS of which is between 50% and 80% of the length LM of the mixing lamella 31. Due to the slot 39, vortex formation is reduced because the flow is deflected to a lesser extent in the central region. In addition, the flow resistance of the mixer 1 is reduced precisely in the central region of the mixer 1, in which the mass flow is greatest.

In addition to the three mixing elements 3, an additional mixing element 3a is also arranged under the three mixing elements 3. The additional mixing element 3a is formed by a carrier 30a and a mixing lamella 31a, which also has a slot 39. The additional mixing element 3a is fixed via its two end surfaces 34a to the inner wall surface 20 of the housing 2 and in a cantilever manner between the two end surfaces 34a.

5 shows a point-symmetrical mixer 1, which is not the subject of the claimed invention, with two identical mixing elements 3, 3 '. The mixing elements 3, 3' each have two end surfaces 34, 340 and two connecting regions 370, 380 arranged between the end surfaces 34, 340. The end surface 34 and the first connection area 370 of the respective carrier 30 are connected to one another, so that a partial area 301 of the carrier 30 forms a closed cell 300. In the portion 301 of the carrier 30, which encloses the cell 300, two mixing lamellae 31 are arranged on the carrier 30. The mixing element 3 is attached to the exhaust pipe 40 via the end surface 340 and the second connection region 380.

The point-symmetrical mixer 1 according to the exemplary embodiments in the 5 and 7 can also be combined with a deflection element 6, the same also applies to the mirror-symmetrical mixer 1 according to the exemplary embodiments in the 4 and 6 . The deflection element 6 points, as in the 9 and 9a is shown, a sheet metal part 60 with one or more slats 61, which are set at an angle sv of approximately 20 °. The slats 61 deflect the exhaust gas flow upwards into a distribution direction V, so that the reducing agent is also carried upwards. The sheet metal part 60 is arranged directly on the carrier 30, 30a and, according to the exemplary embodiments shown, forms a construction element with the mixing element 3, 3a, which is a one-piece part made of the same material.

The deflection element 6 has a plurality of correction plates 62, 62 ', 62", which are arranged parallel to the flow direction S and parallel to the sheet metal part 60 and cause the reducing agent to be distributed directly in front of the mixer 1. The correction plate 62 is directly on the carrier 30 , 30a and, according to the illustrated exemplary embodiments, forms a structural element with the mixing element 3, 3a, which is a one-piece part made of the same material.

The correction plates 62, 62', 62" point according to 9 several correction slats 64, which are set at an angle sk of 155 ° with respect to the flow direction S. The correction blades 64 are, as in 14 is shown in detail, partially punched out of the correction plate 62 and protrude from the correction plate 62 in the direction of the adjacent correction plate 62 and / or in the direction of the sheet metal part 60. As a result, under the correction blade 64, an opening 63 is formed in the respective correction plate 62, which corresponds to the area of the correction blade 64 that protrudes from the correction plate 62. The correction lamella 64 can protrude from the correction plate 62 on one or both sides.

Likewise, the lamella 61 is punched out on the sheet metal part 60 in such a way that the sheet metal part 60 has an opening 63 under the respective lamella 61, which corresponds to the area of the lamella 61 protruding from the sheet metal part 60. As in 14 is shown, the correction lamella 64 protrudes from the correction plate 62 on both sides and the lamella 61 protrudes from the sheet metal part 60 on one side.

The correction plates 62, 62', 62" according to 9a Instead of correction lamellae, have several drill holes 65, which are aligned in a drilling direction B, which extends at an angle bs of 90 ° to the flow direction S, and through which the exhaust gas flow with the reducing agent at least partially passes through the deflection element 6 in the direction of the central axis 12 can stream.

3 also shows part of an exhaust system 4, which is not the subject of the claimed invention, as described with reference to 1 and 2 has been described, however, in this exemplary embodiment a mixer 1 is combined with a deflection element 6 constructed in a similar manner to the mixer 1 itself. A mixer 1 of this type is according to 10 formed from several adjacent flow elements 7, 7'.

11 shows in detail that the mixer 1 is constructed from a plurality of flow elements 7, 7', 7" which adjoin one another. The respective flow element 7, 7', 7" is formed from a metal sheet 70 with a wave-shaped cross-sectional profile 71, which has a front side 73 and a plurality of channels 72 which extend adjacent to one another in the direction of parallel profile axes 74. The profile axes 74, 74' of the two adjacent flow elements 7, 7' extend alternately at an angle ps of +40° and -40° with respect to the flow direction S. As a result, the flow in the channels formed by the two flow elements 7, 7' is simultaneously deflected upwards and downwards.

According to the invention, the profile axes 74', 74" of the two central flow elements 7', 7", which are adjacent with respect to the central plane 10, extend parallel, ie at an angle ps of -40°, which is the same in terms of direction and size , so that they are not adjacent to each other. As a result, as indicated by the arrows in 10 As is clear, the flow within the channels formed by the two flow elements 7', 7" is only deflected upwards, ie in the same direction. The angle ps corresponds to the angle ms in the exemplary embodiments described above.

Due to the same alignment of the profile axes 74', 74" of the two flow elements 7', 7", which are arranged opposite to one another with respect to the central plane 10 and at the same time adjacent to one another, a mirror-symmetrical geometry of the mixer 1 is obtained with respect to the central plane 10. The portion of the exhaust gas stream and the reducing agent that flows in the middle of the mixer 1 is thus deflected in one direction within these two flow elements 7 ', 7".

12 shows a cross section of a mixer 1, which is not the subject of the claimed invention, in which the profile axes 74, 74 'are set at an angle of ±30 °. A deflection element 6 is arranged in front of the mixer 1, which is constructed in a similar way to the mixer 1. With the deflection element 6, several sheet metal parts 60 with a cross-sectional profile 66 are also arranged directly adjacent to one another. Profile axes 67, 67' of the deflection element 6 of adjacent sheet metal parts 60 are not positioned with respect to the flow direction S, that is, they extend parallel to the flow direction S. The deflection element 6 therefore forms individual channels between the individual sheet metal parts 60 in accordance with the two central flow elements 7', 7" of the mixer 1, in which the exhaust gas flow and the reducing agent are guided in only one direction, which extends parallel to the flow direction S.

13 shows an angle diagram that represents the angles and angular relationships described above for the correction lamella 64 and the injection direction E together with the distribution direction V and the flow direction S. 14 shows such an overview with regard to the mixing fins 31 and the metal sheets 70 and the distribution direction V and the flow direction S.

The 15 - 20 show an alternative mixer designated by reference number 400, which is not the subject of the claimed invention. The mixer 400 has a first mixing element 402, a second mixing element 404, a third mixing element 406 and a fourth mixing element 408. The mixing elements 402, 404, 406, 408 are secured together to provide a mixer 400 as a one-piece unit. The first mixing element 402 functions as a holder or a housing as well as a mixing element. To achieve this function, the first mixing element 402 has a first arcuate sidewall 412 spaced from a second arcuate sidewall 414. A substantially flat base 416 connects the first sidewall 412 to the second sidewall 414 to define a “U” shape. The base 416 may be curved or have small bends to provide bend points 415, 417, as shown in the figures. The first sidewall 412 has a distal end 418 that is spaced from a distal end 419 of the second sidewall 414. The mixer 400 is arranged within the exhaust pipe 40 such that the gap between the ends 418, 419 is aligned with the injection device 5. A reagent that can flow along an upper interior surface of the exhaust conduit 40 is not hindered by the presence of a mixer wall, but will flow downstream between the ends 418, 419.

An integrally formed deflection element 420 extends axially from the base 416 substantially parallel to the flow direction S. The deflection element 420 has a plurality of correction blades 422 which are set at an angle A of 30° with respect to the flow direction. A mixing lamella 426 extends at an angle B of 45° with respect to the flow direction S. A slot 428 extends into the mixing lamella 426, so that the lamella is partially forked.

The second mixing element 404 has a first flange 430 that is spaced apart from a second flange 432. A base 434 connects the first flange 430 and the second flange 432. The base 434 extends substantially parallel to and offset from the base 416. The first flange 430 has an outer surface 438 that engages an inner surface 440 of the first sidewall 412 is arranged. The first flange 430 is attached to the first sidewall 412 using a process such as welding, riveting, or other mechanical fastening technique. Similarly, the second flange 432 has an outer surface 442 disposed in engagement with an inner surface 444 of the second sidewall 414.

The second flange 432 is attached to the second side wall 414. The second mixing element 404 also has one or more correction lamellas 450 which extend at an angle C of 40° with respect to the flow direction S. A mixing lamella 452 extends at an angle D of 40° in a direction opposite to the correction lamella 450. In the in the 15 until 20 In the embodiment shown, a single correction lamella 450 is arranged upstream of two laterally spaced mixing lamellas 452. Another partially bifurcated mixing fin 454 extends parallel to fin 426. Outer mixing fins 456 and 458 extend at an angle E of 45° with respect to the flow direction S. It is noted that the angle E does not have to be equal to the angle B, and that It is often advantageous for the mixing lamella 454 to extend in a non-parallel manner to the lamella 426. These angles can be changed to “adjust” the mixer 400 within a particular system to obtain the most even distribution of reducing agent possible.

The third mixing element 406 is substantially similar to the second mixing element 404. The third mixing element 406 has first and second flanges 464, 468. A base 470 connects the first flange 464 to the second flange 468. The base 470 is arranged such that it extends substantially parallel to the flow direction S and to the base 434. The first flange 464 and the second flange 468 are shaped and arranged such that they can be attached to the interior surfaces 440, 444 of the first mixing element 402. In a similar manner to the second mixing element 404, the third mixing element 406 includes a correction blade 474, a pair of laterally spaced mixing blades 476, a bifurcated mixing blade 478, and outer mixing blades 480, 482. The fins of this mixing element 406 extend substantially parallel to the similar fins of the second mixing element 404. It is noted that this relationship is merely exemplary and other angles may be defined.

The fourth mixing element 408 is substantially similar to the second mixing element 404 and the third mixing element 406. The fourth mixing element 408 has first and second flanges 486, 488. A base 490 connects the first flange 486 to the second flange 488. The base 490 is arranged such that it extends substantially parallel to the flow direction S and to the base 470. The first flange 486 and the second flange 488 are shaped and arranged such that they can be attached to the interior surfaces 440, 444 of the first mixing element 402. In a similar manner to the second mixing element 404, the fourth mixing element 408 includes a correction blade 494, a pair of laterally spaced mixing blades 496, a bifurcated mixing blade 498, and outer mixing blades 500, 502.

The fifth mixing element 610 has ninth and tenth flanges 684, 686 disposed in slots 688, 690 and attached to seventh and eighth lips 692, 694.

After each component among the second mixing element 404, the third mixing element 406 and the fourth mixing element 408 has been attached to the first mixing element 402, the mixer assembly 400 can be arranged within an exhaust conduit, such as in the exhaust conduit 40 described above. It is noted that the first sidewall 412 and the second sidewall 414 are sized and shaped such that they come into contact with or are arranged in close proximity to an interior surface of the exhaust pipe 40. The mixer 400 is disposed within the exhaust conduit 40 at a desired axial position and angular orientation and then secured thereto by any process such as welding, mechanical fastening, clamping, or the like.

21 shows a mixer according to the invention, designated by reference number 400a. The mixer 400a is substantially similar to the mixer 400 described above except that a first sidewall 412a has a substantially planar portion 413 disposed between the arcuate portions 415 and 417. The substantially flat portion 413 is spaced from an inner surface of the exhaust pipe 40, while the portions 415 and 417 are conformed to the inner surface and secured thereto by a process such as welding. Similarly, a second sidewall 414a has a substantially flat central portion 419 disposed between a curved portion 421 and another curved portion 423. The substantially flat middle section 419 is spaced from an inner surface of the exhaust pipe 40.

In the 22 until 24 Reference numeral 600 denotes another alternative mixer according to the invention. The mixer 600 has a plurality of transversely spaced mixing elements 602, 604, 606, 608 and 610. The mixer 600 includes a housing 612 that houses each of the mixing elements 602 to 610. The housing 612 may be a separate element and disposed within an exhaust pipe, or alternatively the element 612 may represent the exhaust pipe itself.

The housing 612 has an open end 614, from which several pairs of slots extend axially. A first pair of slots 616, 618 extend axially parallel to one another from the open end 614 over a predetermined distance and terminate at stop surfaces 617, 619. The slots 616, 618 can be formed as part of a stamping process in which cuts extending through the housing 612 are formed, whereupon the after internally protruding lips, such as a first lip 620 and a second lip 622, are formed by a tool. The first lip 620 extends substantially parallel to the second lip 622.

The first mixing element 602 has a first peripheral portion or flange 624 and a second peripheral portion or flange 626 spaced therefrom and substantially parallel. A base 628 connects the first and second flanges 624, 626 together. The first flange 624 extends into a slot 618 adjacent the first lip 620. Similarly, the second flange 626 extends into a slot 616 adjacent the second lip 622. The first and second flanges 624, 626 are welded or brazed to the first and the second lip 620, 622 attached. The outer ends of the flanges 624, 626 are sunk below a cylindrical surface 632 defined by the majority of the housing 612. In this way, the mixer 600 can be easily inserted into an exhaust pipe with a circular cross section. The base 628 is shown as being substantially planar and having a pair of axially extending ribs 636, 638. The ribs 636, 638 provide flexure points about which the first mixing element 602 can flex to compensate for an increase in element size caused by thermal expansion. It should be noted that any number of geometric features may be incorporated to achieve the desired flow and mixing characteristics. For example, it is contemplated that any of the mixing elements 602, 604, 606, 608, 610 may have one or more bends or protruding lugs, similar to the correction blade 450 and/or the mixing blades 476, 478 and 480, respectively.

The second mixing element 604 is substantially similar to the first mixing element 602 and includes third and fourth flanges 642, 644 that extend axially. A second pair of slots 646, 648 extend through housing 612 and receive third and fourth flanges 642, 644, respectively. The second mixing element 604 is attached to a third and a fourth lip 647, 649 of the housing 612.

A pair of opposing recesses 650, 652 are formed in housing 612. Slots 654, 656 extend through the housing 612 in the recesses 650, 652. Internally extending lips, such as lips 620, 622, are not formed from the housing 612 adjacent the slots 654, 656. Rather, the slot 654 is arranged between end surfaces 657, 659 of the housing 612, which are spaced apart from one another and face one another. The third mixing element 606 has fifth and sixth flanges 660 and 662 that extend substantially radially into the slots 654, 656.

The third mixing element 606 has a base portion 664 offset from radially extending peripheral portions or flanges 660, 662. The base portion 664 is connected to the radially extending flanges 660, 662 by angled walls 668, 670 to ensure that the mixer 600 withstands repeated heating and cooling events and is not affected by thermal expansion of the mixing elements. Each mixing element has a bend or geometric shape located radially outside the central planar base portion to provide a bend location. During heating, because the width of the central, substantially planar base portions increases, bending of each mixing element will occur as necessary to relieve stresses and minimize the load placed on the housing 612. It is also contemplated that one or more of the mixing elements may have a central base portion and peripheral portions that are coplanar. The housing will include a spring element to accommodate thermal expansion, such as a portion of a recess 650. In this configuration, no flex points are provided on the mixing elements.

Regarding the embodiment of the 22 - 24 Note that the peripheral portions or flanges 660, 662 are not directed upward, but rather extend substantially parallel to the base portion 664. Therefore, one surface of the flange 660 is disposed adjacent to the end surface 657, while the opposite surface of the flange 660 is disposed adjacent to the end surface 659. A similar arrangement exists for the flange 662 and the end surfaces defining the slot 656.

The fourth mixing element 608 is substantially similar to the second mixing element 604 except that its seventh and eighth flanges 674, 676, which are spaced apart, extend outwardly in an opposite direction as the third and fourth flanges 642, 644 . For this arrangement, fifth and sixth lips 678, 680 extend inwardly toward the third and fourth lips 647, 649.

Each of the mixing elements can be manufactured from a metal sheet using a stamping or forming process. The size and shape of the mixing elements can be standardized or individually adapted to a specific application. In addition, it should be noted that although the figures show a mixer with five mixing elements, other mixers are contemplated that have fewer or more mixing elements than the mixers shown. For example, they show 23 and 24 a mixer 600a. The mixer 600a is substantially similar to the mixer 600. Therefore, similar elements are denoted by similar reference numerals with an appended suffix “a”. The mixer 600a has a first mixing element 604a, a second mixing element 606a and a third mixing element 608a. The housing 612a has only the required number of slots to accommodate these mixing elements.

The 25 - 27 show an alternative mixer 700 according to the invention with first to sixth mixing elements 702, 704, 706, 708, 710 and 712. The mixing elements of the mixer 700 are substantially similar to the mixing elements of the mixer 400 and the mixing element 606 of the mixer 600, except that a body portion of each of the mixing elements is formed as a substantially planar flat plate with fins extending at an angle thereto. Each of the mixing elements 702-710 includes upwardly directed mixing fins designated by a suffix “a”. The mixing element 712 has an outwardly extending deflection element 716 with correction blades 712a which point in the opposite direction as the mixing blades 702a-710a. The mixing elements 704 to 712 also include a plurality of rear mixing blades disposed in a central portion of the mixing element and designated by a suffix “b”. Elements 704 through 710 also include rear, laterally spaced outer mixing fins designated by a suffix “c”. It is noted that the number of each type of mixing fins and the angle at which they extend from the substantially planar base portion may be specifically adjusted to optimally distribute the injected reagent within a particular exhaust treatment system.

Each mixing element includes a tongue portion having a reduced width, designated by the mixing element reference numeral with a suffix "d" appended, and extending coplanar with a body portion having a full width and designated by a suffix "e." The width of the tongue is reduced to leave out an inner, substantially cylindrical surface 718 of a ring 720.

The ring 720 has a plurality of depressions 724 extending radially inwards. Each recess has a slot 726 extending through the recess. The depressions and the slots are provided in pairs and are designated by suffixes “a” to “I”. The slots are labeled with the appropriate suffix according to the paired position. The reduced width tongue sections with the “d” suffix are inserted into the ring 720 first. The peripheral portions of the wider body portion with an “e” suffix extend through a corresponding pair of slots. For example, the peripheral portions of body portion 702e extend laterally into slots 726a and 726b. As described above with respect to the third mixing element 606, the axial position of each of the mixing elements 702 to 712 is determined by the length of the corresponding slots and an axial position of the transition between the tongue portions denoted by the suffix "d" and those denoted by the suffix "e". Body sections defined.

A spring element 730 is arranged on one side of each slot 726 and another spring element 732 is arranged on the opposite side of the slot 726. For the sake of clarity, in the 26 and 27 only spring elements 730b and 732b are shown. The spring elements 730, 732 bend radially outwards during a thermal event in which the temperature of the mixing element 702 increases and its width increases accordingly due to the linear thermal expansion. The remaining spring elements function similarly if the dimensions of their associated mixing element change with a change in temperature.

28 shows an alternative mixer 800 according to the invention. The mixer 800 has a mixer 802 which is essentially similar to one of the mixers described above, such as the mixer 1, the mixer 400, the mixer 600 or the mixer 700. In the mixer 800 the Mixer 802 combined with a secondary mixer 804 to improve reagent distribution in the exhaust line 40.

The mixer 802 has an uppermost rear mixing lamella 806, which is the in 18 Mixing lamella 500 shown or the one in 9a shown mixing lamella 31 is essentially similar. In the mixer 800, the mixing features of the mixer 802 are combined with a secondary mixer 804 to solve the problem that the injected reagent flows on or near an upper surface 810 of the exhaust conduit 40. The upper surface 810 is as a portion of the interior surface the exhaust pipe 40, which extends approximately downstream at the position where the injector 5 is angled away from the exhaust pipe. The secondary mixer 804 modifies the flow characteristics of the exhaust stream to improve reagent distribution downstream.

The secondary mixer 804 is shown as a substantially spherical projection 814 protruding radially inwardly from the top surface 810. The projection 814 has a location 816 of a maximum radially inner position that is recessed by approximately 10 percent with respect to the diameter of the exhaust pipe 40. The secondary mixer 804 is arranged to interact with the output stream of the mixer 802. In particular, a construction line 820 extending downstream from the mixing lamella 806 is shown. Construction line 820 intersects secondary mixer 804 at a position where projection 814 extends further radially inward. That is, the construction line 820 intersects the projection 814 at a location downstream of the location 816. In the specific example shown in the figure, the construction line 820 intersects the projection 814 at a location where 25 percent of the projection 814 lies upstream of the intersection, while 75 Percent of the projection 814 lies downstream of the intersection between the construction line 820 and the projection 814.

Advantageously, the secondary mixer 804, with its minimally inwardly directed projection, provides little to no back pressure contribution. The exhaust velocity distribution remains essentially the same while the reagent uniformity shows a 7 to 12% improvement over an arrangement that simply uses the mixer 802. Calculated fluid dynamics modeling indicates that the reagent concentration as well as the reagent distribution gradient are diffused through the use of the mixer 802 in combination with the secondary mixer 804. It is contemplated that the projection 814 is axially disposed such that the construction line 820 intersects the secondary mixer 804 at a location in the range of 10 percent to 50 percent of the axial length of the projection. In this manner, exhaust gas and reagent flowing along top surface 810 are deflected radially inwardly, while exhaust gas and reagent flowing along mixing fins 806 are deflected radially outward.

In the foregoing discussion, only exemplary embodiments of the present invention have been illustrated and described. It will be apparent to those skilled in the art from this discussion and from the accompanying drawings and claims that various changes, modifications and variations are possible within the scope of the invention as defined by the appended claims.

Claims (8)

Mixer (600, 600a, 700) for mixing an exhaust gas stream in an exhaust pipe, the mixer (600, 600a, 700) comprising: a tubular housing (612, 612a, 720) with circumferentially spaced slots (616, 618, 646, 648, 654, 656, 688, 690, 726a-i) extending through the housing (612, 612a, 720) for a predetermined axial length, the tubular housing (612, 612a) having radially inwardly extending depressions (650 , 652, 724a-i), which are arranged adjacent to the slots (654, 656), a first mixing element (602, 604a) having a central portion that connects a first peripheral portion (624) to a spaced-apart second peripheral portion (626). , wherein the first peripheral portion (624) is attached to one of the recesses (650, 652, 724a-i) associated with one of the slots (654, 656), wherein the second peripheral portion (626) is attached to another of the recesses (650 , 652, 724a-b) associated with another one of the slots (654, 656), and a second mixing element (604) having a central portion interconnecting third and fourth spaced peripheral portions (642, 644), the third and fourth peripheral sections (642, 644) are attached to other recesses associated with other of the slots (616, 618, 646, 648, 688, 690, 726a-i), the second mixing element (604) being separated from the first mixing element ( 602, 604a) is spaced apart. Mixer (600, 600a, 700). Claim 1 , wherein the recess (650, 652, 724a-i) includes a tab formed as a substantially planar plate. Mixer (600, 600a, 700). Claim 2 , wherein the first peripheral portion (624) of the first mixing element (650,724b) overlaps the tab. Mixer (600, 600a, 700). Claim 3 , further comprising a weld attaching the tab to the first peripheral portion (624), the tab being positioned radially inwardly from an outer surface of a housing (612, 612a). Mixer (600, 600a, 700). Claim 1 , wherein the recess (650, 652, 724a-i) extends on opposite sides of the slot (654, 656). Mixer (600, 600a, 700). Claim 1 , wherein an end face of the first peripheral portion (624) extends radially outwardly beyond an outer surface of the tubular housing (612, 612a). Mixer (600, 600a, 700). Claim 6 , further comprising a weld connecting the first peripheral portion (624) and the recess (650, 724b) along an outer surface of the tube housing. Mixer (600, 600a, 700). Claim 1 , wherein the housing (612, 612a, 720) has a front edge and an outer surface, the outer surface of the housing (612, 612a, 720) defining, proximate the front edge, a collar portion sized and shaped to closely fit an inner surface of the exhaust pipe, the recesses (650, 652, 724a-i) being positioned axially downstream of the collar portion.

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