US20110036082A1

US20110036082A1 - Exhaust element comprising a static means for mixing an additive into the exhaust gases

Info

Publication number: US20110036082A1
Application number: US12/989,769
Authority: US
Inventors: Cedric Collinot
Original assignee: Faurecia Systemes dEchappement SAS
Current assignee: Faurecia Systemes dEchappement SAS
Priority date: 2008-04-29
Filing date: 2009-04-23
Publication date: 2011-02-17
Also published as: DE112009001055T5; WO2009138668A3; FR2930594A1; WO2009138668A2; KR20110009685A; FR2930594B1

Abstract

The invention relates to an exhaust element including a line for exhausting the gases of a motor vehicle with a combustion engine and through the inside of which flows a fluid with the exhaust gases and of an additive to these gases. The exhaust element has, mounted inside it, a static device for mixing this additive with these exhaust gases. The static device for mixing the additive with the exhaust gases comprises at least one helicoid having an axis extending in a direction that makes a set angle with the direction of flow of the fluid through this exhaust element.

Description

RELATED U.S. APPLICATIONS

Not applicable.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

REFERENCE TO MICROFICHE APPENDIX

Not applicable.

BACKGROUND OF THE INVENTION

1. Field of the Invention
This invention relates to an exhaust element included in a line for exhausting the gases from a motor vehicle with a combustion engine.
This invention is related to the field of the automobile industry and, in particular, that of manufacturing equipment designed to ensure the exhausting of gases obtained from the burning of a fuel inside a combustion engine a motor vehicle includes.
Such equipment adopts the form of an exhaust line that, according to the direction of the flow of the exhaust gases in this exhaust line, on the one hand, is connected to such a combustion engine, on the other hand, comprises a succession of exhaust elements and, on yet another hand, opens onto the atmosphere.
In particular, among these exhaust elements, said exhaust line comprises at least one device for the physical and/or chemical treatment of exhaust gases.
Such a device may consist of a catalytic converter that can assume the form of a catalytic converter (in particular of the SCR type) for reducing nitrous oxides (NOx) and that comprises a means for treating the gases at least designed to ensure such a reduction. Such a catalytic converter finds its application in particular when it is necessary to clean up exhaust gases obtained from the burning of a fuel of the diesel type.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98.
It was found that the reduction of these exhaust gases inside such a catalytic converter is considerably improved when, before their introduction into this catalytic converter, these exhaust gases are mixed with an additive containing urea. In fact, urea, when it is introduced into hot exhaust gases (in particular after vaporization of a water solution of urea), undergoes a chemical transformation transforming it into ammonia (NH3) constituting a powerful reducer of nitrous oxides. Thus, inside the catalytic converter and in the presence of this ammonia, exhaust gases are reduced so that, at the exit of this catalytic converter, essentially water, hydrogen (H2) and nitrogen (N2) are released.
In this connection, it should be noted that the more homogeneous the mixing of the additive with exhaust gases is, the more effective is the reduction of these nitrous oxides.
In order to improve the homogeneity of this mixture, it is common to resort to a static mixer placed inside an exhaust element (usually an exhaust conduit) and upstream of the means for treating the gases.
As described in WO9300990, such a mixer adopts the form of a plurality of deflection elements that are, on the one hand, arranged according to a plurality of rows perpendicular to the axis of symmetry of the exhaust element and, on the other hand, oriented in the same direction inside the same row and in the opposite direction in two adjoining rows.
Also known, from EP-1.514.591, is an exhaust element comprising, inside, a static mixer comprising a plurality of zigzags adopting the form of bent strips of sheet metal extending from the periphery of this element toward its center. These zigzags define propeller blades extending through the exhaust element.
These devices permit, of course, to improve the homogeneity of the mixture downstream of the mixer but have however the disadvantage of creating a considerable back pressure upstream of this mixer, prejudicial to the flow of the gases in the exhaust line as well as to their treatment and to their evacuation.

SUMMARY OF THE INVENTION

This invention claims to be able to remedy the disadvantages of the state-of-the-art devices.
To this end, the invention relates to an exhaust element included in a line for exhausting the gases from a motor vehicle with a combustion engine and through the inside of which flows a fluid consisting of the exhaust gases as well as of an additive to these gases, this exhaust element comprising, mounted inside it, a static means for mixing this additive with these exhaust gases. This exhaust element is characterized in that the static means for mixing the additive with the exhaust gases comprises at least one helicoid having an axis extending in a direction that forms a set angle with the direction of flow of the fluid through this exhaust element.
An additional feature relates to the fact that the direction of extension of the axis of a helicoid forms, with the direction of flow of the fluid through the exhaust element, an angle between 0 and 30°.
According to another feature, the mixer comprises a plurality of helicoids having each an axis, on the one hand, extending in a direction that makes a set angle, in particular between 0 and 30°, with the direction of extension of the axis of another helicoid and, on the other hand, extending in a direction that makes a set angle, in particular between 0 and 30°, with the direction of flow of the fluid through this exhaust element.
According to an additional feature, the two helicoids that are immediately juxtaposed have an identical or, preferably, opposite direction of rotation.
An additional feature consists in that the mixer comprises a plurality of helicoids and that these helicoids are grouped together inside at least one set comprising at least two helicoids the direction of rotation of which is preferably identical.
According to another feature, the mixer comprises at least one module comprising, on the one hand, a plate oriented parallel to the direction of flow of the fluid through the exhaust element and, on the other hand, at least one helicoid or a set of at least two helicoids extending in the extension downstream of this plate.
In fact, this mixer comprises a plurality of modules, on the one hand, comprising each a plate as well as a set of at least two helicoids and, on the other hand, assembled, two by two, in particular perpendicularly, through assembling means comprised by at least one plate of at least one such module.
Finally, such a module consists of a single part, in particular a metallic part, preferably made by cutting out, boring, in particular completed by folding.
In fact, this exhaust element consists either of an exhaust conduit comprising, inside, the means for mixing an additive with the exhaust gases, or of a device for the physical and/or chemical treatment of exhaust gases comprising, inside, the means for mixing an additive with the exhaust gases as well as, downstream of this mixer, a means for the physical and/or chemical treatment of this mixture.
The invention also relates to an exhaust line comprising such an exhaust element.
The advantages of this invention consist in that the exhaust element comprises a static mixer for mixing the additive with the exhaust gases, such a mixer consisting of at least one helicoid placed inside this exhaust element. Such a helicoid permits, advantageously, to confer to the fluid a turbulent movement improving the homogenization of the mixture. Another advantage of such a helicoid consists in that the fluid, downstream of this helicoid, has a flow such that the back pressure generated by the mixture additive/exhaust gases is substantially lower than that generated by the state-of-the-art devices.
Additionally, such a mixer can also include a plurality of helicoids that are in fact cleverly arranged inside the exhaust element so as to adapt to the geometry and/or to the dimensions of the exhaust element which advantageously permits to optimize the flow of the fluid downstream of this mixture means.
Additionally, it is easily possible to adapt the number of helicoids, their positioning with respect to each other, their characteristics (direction of rotation, length, pitch, diameter, axis orientation), which advantageously permits to obtain good results in terms of homogeneity of the mixing and of weakness of the back pressure (and even in terms of compromise between this back pressure and head loss) downstream of the mixer.
In this connection, it should be noted that good results are obtained when this mixer comprises at least one pair of helicoids, and even preferably two pairs of helicoids.
An additional feature consists in that said mixer is placed inside an exhaust element consisting of an exhaust conduit or of a gas treatment device, in particular, a catalytic converter. Such an embodiment advantageously permits to position said mixer in an optimized manner within the exhaust line, with respect to the means for introducing the additive and with respect to the means for treating the exhaust gases.
Finally, this mixer can be made from at least one metal sheet, in particular by cutting out, boring, in particular completed by folding. This advantageously permits to provide a static mixer particularly effective for particularly reduced manufacturing costs.
Other aims and advantages of this invention will appear during the following description, referring to embodiments that are given only by way of an example, and non-restrictively.
The understanding of said description will be facilitated by referring to the drawings attached hereto.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of an exhaust line comprising an exhaust element according to the invention.

FIG. 2 is a schematic, partially cross-sectional, longitudinal view of an exhaust element consisting of an exhaust conduit and receiving, inside, a means for mixing (mixer) an additive with exhaust gases.

FIG. 3 is a schematic detailed view of such a mixer.

FIGS. 4 a and 4 b are schematic detailed views representing, respectively, each of the two modules constituting such a mixer.

FIGS. 5 a through 5 d are schematic detailed views corresponding to a first embodiment of the installation of such a mixer inside an exhaust element shown in FIG. 2.

FIGS. 6 a through 6 c are schematic detailed views corresponding to a second embodiment of the installation of such a mixer inside an exhaust element shown in FIG. 2.

DETAILED DESCRIPTION OF THE DRAWINGS

The invention is related to the field of the automobile industry and, in particular, that of manufacturing equipment designed to ensure the exhausting of gases obtained from the burning of a fuel inside a combustion engine 1 a motor vehicle includes.
Such equipment is in the form of an exhaust line 2, connected to this engine 1, comprising a plurality of exhaust elements (3; 4) following one another along this exhaust line 2.
In particular and as shown in FIG. 1, this exhaust line 2 can include at least one exhaust element 3 consisting of a device for ensuring the physical and/or chemical treatment of gases obtained from the burning of a fuel in the engine 1.
Such a treatment device 3 may consist of a particulate trap 31 (usually called FAP) placed downstream of the engine 1.
Such a treatment device 3 can also consist of a catalytic converter 32, also placed downstream of the engine 1. According to a first embodiment shown in FIG. 1 and corresponding to a standard configuration of an exhaust line 2, said catalytic converter 32 can be placed downstream of the abovementioned particulate trap 31. However, and according to another embodiment that is not shown, such a catalytic converter 32 can also be integrated into a more complex exhaust element 3 (usually called cata-FAP) incorporating such a catalytic converter 32 as well as a particulate trap 31 of the abovementioned type.
In fact, such a catalytic converter 32, in particular and at least partially, consists of a catalytic converter for the treatment of nitrous oxides (NOx) contained in the exhaust gases.
Such a catalytic converter 32 for treating nitrous oxides may consist of a catalytic converter for the trapping of these nitrous oxides (usually called NOx trap) or also of a catalytic converter for the catalytic reduction of these nitrous oxides, for example a three-way catalytic converter of the type TWC or also a catalytic converter of the type SCR (Selective Catalytic Reduction).
In the particular case of a catalytic converter 32 for reducing nitrous oxides, this catalytic converter 32 includes, inside, a means (in particular ceramic or analogous means) for the treatment of exhaust gases, said treatment means being designed to ensure the catalytic reduction of nitrous oxides contained in these gases.
In this connection, it should be noted that the catalytic reduction of nitrous oxides contained in exhaust gases is facilitated when these gases contain a reducing agent.
The presence in these gases of such a reducing agent can be ensured by introducing, inside the exhaust line 2 and upstream of the catalytic converter 32, such a reducing agent or the precursor of such a reducing agent which, inside the exhaust line 2 and upstream of the treatment means, is transformed into such a reducing agent.
To this end, the exhaust line 2 is complemented with a means 5 placed downstream of the particulate trap 31 and upstream of the catalytic converter 32, and designed to introduce (in particular by injection, more specifically after pulverization or vaporization) into this exhaust line 2 an additive that should be added to the exhaust gases for making a fluid to be treated by catalytic reduction in said catalytic converter 32.
This introduced additive consists of a reducing agent or of a precursor of such a reducing agent.
In fact, and according to a preferred embodiment, this additive is based on urea and may consist of a solution (in particular a water solution) having a small urea content, in particular known by the name of AdBlue (precursor of a reducing agent). This solution undergoes a chemical transformation (thermolysis, hydrolysis) inside the exhaust line 2 so as to be at least in the form of ammonia (NH3), constituting the reducing agent, mixed with the exhaust gases, inside the fluid to be treated.
It should also be noted that effectiveness of catalytic reduction of nitrous oxides contained in exhaust gases increases with the increase of homogeneity of the fluid to be treated by the catalyst 32.
In order to homogenize this fluid, the exhaust line 2 also includes a static means 6 for mixing the additive with the exhaust gases, this means 6, in the remaining part of the description and for convenience raisons, being referred to as mixer 6.
Such a mixer 6 is, in this case, designed for mixing exhaust gases with the additive consisting, as the case may be, of the reducing agent (in case of introduction of an additive consisting of such a reducing agent or after transformation into a reducing agent of a precursor—introduced in the line 2—of such a reducing agent) and/or of the precursor of such a reducing agent (in case of introduction of an additive consisting of such a reducing agent precursor).
In fact, and as shown in the attached Figures, said mixer 6 is placed, along the exhaust line 2 and inside the latter 2, between the means 5 for introducing the additive and the means for treating said fluid.
In this connection, and according to a first embodiment, not shown, such a mixer 6 can be placed inside an exhaust element 3 consisting of a device 3 for the physical and/or chemical treatment of exhaust gases the line 2 for exhausting the gases includes.
Said treatment device 3 includes, inside, the means 6 for mixing an additive with the exhaust gases as well as, downstream of this mixer 6, a means for the physical and/or chemical treatment of the mixed fluid.
Preferably, this device 3 for treating exhaust gases consists, in this case, of a catalytic converter 32 for catalytic reduction of nitrous oxides contained in exhaust gases or also of a more complex treatment device 3 of the abovementioned type (cata-FAP) comprising such a catalytic converter 32.
However, and according to a preferred embodiment of the invention, the means 6 for mixing an additive with the exhaust gases is mounted inside an exhaust element 4 consisting of an exhaust conduit 41.
As shown in the attached Figures, such an exhaust element 4 preferably consists of an exhaust conduit 41 for connecting a particulate trap 31 to a catalytic converter 32.
In fact, and as shown in FIGS. 5 a through 5 d and 6 a through 6 c, such a conduit 41 preferably consists of two portions (411; 412) of conduit 41, at least one 411 of which receives, inside, said mixer 6. The latter 6 is, in this case, introduced into this portion 411 of conduit 41, through its open end, and before connecting (in particular complemented with an integral connection, for example by welding) this portion 411 of conduit 41 to the other portion 412 of this conduit 41.
Irrespective of the nature (treatment device 3 or conduit 41) and/or the geometry of such an exhaust element (3, 4), the latter also includes, inside, a means 7 for receiving the mixer 6 inside this exhaust element (3, 4).
In fact, and as shown in FIGS. 5 a through 5 d and 6 a through 6 c, such a receiving means 7 preferably consists of a particular structure of the exhaust element (3, 4), in particular made by deformation of this exhaust element (3, 4), in particular of an open end a portion 411 of a conduit 41 constituting such an exhaust element 4 includes.
According to the invention, the means 6 for mixing the additive with the exhaust gases consists of at least one helicoid 61.
Such a helicoid 61 is at least characterized by a pitch, by a length, by a diameter, by a thickness, by a width, by an axis along which it extends and by a direction of rotation.
In this connection, it should be noted that the width of such a helicoid 61 can be constant, in the direction D of flow of the fluid through the exhaust element (3, 4). However, good results have been obtained for a helicoid 61 for which this width is increasing or, preferably, decreasing, in the direction D of flow of the fluid through the exhaust element (3, 4).
In fact, and according to another feature of such a helicoid 61, the latter has a width adapted to the structure of the exhaust element (3, 4) receiving at least one such helicoid 61. Such an embodiment advantageously permits to adjust the width of at least one such helicoid 61 to such a structure (in particular to the section of this exhaust element (3, 4), in particular in order to occupy the entire internal volume of the latter (3, 4).
Also, and according to another feature, such a helicoid 61 has an axis extending in a direction forming a set angle α with the direction D of flow of the fluid through this exhaust element (3, 4).
In this connection, it should be noted that the direction of extension of the axis of such a helicoid 61 forms with said direction D of flow of the fluid through the exhaust element (3, 4) an angle α between 0 and 30°.
According to a particular embodiment of the invention, not shown, said mixer 6 may consist of a single helicoid 61 placed inside an exhaust conduit 41 and the axis of which is at least parallel, in particular coinciding, with the axis of such a conduit 41.
However, and according to a preferred embodiment of the invention, this mixer 6 includes, in fact, a plurality of helicoids 61.
Such an embodiment advantageously permits to adapt the mixer 6 to the section of the exhaust element (3, 4) that it equips and/or to improve the quality of the homogenization of the fluid at the exit of the mixer 6.
By way of example, such a mixer 6 may include:

- two helicoids 61 for an exhaust element (3, 4) having a substantially rectangular cross-section;
- three helicoids 61 for an exhaust element (3, 4) having a substantially triangular cross-section;
- four helicoids 61 for an exhaust element (3, 4) having a substantially square (FIG. 6 c) or round (FIG. 5 d) cross-section.

Another feature of the invention consists in that these helicoids 61 each have an axis, on the one hand, extending in a direction forming a set angle α′ with the direction of extension of the axis of the other helicoid or helicoids 61 of the mixer 6 and, on the other hand, extending in a direction forming a set angle α with the direction D of flow of the fluid through this exhaust element (3, 4).
In this connection, it should be noted that the direction of extension of the axis of a helicoid 61 forms, in fact, with the direction of extension of the axis of another helicoid or helicoids 61, an angle α′ between 0 and 30°.
In a similar case, and as mentioned above, the direction of extension of the axis of such a helicoid 61 can also form with the direction D of flow of the fluid through the exhaust element (3, 4) an angle α between 0 and 30°.
A particular embodiment (shown in the attached Figures) consists in that the angles α and α′ are null, so the axis of a helicoid 61 is parallel to the direction of extension of the axis of the other helicoid or helicoids 61 of the mixer 6 as well as to the direction D of flow of the fluid through this exhaust element (3, 4).
In such a case, the extension axes of helicoids 61 are parallel between them.
However, and according to another configuration, not shown, these helicoids 61 can be arranged so that their extension axes diverge or, preferably, converge in the direction D of flow of the fluid through the exhaust element (3, 4).
As mentioned above, these helicoids 61 have a width that is constant, increasing or decreasing, and/or adapted to the structure of the exhaust element (3, 4), in the direction D of flow of the fluid through the exhaust element (3, 4).
This feature, combined with that of the direction of extension (in particular in a convergent or divergent manner) of the axes of these helicoids 61 advantageously permits to adjust these helicoids 61 to the structure of the exhaust element (3, 4) (in particular to the cross-section of the latter), in particular in order to occupy the entire internal volume of this exhaust element (3, 4).
According to an additional feature of the invention, the axes of these helicoids 61 are arranged according to a matrix (rectangular, triangular, square . . . ), in particular a regular one, with respect to the geometry (respectively rectangular, triangular, round or square . . . ) of the cross-section of this exhaust element (3, 4). Such an embodiment advantageously permits to optimize the positioning and the distribution of these helicoids 61 inside the exhaust element (3, 4), with respect to and depending on the structure of the latter (3, 4).
As mentioned above, each helicoid 61 has a direction of rotation.
In this connection, it should be noted that, according to an additional feature of the invention, two immediately juxtaposed helicoids 61, and even the entirety of helicoids 61 of the mixer 6, can have the same direction of rotation.
Such an embodiment is particularly advantageous when the fluid adopts a longitudinal turbulent movement (swirl) upstream of the mixer 6.
However, and according to a preferred embodiment of the invention (FIGS. 3, 5 d, 6 c), such immediately juxtaposed helicoids 61 preferably have a direction of rotation that is opposite (counter revolving helicoids). Such an embodiment advantageously permits to obtain a fluid to be treated that is optimally mixed.
Another feature of the invention consists in that the mixer 6 according to the invention comprises a plurality of helicoids 61 and that these helicoids 61 are grouped together inside at least one set (611; 612) comprising at least two helicoids 61.
In this connection, it should be noted that helicoids 61 of the same set (611; 612) of helicoids 61 have, as the case may be, a direction of rotation that is opposite (counter revolving helicoids) or (preferably) identical (FIGS. 3, 4 a, 4 b, 5 d, 6 c).
A particular embodiment, not shown, can consist of a mixer 6 comprising a single set of at least two helicoids 61, in particular adapted to an exhaust element 4 having a rectangular or oblong cross-section.
However, and according to a preferred embodiment of the invention, the mixer 6 includes, on the one hand, at least one set 611 (even a plurality of sets, preferably parallel) of at least two (or more) helicoids 61 aligned in a first set direction and, on the other hand, at least another set 612 (even a plurality of other sets, preferably parallel) of at least two (or more) helicoids 61 aligned in a second set direction, making an angle (preferably a right angle) with the first set direction.
In this connection, it should be noted that the number of these sets (611; 612), the number of helicoids 61 constituting such a set (611, 612) as well as the arrangement and the orientation of these sets (611, 612) are determined depending on the geometry of the exhaust element (3, 4) receiving the mixer 6, in particular in order to optimize the filling of the surface offered by the cross-section of the exhaust element (3, 4).
A preferred embodiment of the invention (shown in FIGS. 3 through 6 c) consists in that the mixer 6 comprises two sets (611; 612) of helicoids 61, in particular perpendicular, each comprising a pair of helicoids 61. In this embodiment, the two helicoids 61 of the same set (611, 612) have the same direction of rotation, whereas the two immediately juxtaposed helicoids 61 of two different sets (611; 612) may have the same direction of rotation but have preferably, as shown in FIGS. 3 through 6 c, a direction of rotation that is opposite.
Such a mixer 6 having four helicoids 61 can be placed inside an exhaust element (3, 4), either consisting of a device 3 for treating gases, as mentioned above, or consisting of an exhaust conduit 4 made based on a traditional (and most commonly used) design and which has a round cross-section (FIGS. 2 through 6 c).
In the latter case, the axes of said four helicoids 61 are preferably arranged according to a matrix that is square compared to the round geometry of the cross-section of the exhaust element 41.
According to a first embodiment shown in FIGS. 5 a through 5 d, these four helicoids 61 are placed inside a portion 411 having a round cross-section of said exhaust conduit 41.
However, and according to a preferred embodiment of the invention shown in FIGS. 6 a through 6 c, said four helicoids 61 are placed inside a specific portion 411′ having a square cross-section defined at the level of said exhaust conduit 41 having a round cross-section. Such an embodiment advantageously permits to increase the effectiveness of the mixer 6, diminishing the surface of the cross-section of the conduit 41 slightly (and even in no way) affected by the action of the helicoids 61, proportionally with respect to a round cross-section.
In fact, this portion 411′ having a square cross-section can be defined by deformation of the exhaust conduit 41 having a round cross-section, in particular by expansion.
According to another feature of the invention, these helicoids 61 have a diameter between 25 and 40% (preferably in the range of 35%) of the internal diameter (portion 411 having a round cross-section of the conduit 4) or of the maximum cross-section (portion 411′ having a square cross-section of the conduit 4) of the portion (411, 411′) of exhaust conduit 4 receiving these helicoids 61.
A preferred embodiment was described above regarding a mixer 6 comprising two sets (611, 612) each consisting of two helicoids 61. This invention is however in no way limited to such a configuration.
Also, and according to another embodiment, not shown, said mixer 6 can also include at least one set (611; 612) consisting of more than two helicoids 61 (in particular 3, 4 or more) arranged in alignment. Another embodiment can also consist of a mixer 6 comprising a plurality of sets comprising, for some at least, a different number of helicoids 61.
Thus, one can conceive a mixer 6 comprising, on the one hand, at least one set 611 (and even a plurality of sets, preferably parallel) comprising 3, 4 or more helicoids 61 aligned in a first set direction and, on the other hand, at least another set 612 (and even a plurality of other sets, preferably parallel) of at least two (or more) helicoids 61 aligned in a second set direction, making an angle (preferably a right angle) with the first set direction.
An additional feature consists in that these helicoids 61 have a length between 60 and 100 mm, preferably in the range of 80 mm, in particular 82 mm.
According to another feature of this invention, the static means 6 for mixing the additive with the exhaust gases comprises at least one module 62, each comprising, on the one hand, a plate (621; 622) oriented parallel to the direction D of flow of the fluid through the exhaust element and, on the other hand, at least one helicoid 61 or a set (611; 612) of at least two helicoids 61 extending in the extension downstream of said plate (621; 622).
In this connection, it should be noted that such a plate (621; 622) has two longitudinal sides and that, in particular, from one of said longitudinal sides (in particular the downstream longitudinal side) and in its extension extends at least one helicoid 61 or extend the helicoids 61 of a set (611; 612) of helicoids 61 a module 62 includes.
In fact, and according to a first embodiment, not shown, such a mixer 6 can include a single module 62 comprising a plate 621 as well as a helicoid 61 or a set of at least two helicoids 611.
However, and according to a preferred embodiment, said mixer 6 comprises a plurality of modules 62, on the one hand, each comprising a plate (621; 622) as well as a set (611; 612) of at least two helicoids 61 and, on the other hand, assembled, two by two, in particular perpendicularly, through assembling means 63 at least one plate (621; 622) of at least one such module 62 includes.
In this connection, it should be noted that said assembling means 63 consist, on the one hand, of an interlocking means 631, which a plate 621 is provided with, and, on the other hand, by a complementary interlocking means 632, which the other plate 622 is provided with.
As shown in FIGS. 4 a and 4 b, such an interlocking means 631 consists of a notch made in the upstream portion of a plate 621 (in particular at the level of the longitudinal side upstream of said plate 621), whereas the complementary interlocking means 632 consists of another notch made correspondingly in the downstream portion of the other plate 622 (in particular at the level of the longitudinal side downstream of said plate 622).
As shown in FIGS. 3, 5 d and 6 c, such an assembling is made so that the helicoid 61 of a set 611 of helicoids be, preferably, inserted between two helicoids 61 of another set 612 of helicoids 61, yet being offset laterally with respect to the direction of alignment of the two helicoids 61 of said other set 612.
Another feature consists in that a module 62 includes, at the level of at least one of the lateral edges of a plate (621; 622) of said module 62, a wing (641; 642) located in the extension of this plate (621; 622).
In the particular case of a mixer 6 comprising a single module 62, the two lateral edges of such a plate 621 can be prolonged by such a wing (641; 641′) that extends in fact laterally with respect to such a plate 621. These wings (641; 641′) advantageously constitute a means 8 for mounting the mixer 6 inside the exhaust element (3, 4), in particular by being received by the reception means 7 comprised by this exhaust element (3, 4) includes
In case of a mixer 6 comprising a plurality of modules 62, each of these modules 62 includes, at the level of at least one of the lateral edges of a plate (621; 622) of said module 62, a wing (641; 642) located in the extension of said plate (621; 622) and oriented in the direction of another wing (642; 641) the plate (622; 621) of another module 62 includes and which said wing (641; 642) can be made integral with, in particular by welding.
A preferred embodiment shown in FIGS. 3, 4A, 4 b, 5 d and 6 c consists in that the plates (621; 622) of each module 62 comprise, at the level of their two lateral edges, a wing (641, 641′; 642, 642′) located in the extension of such a plate (621; 622) and oriented in the direction of another wing (642, 642′; 641, 641′) the other plate (622; 621) includes and which said blades (641, 641′; 642, 642′) are or can be made integral with, in particular by welding.
In this connection, it should be noted that said wings (641, 641′; 642, 642′) advantageously constitute, in fact, a means 8 for mounting the mixer 6 inside the exhaust element (3, 4), in particular by being received by the receiving means 7 this exhaust element (3, 4) includes.
Another advantageous feature of the invention consists in that a module 62 as described above preferably consists of a single part, in particular a metallic part, preferably made by cutting out, boring, in particular complemented by folding.
The following are defined, in particular, at the level of such a single part:

- a plate (621; 622);
- at least one helicoid 61 or a set (611; 612) of at least two helicoids 61;

and, if such a module 62 includes an assembling means (63, 631, 632), at least one wing (641, 641′; 642, 642′).
As mentioned above, the exhaust element 3 comprising a mixer 6 having the abovementioned features may consist of a device 3 for the physical and/or chemical treatment of exhaust gases comprising, inside, the means 6 for mixing an additive with the exhaust gases as well as, downstream of this mixer 6, a means for the physical and/or chemical treatment of this mixture.
Such a treatment device 3 may consist:

- either of a catalytic converter 32 for the treatment of nitrous oxides (NOx) contained in the exhaust gases, in particular for catalytic reduction of said nitrous oxides (NOx), for example a three-way catalytic converter of the type TWC or also a catalytic converter of the type SCR (Selective Catalytic Reduction);
- or of a more complex exhaust element 3 (usually called cata-FAP) incorporating such a catalytic converter 32 as well as a particulate trap 31 of the abovementioned type.

However, and according to a preferred embodiment, the exhaust element 4 according to the invention preferably consists of an exhaust conduit 41 comprising, inside, the means 6 for mixing an additive with the exhaust gases having the abovementioned characteristics.
Finally, the invention also relates to a line 2 for exhausting the gases for motor vehicles with a combustion engine 1 and comprising, according to the direction of the flowing of the gases within said exhaust line 2, on the one hand, a means 5 for introducing into this exhaust line 2 an additive to be added to the exhaust gases, on the other hand, a static means 6 for mixing this additive with the exhaust gases and, on yet another hand, a means for the physical and/or chemical treatment of this mixture.
According to the invention, this exhaust line 2 comprises an exhaust element (3, 4) having the abovementioned features, and comprising said means 6 for mixing the additive with the exhaust gases. Said mixer 6 is interposed between the means 5 for introducing the additive into the line 2 and the means for treating the mixture (in particular comprised, inside, by a device 3 for the physical and/or chemical treatment of this mixture in case of an exhaust element 3 consisting of such a device 3).
This invention will find an application in the field of manufacturing equipment for exhausting the gases emitted by the engine 1 of a motor vehicle and obtained from the burning of a fuel, in particular of a fuel of the diesel type, inside such an engine 1.

Exemplary Embodiment

Output of the engine at full load: 600 kg/h at 600° C.
Mixer 6:

- two pairs of helicoids (611; 612);
- two helicoids of the same pair with the same direction of rotation;
- two helicoids of two different pairs with an opposite direction of rotation (counter revolving helicoids);
- pitch and length of helicoids: 82 mm
- diameter of helicoids: 21 mm
- exhaust element: a conduit having an internal diameter of 60 mm
- back pressure generated downstream of the mixer: 33 mbar

Claims

1. Exhaust element comprising:

a line for exhausting the gases of a motor vehicle with a combustion engine and through the inside of which flows a fluid being comprised of the exhaust gases as well as of an additive to these gases,

a static means mounted inside the exhaust element, for mixing this additive with these exhaust gases, wherein the static means for mixing the additive with the exhaust gases comprises at least one helicoid having an axis extending in a direction forming a set angle with the direction of flow of the fluid through this exhaust element.

2. Exhaust element according to claim 1, wherein the helicoid has an increasing width, in the direction of flow of the fluid through the exhaust element.

3. Exhaust element according to claim 1, wherein the helicoid has a decreasing width, in the direction of flow of the fluid through the exhaust element.

4. Exhaust element according to claim 1, wherein the direction of extension of the axis of a helicoid forms, with the direction of flow of the fluid through the exhaust element, an angle between 0 and 30°.

5. Exhaust element according to claim 1, further comprising: a mixer comprised of a plurality of helicoids, each helicoid having an axis, extending in a direction forming a set angle, in particular between 0 and 30°, with the direction of extension of the axis of another helicoid and extending in a direction forming a set angle, in particular between 0 and 30°, with the direction of flow of the fluid through this exhaust element.

6. Exhaust element according to claim 5, wherein the helicoids are arranged so that their extension axes diverge, in the direction of flow of the fluid through the exhaust element.

7. Exhaust element according to claim 5, wherein the helicoids are arranged so that their extension axes converge, in the direction of flow of the fluid through the exhaust element.

8. Exhaust element according to claim 5, wherein the axes of helicoids are arranged according to a matrix, in particular a regular one, with respect to the geometry of the section of the exhaust element.

9. Exhaust element according to claim 5, wherein two immediately juxtaposed helicoids have the same direction of rotation.

10. Exhaust element according to claim 5, wherein two immediately juxtaposed helicoids have an opposite direction of rotation.

11. Exhaust element according to claim 5, wherein the mixer comprises a plurality of helicoids and wherein these helicoids are grouped together inside at least one set comprising at least two helicoids having preferably the same direction of rotation.

12. Exhaust element according to claim 5, wherein the mixer comprises at least one module comprising a plate oriented parallel to the direction of flow of the fluid through the exhaust element and at least one or a set of at least two helicoids extending in the extension downstream of said plate.

13. Exhaust element according to claim 12, wherein the mixer comprises a plurality of modules, each module comprising a plate as well as a set of at least two helicoids and assembled, two by two, in particular perpendicularly, through assembling means at least one plate of at least one such module includes.

14. Exhaust element according to claim 13, wherein a module comprises, at the level of at least one of the lateral edges of a plate of said module, a wing located in the extension of said plate and oriented in the direction of another wing the plate of another module comprises, wherein said wing is made integral with, in particular by welding.

15. Exhaust element according to claim 12, wherein the module comprises a single part, in particular a metallic part, preferably made by cutting out, boring, in particular complemented by folding.

16. Exhaust element according to claim 5, wherein the exhaust element comprises a means for receiving the mixer.

17. Exhaust element according to claim 1, wherein the exhaust element comprises either of an exhaust conduit comprising, inside, the means for mixing an additive with the exhaust gases, or of a device for the physical and/or chemical treatment of exhaust gases comprising, inside, the means for mixing an additive with the exhaust gases as well as, downstream of this mixer, a means for the physical and/or chemical treatment of this mixture.