DEVICE AND METHOD FOR INJECTING A MIXING GAS INTO AN EXHAUST LINE

Abstract

A device for injecting a mixing gas into an exhaust gas exhaust line of an engine, the device comprising: one or more inlet openings, a plurality of walls comprising: o a first wall (31) and; o a second wall (32) having one or more outlet openings and being arranged downstream of the first wall, and means (36) for injecting the mixing gas between the first wall and the second wall, so as to allow the mixing gas and the exhaust gases to be mixed between the first wall and the second wall.

Description

FIELD OF THE INVENTION

The invention relates generally to the injection of a mixing gas, and in particular to a device for injecting, for example into an exhaust gas exhaust line of an engine. The invention also relates to a related assembly, exhaust line and method.

PRIOR ART

Emissions of pollutants connected with transportation have been, for nearly thirty years, a leading progress driver of the industry. The gradual increase in the severity of the emission limits for the four regulated pollutants (CO, HC, NO_x, particles) has allowed a significant improvement in air quality, particularly in large urban areas.

The constantly increasing use of the automobile requires continuing efforts to reduce still further these pollutant emissions. Having highly effective remediation technologies available under all driving conditions is thus a major challenge for the transportation industry. In this context, the reduction of nitrogen oxides (NO_x) in a lean mixture, i.e. in a mixture having an excess of oxygen, represents an important challenge associated with a complex problem set.

Moreover, the consumption of fuel, directly connected with CO₂ emissions, has been driven in a few years to the level of a major automobile concern. Thus, regulations have been put in place at the European level beginning in 2012 regarding the CO₂ emissions of private vehicles. It is confirmed as of now that this limit will be regularly reduced during the coming decades. The reduction of CO₂ emissions has thus been imposed as the new progress driver for the entire transportation industry.

This dual problem of reducing local pollution (NO_x) and reducing fuel consumption (CO₂) is particularly difficult to resolve for the Diesel engine, whose combustion of lean mixtures is accompanied by NO_x emissions that are difficult to treat.

In this context, the technology of SCR (“selective catalytic reduction”) post-treatment is used both in private vehicles and in vehicles assigned to the transportation of merchandise. It is then possible to position the engine for its optimal efficiency operation, the strong NO_x emissions then being treated in the exhaust by the SCR system, allowing a highly effective reduction of NO_x.

SCR involves mixing an agent, for example a gas or a liquid, in particular a reducing agent such as a reducing gas, for example gaseous ammonia, with the exhaust gases and having the mixture pass in or over a catalyst placed in the exhaust line.

In the catalyst, the reducing agent transforms the nitrogen oxides into nitrogen and water. When the reducing agent is ammonia, NH₃, the reaction is the following:

4 NO+4 NH₃+O₂=4 N₂+6 H₂O

It is possible to inject a urea solution (hence a liquid), which is transformed into ammonia under the influence of the heat of the exhaust gases.

An aqueous solution of urea adopted and standardized for the operation of SCR systems currently in series production is designated AUS32 (the commercial name in Europe being Adblue

This very effective method suffers however from a certain number of disadvantages. It has limited effectiveness when cold, while such a situation occurs in several cases, particularly that of city buses. The urea reservoir has a considerable mass and volume, typically 15 to 30 L for a private vehicle, 40 to 80 L for a heavy cargo vehicle. Such a bulk causes complexity in integration into the vehicle that is greater if the vehicle is small. A high remediation cost results, as well as excess mass which is at the expense of the fuel consumption of the vehicle and therefore of CO₂ emissions.

The reducing agent can be injected in the form of a mixing gas. This is possible for example by storing the reducing agent, ammonia for example, in solid form, for example by absorbing the gas inside a material, a salt for example. The storage of the gas, ammonia for example, is then accomplished within the salt by the formation of a chemical complex of the ammine type.

The storage of mixing gas, for example a reducing agent, in the form of absorbed gas, has the advantage of a gain in volume with respect to a liquid, for example an aqueous solution, as well as increased effectiveness when cold, and greater compactness of the mixing zone with the exhaust gases, in particular.

If the agent is injected in the form of a mixing gas, it is difficult to mix it with the exhaust gas, which risks harming the effectiveness of the reaction of interest, SCR for example. A mixer can be positioned downstream of the injection, but the effectiveness of known devices remains limited.

Another problem associated with the injection of gas, for example gaseous ammonia, into the exhaust line, arises from the increasing bulk in the line as elements (catalysts, filter, injector, sensors, etc.) are added to it. This limits the possibilities for creating the elements necessary for a reaction, SCR for example.

SUMMARY OF THE INVENTION

One goal of the invention is to make more compact the elements associated with the injection and the mixing of gases along the exhaust line.

To this end, a device for injecting a mixing gas into an exhaust gas exhaust line of an engine is provided for, the device comprising for example:

• • one or more inlet openings,
  • a plurality of walls comprising:
    • a first wall, and
    • a second wall having one or more outlet openings positioned downstream of the first wall, and
  • means for injecting mixing gas between the first wall and the second wall,
    so as to allow mixing of the mixing gas and the exhaust gas between the first wall and the second wall.

Such a device is particularly compact. In particular, it no longer requires a mixer downstream of the injection, the injection device ensuring mixing of the mixing gas and the exhaust gases. In addition, the mixing is particularly effective.

The invention is advantageously completed by the following features, taken alone or in any of their technically possible combinations:

• • the plurality of walls comprises at least one intermediate wall positioned between the first wall and the second wall, the intermediate wall comprising one or more openings;
  • means for bypassing at least one zone, at one opening at least, configured to form a fluid communication between at least one opening of one wall of the plurality of walls upstream of the zone with at least one opening of a wall of the plurality of walls downstream of the zone without passing through the zone;
  • a lateral wall connecting the first wall and the second wall and delimiting, with the first wall, and the second wall, an interior space,
  • the injection device is adapted to be positioned in the interior of the exhaust line, so as to allow the passage of exhaust gas between the lateral wall and the wall of the exhaust line;
  • the lateral wall is distinct from the wall of the exhaust line;
  • the device comprises means of attaching the device to the exhaust line;
  • the device forms a section of the exhaust line,
  • the lateral wall is in contact with the exhaust line and/or forms a portion of the wall of the exhaust line;
  • mixing gas supply means of the injection means,
  • the attachment means comprise the supply means;
  • the first wall and/or the lateral wall has one or more inlet openings.
  • the injection means are positioned at the first wall and/or extend between the first wall and the second wall from the first wall;
  • for at least one wall of the plurality of walls, the dimensions of the openings and/or the total empty surface and/or the total empty surface density and/or the total empty volume density and/or the quantity of openings vary(ies);
  • the dimensions of the openings and/or the total empty surface and/or the total empty surface density and/or the total empty volume density and/or the quantity of openings of at least one wall vary(ies) with respect to at least one other wall of the plurality of walls.

The invention also relates to an exhaust line comprising such a device.

The invention also relates to an assembly comprising an engine and an exhaust system and/or line, the assembly comprising such a device.

The invention is advantageously completed by the following characteristics, taken alone or in any one of their technically possible combinations:

• • a selective catalytic reduction system for exhaust gases, and/or an oxidation catalyst

The invention also relates to a vehicle comprising such a device and/or such an exhaust line and/or such an assembly.

The invention also relates to a method of a mixing gas into an exhaust gas exhaust line of an engine implemented by means of such a device, comprising the following steps:

• • entry of the exhaust gases between the first wall and the second wall,
  • injection of the mixing gas between the first wall and the second wall,
  • mixing the entered exhaust gases and the injected mixing gas, - output of the mixed exhaust gases and mixing gas by at least one opening of the second wall.

BRIEF DESCRIPTION OF THE FIGURES

Other features and advantages of the invention will appear during the description hereafter of an embodiment. In the appended drawings:

FIG. 1 shows schematically an exhaust line according to one example of an embodiment of the invention,

FIG. 2 shows schematically a heat engine equipped with a selective catalytic reduction system for exhaust gases of an engine according to one example of an embodiment of the invention,

FIGS. 3a, 3b and 3c show schematically side, front and rear views of an injection device according to one example of an embodiment of the invention,

FIG. 4 shows schematically a perspective view of an injection device according to another example of an embodiment of the invention,

FIG. 5 shows schematically a perspective view of an injection device according to still another example of an embodiment of the invention,

FIGS. 6a, 6b and 6c show schematically walls according to examples of embodiments of the invention,

FIG. 7 shows schematically a side view of an injection device according to another example of an embodiment of the invention,

FIG. 8 shows schematically an injection method according to still another example of an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Exhaust Line and Assembly

With reference to FIG. 1, an exhaust gas exhaust line of an engine 1 is described, the exhaust line comprising a device for injecting a mixing gas into an exhaust gas exhaust line of an engine as described hereafter. Alternatively or in addition, an assembly comprising such an engine and/or such an exhaust line is described, the assembly comprising the injection device. Alternatively or in addition, a vehicle comprising such an exhaust line or such an assembly is described. The exhaust line comprises for example a wall.

For example, the mixing gas is or comprises a reducing gas, or is constituted essentially of a reducing gas. The reducing gas is for example gaseous ammonia and/or gaseous hydrogen. The mixing gas is or comprises oxygen for example.

The engine 1 is for example a heat engine. The heat engine can be an internal-combustion engine, for example a diesel engine, or a gasoline engine with a lean mixture, such as a direct injection engine with a stratified charge.

The engine 1 is for example equipped with a selective catalytic reduction system for exhaust gases, for example by means of a reducing gas, for example gaseous ammonia and/or hydrogen, as described hereafter.

The exhaust line or the assembly is for example configured so that, at the output of the engine 1, the exhaust gases 12 originating in the engine are for example directed toward a remediation system 2. The exhaust line or the assembly comprises for example the remediation system 2. The remediation system 2 can comprise an oxidation catalyst, for example a diesel oxidation catalyst, and/or a three-way catalyst. The remediation system 2 can also comprise a particle filter.

A device 3 for injecting mixing gas, for example ammonia and/or hydrogen and/or gaseous oxygen, into an exhaust gas exhaust line of an engine as described hereafter is for example positioned downstream of the outlet of the engine 1, for example downstream or upstream of the remediation system 2. The exhaust line or the assembly comprises for example the device 3.

What is meant by downstream is the flow direction of the exhaust gasses along the exhaust line, i.e. in the direction extending from the engine toward the exhaust outlet.

What is meant by upstream is the direction opposite to the flow of exhaust gases along the exhaust line, i.e. in the direction extending from the exhaust outlet toward the engine.

The device 3 allows injecting mixing gas at the exhaust line of the engine and mixing it with the exhaust gases. The device 3 allows for example forming a mixing gas/exhaust gas mixture 13. An additional mixer (not shown) can for example be added downstream of the device to further mix the mixing gas with the exhaust gases. However, the device 3 already allows mixing and the mixer is therefore no longer necessary, or can have its dimensions strongly reduced.

At least at the device 3, the exhaust line comprises a portion having a section in which the exhaust gases flow, this section being delimited by a wall of the exhaust line.

An SCR catalytic converter 4 can for example be positioned downstream of the device, for example downstream of the mixer. The exhaust line or the assembly comprises for example the SCR catalytic converter. The SCR catalytic converter is thus adapted for the mixing gas/exhaust gas mixture to pass through it. The SCR catalytic converter 4 is for example adapted to allow the reduction of the NOx by the mixing gas. The device 3 can for example form an SCR catalytic converter, so that the SCR catalytic converter can be omitted or be of reduced size.

At least one complementary post-treatment element 5, for example a plurality of such elements, can be positioned downstream of the SCR catalytic converter 4. The exhaust line or the assembly comprises for example the complementary element 5. The complementary element 5 can comprise a particle filter or an oxidation catalyst. The exhaust gases thus appear in the form of remediated exhaust gases 14 at the outlet of the complementary element 5. Alternatively or in addition, the SCR catalytic converter can comprise the complementary element 5. The SCR catalytic converter 4 can thus for example comprise a particle filter, in particular a diesel particle filter (DPF), so as to form an SCR catalytic converter with filter (SCRF, or “selective catalytic reaction on filter”). It is thus possible to accomplish an additional space saving by creating an exhaust line or a system without a complementary element 5 or with a complementary element 5 of reduced size.

The line can comprise an exhaust outlet 17 positioned downstream of the device 3, for example downstream of the SCR catalytic converter 4, for example downstream of the complementary element 5. The remediated exhaust gases are for example then directed toward the exhaust outlet 17. Thus the exhaust comprises, positioned from upstream on the engine 1 side, to downstream on the outlet 17 side, for example the remediation element 2, the device 3, for example the SCR catalytic converter 4, and for example the complementary element 5.

System and Assembly

With reference to FIG. 2, a system is described, for example a selective catalytic reduction system, for exhaust gases of such an engine 1, comprising such an injection device as described hereafter. Alternatively or additionally, an assembly comprising such an engine and such a system is described. Alternatively or additionally, a vehicle comprising such a system or such an assembly is described.

The engine 1 is for example controlled by an electronic computer 11. The system or the assembly comprises for example the electronic computer 11.

The system or the assembly can comprise a storage enclosure 8 for mixing gas, for example ammonia and/or gaseous hydrogen. The storage enclosure 8 can comprise and/or contain a storage structure 7. The storage structure 7 can for example be controlled in temperature by heating means 9, for example a heating element, of the system or of the assembly. It is thus possible to ensure a supply and a proportioning of the mixing gas at a mixing gas inlet 16 of the device 3, for example ammonia and/or hydrogen and/or gaseous oxygen. Alternatively or in addition, the heating means are or comprise for example means or an element for reheating and/or cooling. The heating means 9 comprise for example an electrical resistor or a heat exchanger supplied with a heat transfer fluid such as engine coolant liquid.

The heating means 9 allow for example supplying heat directly to the interior of the storage enclosure 8. Alternatively or in addition, the heating means 9 allow for example transmitting heat from the exterior of the enclosure 8 toward the interior of the enclosure 8.

In particular, the heating means 9 allow for example supplying heat to the storage structure 7.

The storage structure 7 comprises for example a material suited to allow solid storage of mixing gas. The material comprises for example a salt, such as an alkaline earth salt. The storage structure 7 comprises for example a layer of storage material, for example at least two layers of storage material, the storage material being for example a powdered salt, that at least two layers of powdered salt being for example separated from one another by at least one layer of a thermally conductive and/or deformable material.

The layers of the storage structure 7 can have coaxial rotational symmetry. The storage structure 7 can for example have a recess within it, for example along an axis of symmetry of revolution, to provide for storing and/or removal from storage of mixing gas at each layer of salt. The storage structure 7 can comprise channels for conveying the mixing gas, for example ammonia and/or hydrogen and/or gaseous oxygen, from the exterior of the storage enclosure 8 to the salt layers and/or in the opposite direction.

The heating means 9 can comprise one or more heating modules (not shown), each heating module being adapted to heat one layer of salt independently of the other heating module(s) and/or independently of the other salt layers.

The storage enclosure 8 is for example connected to a pressure control element 6 of the storage and/or mixing gas proportioning enclosure, for example ammonia and/or hydrogen and/or gaseous oxygen, to the device 3. This element 6 can be controlled by a dedicated electronic controller 10 connected to the electronic computer 11 of the engine. In an alternative configuration not shown, the element 6 can be directly controlled by the engine computer 11.

The element 6 is for example a valve, for example a solenoid valve.

The system or the assembly can thus comprise a mixing gas supply circuit, with for example ammonia and/or hydrogen and/or gaseous oxygen, comprising, from upstream to downstream in the mixing gas circulation direction, for example the storage enclosure 8, for example the element 6, and for example the device 3 for injecting mixing gas into the exhaust.

Device

General Structure

With reference to FIGS. 3a-c to 7, a device is described for injecting mixing gas, for example ammonia and/or hydrogen and/or gaseous oxygen, into an exhaust line of exhaust gas of an engine, for example the exhaust line and/or the engine as described above.

The device comprises for example a plurality of walls.

The plurality of walls comprises for example the a wall 31

The device comprises for example one or more inlet openings 311.

The first wall 31 has for example one or more inlet openings 311, for example the single inlet opening or the totality of inlet openings. The first wall 31 can thus form an inlet wall.

The plurality of walls comprises for example a second wall 32. The second wall 32 has for example one or more outlet openings 321. The second wall is for example positioned downstream of the first wall. The second wall 32 can thus form an outlet wall.

The device comprises for example means 36 for injecting the mixing gas, for example ammonia and/or hydrogen and/or gaseous oxygen. The injection means are for example adapted to allow the injection of mixing gas between the first wall and the second wall.

The injection means and/or the plurality of walls and/or the device is or are for example configured so as to allow mixing of the mixing gas and the exhaust gas between the first and the second wall.

The inlet opening(s) can also allow the exhaust gas coming from upstream in the exhaust line to penetrate into a space comprised between the first wall 31 and the second wall 32, where the mixing gas is also introduced. The plurality of the walls and the inlet 311 and outlet 321 openings allow limiting the space and the fluid circulation at the inlet and at the outlet of this space, so as to form a mixing zone. The outlet opening(s) 321 can thus allow the mixture of exhaust gas and mixing gas to leave the mixing zone in the direction of the exhaust outlet 17.

Such a device is particularly compact. In particular, it no longer necessitates a mixer downstream of the injection, the injection device ensuring the mixing of the reducing gas and the exhaust gases. In addition, the mixing is particularly effective.

Plurality of Walls

The plurality of walls can comprise at least one intermediate wall, for example a plurality of intermediate walls. Each intermediate wall is for example positioned between the first wall 31 and the second wall 32. Each intermediate wall can comprise one or more intermediate opening(s). It is thus possible to adapt the flow between the first wall 31 and the second wall 32 to improve the mixing between the mixing gas and the exhaust gases, for example by modulating or by controlling the flow, for example by limiting the reduction in the gas flow rate. The plurality of the intermediate walls can for example comprise a third wall 33 comprising one or more intermediate opening(s) 331 and a fourth wall 34 comprising one or more intermediate opening(s) 341.

The plurality of walls can thus comprise in all at least three walls, for example four walls, for example five walls, for example more than five walls, for example ten walls, for example more than ten walls.

The first wall 31 and/or the second wall 32 and/or the at least one intermediate wall, for example each wall of the plurality of walls, is for example separated from the adjacent wall(s) of the plurality of walls, for example separated from each other wall of the plurality of walls, for example so as to form with each adjacent wall a mixing zone.

The plurality of walls can thus form a stack of walls spaced from one another by at least one zone. The zone positioned directly downstream of the first wall, for example between the first wall and the second wall in the absence of an intermediate wall, or if not between the first wall and the farthest upstream intermediate wall, forms for example the first zone. In the case where the device comprises at least one intermediate wall, the following zone then forms the second zone, and so on by recurrence to the n^th zone, until the last zone which is the zone between the intermediate wall positioned farthest downstream and the second wall. Designated by n^th zone is thus at least one zone comprised between the first and the last zone, including the first zone and the last zone. At least one n^th zone forms for example an exchange zone between the exhaust gases entering the device and the mixing gas injected into the device.

The first wall 31 and/or the second wall 32 and/or the at least one intermediate wall, for example each wall of the plurality of walls, can comprise an upstream face turned upstream, and a downstream face turned downstream. The upstream face can form an inlet face. The downstream face can form an outlet face.

The first wall 31 and/or the second wall 32 and the at least one intermediate wall is for example flat and/or has a flat upstream face and/or a flat downstream face.

The first wall 31 and/or the second wall 32 and/or the at least one intermediate wall is for example curved and/or has a curved upstream face and/or downstream face, for example convex or concave. The first wall 31 is for example concave, the concavity being turned upstream. It is thus possible to concentrate the flow of exhaust gases, for example toward a central portion of the section of the device and/or of the exhaust line. The second wall 32 is for example concave, the concavity being turned downstream. It is thus possible to disperse the flow of exhaust gases, for example toward the exterior of the section of the device and/or of the exhaust line or over the entirety of the same section.

The first wall 31 and/or the second wall 32 and/or the at least one intermediate wall, for example each wall of the plurality of walls, has for example dimensions strictly smaller than those of the section of the exhaust line, or substantially equal to those of the section of the exhaust line. The exhaust line, for example of a motor vehicle, has for example a diameter comprised between 25 and 75 mm, for example approximately 50 mm.

The device can lack a lateral wall. In this case, the injection and/or mixing zone is defined by the plurality of walls, which influence the flow of the gases.

Alternatively, the device can also comprise a lateral wall 35. The lateral wall connects for example the first wall 31 and/or the second wall 32 and/or at least one intermediate wall, and/or all the walls of the plurality of walls. The lateral wall 35 delimits for example, with the first wall 31 and the second wall 32, an interior space. This interior space is for example the one in which are accomplished the injection of the mixing gases and the mixing with the exhaust gases. This interior space includes for example at least one n^th zone, for example all the n^th zones.

The lateral wall can be distinct from the exhaust line and the device comprising means for attaching the device to the exhaust line. In this case, the device can have at least in part a smaller section than that of the section of the exhaust line. The device can then for example have the shape of a knob.

The device 3 can extend over the entire section of the exhaust line, the lateral wall being for example in contact with the wall of the exhaust line and/or forming or being formed by a portion of the wall of the exhaust line.

The lateral wall is for example substantially cylindrical. The lateral wall has, for example, symmetry of revolution. The lateral wall can have, in cross section passing through the central axis of the portion of the exhaust line and/or through the axis of the device and/or through the axis of symmetry of the lateral wall, a straight and/or convex and/or concave wall.

The device 3 and/or the lateral wall 35 has for example a section, for example a substantially constant external and/or internal section, i.e. not varying more than 2% in surface.

The device 3 and/or the lateral wall 35 has for example a section, for example an external and/or internal section, that is strictly increasing or decreasing from upstream to downstream. The device 3 and/or the lateral wall 35 has for example a section in the shape of a truncated cone.

The device 3 and/or the lateral wall 35 has for example a section, for example an external and/or internal section, comprising an increasing or decreasing portion and a substantially constant section, for example only two such portions. The device 3 and/or the lateral wall 35 has for example a section, for example an external and/or internal section, comprising from upstream to downstream an increasing portion, shaped for example like a truncated cone, and a substantially constant section. The lateral wall 35 has for example one or more inlet openings, for example the sole inlet opening or the totality of the inlet openings. The lateral wall 35 can thus form an inlet wall. These inlet openings can be positioned upstream of the outlet opening(s).

The lateral wall is for example solid and lacking in lateral openings. Alternatively, the lateral wall has for example one or more lateral opening(s) 351. The lateral opening(s) 351 can thus also allow exhaust gases originating upstream of the exhaust line to penetrate into the space comprised between the first wall 31 and the second wall 32 where the mixing gas is also introduced. Alternatively or in addition, the or certain lateral opening(s) can also allow the mixture of exhaust gas and mixing gas to leave the mixing zone in the direction of the exhaust outlet 17.

The lateral openings can vary along the lateral wall 35, for example from upstream to downstream. Thus, possibly in combination with the plurality of walls, it is possible to further adapt the flow between the first wall 31 and the second wall 32 to improve the mixing between the mixing gas and the exhaust gases, for example by modulating or controlling the flow, for example by limiting the reduction of the gas flow rate.

The injection device is for example adapted to be positioned in the interior of the exhaust line, for example so as to allow the passage of exhaust gas out of the device, for example between the lateral wall and the wall of the exhaust line. It is thus possible to bring the exhaust gases directly downstream of the device 3, so that they can be mixed there with the mixture leaving the device 3 and thus form a second mixing zone downstream of the device 3.

The first wall 31 and/or the second wall 32 and/or the at least one intermediate wall, for example each wall of the plurality of walls, and/or the lateral wall 35, is for example formed by or comprises a plate.

The first wall 31 and/or the second wall 32 and/or the at least one intermediate wall, for example each wall of the plurality of walls, and/or the lateral wall 35, is for example made of metal, for example of stainless steel, for example of a composite material, for example of a ceramic, for example coated with a catalytic impregnation for the in situ remediation of the exhaust gases.

Opening

At least one inlet 311 and/or outlet 321 and/or intermediate 331 and/or 341 and/or lateral 351 opening, for example each of such opening, can be or comprise a through aperture. In the description, unless the contrary is stated, what is meant by opening is in particular an inlet 311 and/or outlet 321 and/or intermediate 331 and/or 341 and/or lateral 351 opening.

It is for example possible to modify the distribution and shape of the openings from one wall of the plurality of walls to another and/or along the lateral wall and/or from one n^th zone to another.

Each inlet 311 and/or outlet 321 and/or intermediate 331 and/or 341 and/or lateral 351 opening can have dimensions, for example substantially constant dimensions on the same wall and/or from one wall to another. The dimensions comprise or are for example the diameter and/or the length and/or the width.

The dimensions of at least one opening, for example of each inlet 311 and/or outlet 321 and/or intermediate 331 and/or 341 and/or lateral 351 opening are for example less than or equal to 5 cm, for example less than or equal to 1 cm, for example less than or equal to 5 mm, for example greater than or equal to 0.05 mm, for example greater than or equal to 0.1 mm, for example greater than or equal to 0.5 mm, for example on the order of 1mm, for example substantially equal to 1 mm.

For at least one wall of the plurality of walls, the dimensions, for example the diameter, of the at least one opening can vary, for example along a gradient, for example from the center to the periphery.

For example, the dimensions of the openings in a central zone of at least one wall of the plurality of walls can be greater than or equal, for example strictly greater, than those of a peripheral zone of the same wall. For example, the dimensions of the openings in a peripheral zone of at least one wall of the plurality of walls can be greater than or equal, for example strictly greater, than those of a central zone of the same wall. In particular, the dimensions of the openings of this wall can follow an increasing or decreasing gradient from the center to the periphery.

For example, the plurality of walls can comprise and alternation of one or more walls of which the dimensions of the openings in a central zone are greater than or equal, for example strictly greater, than those of a peripheral zone, and of one or more walls of which the diameter of the openings in a peripheral zone are greater than or equal, for example strictly greater, than those of a central zone. For example, the plurality of walls can comprise an alternation of one or more walls of which the diameter of the openings follow an increasing gradient from the center to the periphery and of one or more walls of which the dimensions of the openings follow a decreasing gradient from the center to the periphery.

Alternatively or in addition, the dimensions of the at least one opening of a wall of the plurality of walls, for example of the upstream of downstream face of this wall, can vary from one wall to another and/or with respect to another, at one other at least or at other walls of the plurality of walls, or be substantially the same.

For example, the dimensions of the openings of at least one wall of the plurality of walls can be greater than or equal, for example strictly greater, than those of the wall immediately upstream. It is thus possible to facilitate a suction effect and diffusion from upstream to downstream from the openings positioned upstream, which improves the diffusion of the mixing gas and/or of the exhaust gas from upstream to downstream and therefore their mixing.

For example, the dimensions of the openings of each wall of the plurality of walls can be greater than or equal, for example strictly greater, than those of the wall(s) of the plurality of walls upstream. This can allow a further increase in diffusion.

For example, the dimensions of the openings of at least one wall of the plurality of walls can be less than or equal, for example strictly less, than those of the wall immediately upstream. In this configuration, the dimensions of the apertures diminish from upstream to downstream, which allows increasing the pressure gradient from upstream to downstream, and thus cause perturbations in the flow and avoid or limit having a substantial portion of the flow passing directly through the device as if by the effect of a bypass. The perturbed flows thus allow favoring the mixing of mixing gas and exhaust gas within the device.

For example, the dimensions of the openings of each wall of the plurality of walls can be less than or equal, for example strictly less, than those of the wall(s) of the plurality of walls upstream. This can allow a further increase in the levels of turbulence via in particular the establishment of numerous recirculation zones.

For one wall of the plurality of walls, or a portion of said wall, a total empty surface is defined. The total empty surface can be defined as the surface occupied by the opening(s) of a wall, or of a portion of said wall, on the upstream face or the downstream face, or the average of these measured surfaces for the upstream face and the downstream face.

For one wall of the plurality of walls, or a portion of said wall, a total empty surface density is defined. The total empty surface density can be defined as the ratio of the surface occupied by the opening(s) of a wall, or of a portion of said wall, on the upstream face or the downstream face, or the average of these measured surfaces for the upstream face and the downstream face, with respect to the surface occupied by material at the upstream face or the downstream face, or the average of these measured surfaces for the upstream and downstream faces.

For one wall of the plurality of walls, or a portion of said wall, a total empty volume density is defined. The total empty volume density can be defined as the ratio of the volume occupied by the opening(s) of a wall, or of a portion of said wall, with respect to the volume occupied by material.

For one wall of the plurality of walls, or a portion of said wall, the number of distinct openings is defined as the quantity of openings.

For at least one wall of the plurality of walls, the total empty surface and/or the total empty surface density and/or the total empty volume density and/or the quantity of openings can vary, for example along a gradient, for example from the center to the periphery.

For example, the total empty surface and/or the total empty surface density and/or the total empty volume density and/or the quantity of openings in a central zone of at least one wall of the plurality of walls can be greater than or equal, for example strictly greater, than that of a peripheral zone of the same wall. The central zone is farther away from the periphery than the peripheral zone, for example the central zone is included in the smallest solid surface comprising the peripheral zone on the wall under consideration. The central and/or peripheral zone is for example an annular zone. For example the total empty surface and/or the total empty surface density and/or the total empty volume density and/or the quantity of openings in a peripheral zone of at least one wall of the plurality of walls can be greater than or equal, for example strictly greater, than that of a central zone of the same wall. In particular, the total empty surface and/or the total empty surface density and/or the total empty volume density and/or the quantity of openings of this wall can follow an increasing or decreasing gradient from the center to the periphery.

For example, the plurality of wall can comprise an alternation of one or more walls of which the total empty surface and/or the total empty surface density and/or the total empty volume density and/or the quantity of openings in a central zone is greater than or equal, for example strictly greater, than that of a peripheral zone, and of one or more walls of which the total empty surface and/or the total empty surface density and/or the total empty volume density and/or the quantity of openings in a peripheral zone is greater than or equal, for example strictly greater, than that of a central zone. It is thus possible, as illustrated in FIG. 5, to create currents alternately toward the center and toward the periphery of the device and/or of the exhaust line, which allows still better mixing and an extension of the distance over which the mixing takes place. For example, the plurality of walls can comprise an alternation of one or more walls of which the total empty surface and/or the total empty surface density and/or the total empty volume density and/or the quantity of openings follows an increasing gradient from the center to the periphery and one or more walls of which the total empty surface and/or the total empty surface density and/or the total empty volume density and/or the quantity of openings follows a decreasing gradient from the center to the periphery.

For example, the total empty surface and/or the total empty surface density and/or the total empty volume density and/or the quantity of openings of at least one wall of the plurality of walls can be greater than or equal, for example strictly greater, than that of the wall immediately upstream. It is thus possible to facilitate a suction effect and diffusion from upstream to downstream from the openings positioned upstream, which improves the diffusion of mixing gas and/or exhaust gas from upstream to downstream and therefore their mixing.

For example, the total empty surface and/or the total empty surface density and/or the total empty volume density and/or the quantity of openings of each wall of the plurality of walls can be greater than or equal, for example strictly greater, than that of the wall(s) of the plurality of walls upstream. This can allow a further increase in diffusion.

For example, the total empty surface and/or the total empty surface density and/or the total empty volume density and/or the quantity of openings of each wall of the plurality of walls can be less than or equal, for example strictly less, than that of the wall immediately upstream. In this configuration, the pressure gradient can increase from upstream to downstream, and thus cause perturbations in the flow and avoid or limit the fact that a substantial part of the flow passes directly through the device as if by the effect of a bypass. The perturbed flows thus allow favoring the mixing of mixing gas and of the exhaust gases within the device.

For example, the total empty surface and/or the total empty surface density and/or the total empty volume density and/or the quantity of openings of each wall of the plurality of walls can be less than or equal, for example strictly less, than that of the wall(s) of the plurality of walls upstream. This allows a further increase in the perturbations.

With reference to FIGS. 6a to 6c, one wall of the plurality of walls can comprise a central portion, substantially elongated for example, ovoid for example.

The wall can also comprise at least one radial portion, for example a plurality of radial portions 621, 622, 623, 624, extending from the central portion to the periphery. The radial portion is for example an arm, for example a segment. The radial portion is for example straight. The wall can for example comprise one, two, three or four radial portions perpendicular or parallel to one another, two by two.

The wall can comprise at least one peripheral portion 63, for example several peripheral portions 63, extending around the central portion 61, for example without discontinuity, for example so as to form an annular strip, for example defining an elongated shape, ovoid for example. Each peripheral portion 63 comprises for example a plurality of sections 631, 632, 633, 634, curved sections for example, connecting different radial portions. The peripheral portions can form different annular strips included inside one another.

The central portion 61 and/or the at least one radial portion and/or the at least one peripheral portion 63 are for example arranged so as to form between them the opening(s) of the wall under consideration.

With reference to FIG. 6a, the dimensions of the openings of this wall can follow an increasing gradient from the center to the periphery, the total empty surface and/or the total empty surface density and/or the total empty volume density can vary according to an increasing gradient from the center to the periphery. In particular, the spacing between the peripheral portions can follow an increasing gradient from the center to the periphery.

With reference to FIG. 6b, the spacing between the peripheral portion can follow a decreasing gradient from the center to the periphery.

With reference to FIG. 6c, the spacing between the peripheral portions can remain constant from the center to the periphery.

As illustrated in FIGS. 3b and 3c, at least one portion of the openings of a wall of the plurality of walls, for example all the openings of such a wall, are for example distributed in concentric circles.

From one wall to another, at least one portion of the openings of the walls of the plurality of walls is for example offset so as to modulate the flow.

Catalyst

The device can comprise a catalyst positioned in at least one nth zone, for example at least the last zone. The first wall 31 and/or the second wall 32 and/or the at least on intermediate wall, for example each wall of the plurality of walls, and/or the lateral wall 35, can be coated at least partially by a washcoat, the washcoat comprising for example a porous structure, the washcoat supporting a catalyst and/or the catalyst impregnating the washcoat, for example an SCR catalyst and/or an oxidation catalyst. It is thus possible for the device to provide an SCR catalytic conversion function and thus to eliminate or reduce in size the possible SCR catalytic converter positioned downstream. The catalyst can form a washcoat. The catalyst can coat at least one wall face turned toward the interior of the device, i.e. a wall face which is not the face turned toward the exterior of the first wall 31, the second wall 32 or the lateral wall 35, which in particular is not the upstream face of the first wall 31, the downstream face of the second wall 32 or the exterior face of the lateral wall 35. The zone at which the catalyst is positioned can thus form an SCR catalytic converter.

Bypass

The device can comprise means for bypassing, i.e. deriving, at least the n^th zone, for example a plurality of n^th zones, at one opening at least, configured to form a fluid communication between at least one opening of a wall of the plurality of walls upstream of the nth zone with at least one opening of a wall of the plurality of walls downstream of the nth zone without passing through the nth zone. The device can comprise a plurality of such means for bypassing the same nth zone or different nth zones. Such means for bypassing allow limiting the mixing in one zone to a portion of the flow, the other portion of the flow being reinjected only into a zone of the device situated downstream, or downstream of the device, to be mixed downstream.

The device can comprise means for bypassing or deriving the first zone and/or the second zone and/or the third zone and/or the nth zone and/or the last zone.

The bypass means comprise for example a duct, for example a tube, connecting the upstream opening and the downstream opening.

Injection Means

The injection means 36 comprise for example an injector, for example a multipoint injector. The injection means 36 comprise for example one branch, for example several branches. Each branch has for example one opening, for example a plurality of openings.

The injection means 36 are for example positioned, for example at least in part, at for example a central portion of the first wall 31 and/or of the second wall 32. It is thus possible to inject the mixing gas at a central section of the device.

The injection means are for example adapted to inject the mixing gas between the first wall 31 and an intermediate wall, for example the intermediate wall farthest upstream, for example the intermediate wall immediately downstream of the first wall 31. It is thus possible to form a first chamber of the device, for example the first zone, adapted for injection and a possible first mixing, and a second chamber of the device positioned downstream, for example downstream of the first zone, for more thorough mixing.

The injection means are for example adapted for injecting mixing gas into a plurality of nth zones, the injection varying for example from one zone to another, for example in terms of flow.

Alternatively or in addition, the injection means 36 are for example positioned, for example at least in part, at the lateral wall 35. This allows for example simplifying the injection or limiting the quantity of material necessary for its manufacture.

The injection means 36 may not extend, or may not substantially extend between the first wall 31 and the second wall 32. The injection means 36 can thus comprise one or more aperture(s) leading to the first wall 31 and/or the second wall 32 and/or the lateral wall 35.

Alternatively or in addition, the injection means 36 can extend between the first wall 31 and the second wall 32. The injection means 36 can for example extend in or along an intermediate wall. The injection means 36 can for example comprise an injection portion extending between the first wall 31 and the second wall 32. The injection portion comprises for example a perforated tube or a plurality of perforated tubes. Each perforated tube may comprise at least one aperture for injecting mixing gas, for example ammonia and/or hydrogen and/or gaseous oxygen, for example a plurality of apertures for injecting mixing gas.

The injection means 36 can for example extend from a central portion and/or from the center of the first wall 31 and/or of the second wall 32.

The device 3 and/or the exhaust line and/or the system can comprise supply means 361 for mixing gas, for example ammonia and/or hydrogen and/or gaseous oxygen, of the injection means. The supply means 361 comprise for example a supply duct.

Attachment

The device comprises for example means of attachment to the exhaust line and/or to the system, for example means for attachment to the wall of the exhaust line.

The attachment means comprise for example the injection means and/or the supply means.

The attachment means comprise for example means for attachment to the first wall and/or the second wall and/or at least one intermediate wall, for example positioned at the periphery of this wall or of these walls.

The first wall 31 and/or the second wall 32 and/or at least one intermediate wall is for example connected and/or attached to another wall of the plurality of walls by connection and/or attachment means between dedicated walls, these means being for example distinct from the lateral wall 35. The connection and/or attachment means between walls comprise for example a connection and/or attachment wall, for example in contact with and/or attached to a central portion of each connected and/or attached wall. The connection wall forms for example a tube. The attachment means of the device are for example in contact with attachment and/or connection means between walls to provide for the attachment of the device.

Examples of Devices

With reference to FIGS. 3a to 3c, such a device 3 is described. The arrow in FIG. 3a shows the flow direction. The first wall 31 and the second wall 32 are for example flat.

The first wall 31 and the second wall 32 have for example dimensions strictly smaller than those of the section of the exhaust line. The injection device is for example adapted to be positioned in the interior of the exhaust line, for example so as to allow passage of exhaust gas out of the device, for example between the lateral wall and the wall of the exhaust line.

The device can also comprise a lateral wall 35. The lateral wall connects for example the first wall 31 and the second wall 32. The lateral wall 35 delimits for example with the first wall 31 and the second wall 32 an interior space. This interior space is for example that in which are accomplished the injection of mixing gas and mixing with the exhaust gases. This interior space includes for example the first zone. The lateral wall can be distinct from the exhaust line and the device comprising the means for attaching the device to the exhaust line. In this case, the device can have at least in part a smaller section than that of the section of the exhaust line. The device can have for example the shape of a knob. The lateral wall is for example substantially cylindrical. The lateral wall has for example symmetry of revolution. The device 3 and the lateral wall 35 have for example a decreasing section.

Each wall of the plurality of walls is for example formed by or comprises a plate, of metal for example.

Each inlet 311 and/or outlet 321 opening can be a through aperture.

The total empty surface and/or the total empty surface density and/or the total empty volume density and/or the quantity of openings of the second wall can be strictly greater than that of the first wall. The first wall 31 can comprise fewer than twenty inlet openings 311, for example fewer than ten openings. The second wall 32 can comprise at least forty, for example at least fifty, for example at least sixty outlet openings 321.

The injection means 36 comprise for example an injector. The injection means 36 are for example positioned at a central portion of the first wall 31. The injection means 36 may not extend between the first wall 31 and the second wall 32. The device 3 and/or the exhaust line and/or the system can comprise mixing gas supply means 361 of the injection means. The injection means 361 comprise for example a supply duct.

The attachment means comprise for example the injection means and/or the supply means.

With reference to FIG. 4, another of such device 3 is described. The arrows in FIG. 4 show the flow direction and the flow lines. The first wall 31 and the second wall 32 are for example curved, for example convex or concave. The first wall 31 is for example concave, the concavity being turned upstream. It is thus possible to concentrate the flow of exhaust gases, for example toward a central portion of the section of the device and/or of the exhaust line. The second wall 31 is for example concave, the concavity being turned downstream. It is thus possible to disperse the flow of exhaust gases, for example toward the outside of the section of the device and/or of the exhaust line or over this entire section.

The first wall 31 and the second wall 32 have for example dimensions strictly smaller than those of the section of the exhaust line. The injection device is for example adapted to be positioned inside the exhaust line, for example so as to allow the passage of exhaust gases out of the device, for example between the lateral wall and the wall of the exhaust line.

The device can also comprise a lateral wall 35. The lateral wall connects for example the first wall 31 and the second wall 32. The lateral wall 35 delimits for example, with the first wall 31 and the second wall 32, an interior space. This interior space is for example that in which are accomplished the injection of mixing gas and mixing with the exhaust gases. This interior space includes for example the first zone. The lateral wall can be distinct from the exhaust line and the device comprising means for attaching the device to the exhaust line. In this case, the device can have at least in part a section smaller than that of the section of the exhaust line. The device can then have for example the shape of a knob. The lateral wall is for example substantially cylindrical. The lateral wall has for example symmetry of revolution. The lateral wall can have, in cross section passing through the axis of the device and/or through the axis of symmetry of the lateral wall, a straight wall. The device 3 and the lateral wall 35 have for example a substantially constant section. The lateral wall has for example several lateral openings 351.

Each wall of the plurality of walls is for example formed by or comprises a plate, of metal for example.

Each inlet 311 and/or outlet 321 and/or lateral 351 opening can be a through aperture.

Each inlet 311 and/or outlet 321 and/or intermediate 331 and/or 341 and/or lateral 351 opening can have substantially constant dimensions.

The injection means 36 comprise for example an injector. The injection means 36 can extend between the first wall 31 and the second wall 32. The injection means can for example comprise an injection portion extending between the first wall 31 and the second wall 32. The injection portion comprises for example a perforated tube. The device 3 and/or the exhaust line and/or the system can comprise mixing gas supply means 361 of the injection means. The supply means 361 comprise for example a supply duct.

The attachment means comprise for example the injection means and/or the supply means.

With reference to FIG. 5, yet another of such device 3 is described. The arrows in FIG. 5 show the flow direction and the lines of flow. The device 3 can comprise a plurality of intermediate walls. Each intermediate wall is for example positioned between the first wall 31 and the second wall 32. Each intermediate wall can comprise serveral intermediate openings. It is thus possible to adapt the flow between the first wall 31 and the second wall 32 to improve the mixing between the mixing gas and the exhaust gases, for example by modulating or by controlling the flow, for example by limiting the reduction in the gas flow rate. The plurality of intermediate walls can for example comprise a third wall 33 comprising several intermediate openings 331 and a fourth wall 34 comprising several intermediate opening(s) 341.

The plurality of walls can also comprise in total at least four walls, for example exactly four walls.

The first wall 31, the second wall 32 and the intermediate walls 33 and 34 are for example flat.

The first wall 31 and the second wall 32 have for example dimensions substantially equal to those of the section of the exhaust line. The injection device can extend over the entire section of the exhaust line.

The device can also comprise a lateral wall 35. The lateral wall connects for example the first wall 31, the second wall 32 and the two intermediate walls 33 and 34. The lateral wall 35 delimits for example, with the first wall 31 and the second wall 32, an interior space. This interior space is for example the one in which are accomplished the injection of mixing gas and the mixing with the exhaust gases. This interior space includes for example the first, second and third zones. The device 3 can extend over the entire section of the exhaust line, the lateral wall 35 being formed by a portion of the wall of the exhaust line. The lateral wall is for example substantially cylindrical. The lateral wall has for example symmetry of revolution. The lateral wall can have, in cross section passing through the central axis of the portion of the exhaust line, the axis of the device and/or through the axis of symmetry of the lateral wall, a straight wall. The device 3 and the lateral wall 35 have for example a substantially constant section.

Each wall of the plurality of walls and the lateral wall 35 are for example formed or each comprise a plate, of metal for example.

The plurality of walls can comprise an alternation of one or more walls the diameters of the openings of which follow an increasing gradient from the center to the periphery, for example the intermediate wall 33 and/or the second wall 32 and of one or more walls the diameters of the openings of which follow a decreasing gradient from the center to the periphery, for example the first wall 31 and/or the intermediate wall 34.

Alternatively or in addition, the plurality of walls can comprise and alternation of one or more walls of which the total empty surface and/or the total empty surface density and/or the total empty volume density and/or the quantity of openings follows an increasing gradient from the center to the periphery, for example the intermediate wall 33 and/or the second wall 32 and of one or more walls of which the total empty surface and/or the total empty surface density and/or the total empty volume density and/or the quantity of openings follows a decreasing gradient from the center to the periphery, for example the first wall 31 and the intermediate wall 34.

The injection means 36 comprise for example and injector. The injection means are for example adapted to inject the mixing gas, for example ammonia and/or hydrogen and/or gaseous oxygen, between the first wall 31 and the intermediate wall 33 immediately downstream of the first wall 31. The injection means 36 are for example positioned at the lateral wall 35. The injection means 36 may not extend between the first wall 31 and the second wall 32. The injection means can thus comprise a through aperture leading to the lateral wall 35.

With reference to FIG. 7, still another of such device 3 is described. The arrows in FIG. 7 show the flow direction and the lines of flow. The device 3 can comprise a plurality of intermediate walls. Each intermediate wall is for example positioned between the first wall 31 and the second wall 32. Each intermediate wall can comprise server intermediate openings. It is thus possible to adapt the flow between the first wall 31 and the second wall 32 to improve the mixing between the mixing gas and the exhaust gases, for example by modulating or by controlling the flow, for example by limiting the reduction of the gas flow rate. The plurality of intermediate wall can for example comprise a third wall 33 comprising several intermediate openings 331 and a fourth wall 34 comprising several intermediate opening(s) 341.

The plurality of walls can also comprise in total at least four wall, for example exactly four walls.

The first wall 31, the second wall 32 and the intermediate walls 33 and 34 are for example flat.

The first wall 31 and the second wall 32 have for example dimensions substantially equal to those of the section of the exhaust line. The injection device can extend over the entire section of the exhaust line.

The device can also comprise a lateral wall 35. The lateral wall connects for example the first wall 31, the second wall 32 and the two intermediate walls 33 and 34. The lateral wall 35 delimits for example, with the first wall 31 and the second wall 32, an interior space. This interior space is for example that in which are accomplished the injection of mixing gas and mixing with the exhaust gases. This interior space includes for example the first, second and third zones. The device 3 can extend over the entire section of the exhaust line, the lateral wall 35 being formed by a portion of the wall of the exhaust line. The lateral wall is for example substantially cylindrical. The lateral wall has for example symmetry of revolution. The lateral wall can have, in cross section passing through the central axis of the portion of the exhaust line of the device and/or through the axis of symmetry of the lateral wall, a straight wall. The device 3 and the lateral wall 35 have for example a substantially constant section.

Each wall of the plurality of walls and the lateral wall 35 are for example formed or each comprise a plate, of metal for example.

From upstream to downstream, the openings of the walls of the plurality of walls become smaller and smaller and more numerous, without however covering a larger surface. Thus, the dimensions of the openings of each wall of the plurality of walls can be less than or equal, for example strictly less, than those of the wall(s) of the plurality of walls upstream. The total empty surface and/or the total empty surface density and/or the total empty volume density of each wall of the plurality of walls can be strictly less than that of the walls of the plurality of walls upstream. The quantity of openings of each wall of the plurality of walls can be strictly greater than that of the walls of the plurality of walls upstream.

The device can comprise means for bypassing or deriving the first zone only. The device can comprise means for bypassing or deriving the first and the second zones only. The device can comprise means for bypassing the first, the second and the third zones. The bypass means comprise for example a duct, for example a tube, connecting the upstream opening and the downstream opening.

The injection means 36 comprise for example an injector. The injection means are for example adapted to inject the mixing gas, for example ammonia and/or hydrogen and/or gaseous oxygen, between the first wall 31 and the intermediate wall 33 immediately downstream of the first wall 31. The injection means are for example positioned at the lateral wall 35. The injection means 36 may not extend between the first wall 31 and the second wall 32. The injection means can thus comprise an aperture leading to the lateral wall 35.

Method

With reference to FIG. 8, a method of injecting mixing gas, for example ammonia and/or hydrogen and/or gaseous oxygen, into an exhaust gas exhaust line of an engine implemented by means of a device 3 as described above.

The method comprises for example a first step 801 of entering exhaust gases between the first wall 31 and the second wall 32, for example by at least one inlet opening 311 of the first wall. The exhaust gases thus penetrate into the injection and mixing zone, for example with a flow modified by at least one inlet opening 311 and/or the shape of the inlet wall 31.

The method comprises for example a second step 802 of injecting mixing gas, for example ammonia and/or hydrogen and/or gaseous oxygen, between the first wall 31 and the second wall 32. It is thus possible to place in contact, in the same space, the exhaust gas and the mixing gas.

The method comprises for example a third step 803 of mixing the entering exhaust gases and the injected mixing gas. Effective mixing directly during injection is allowed by the structure of the device which delimits a mixing zone.

The method comprises for example a fourth step 804 of output mixed exhaust and mixing gas by at least one opening of the second wall. It is thus possible to obtain a homogeneous mixture of mixing gas and exhaust gases, which no longer necessitates additional mixing or which will require a mixer with reduced dimensions.

Claims

1. A device for injecting a mixing gas into an exhaust gas exhaust line of an engine, the device comprising:

one or more inlet openings,

a plurality of walls comprising: a first wall, and a second wall having one or more outlet openings and positioned downstream of the first wall, and

injection means of the mixing gas between the first wall and the second wall, so as to allow mixing of the mixing gas and the exhaust gases between the first wall and the second wall.

2. The device according to claim 1, wherein the plurality of walls comprises at least one intermediate wall positioned between the first wall and the second wall, the intermediate wall comprising one or more openings.

3. The device according to claim 1, comprising means for bypassing at least one zone, at one opening at least, configured to form a fluid communication between at least one opening of a wall of the plurality of walls upstream of the zone with at least one opening of a wall of the plurality of walls downstream of the zone without passing through the zone.

4. The device according to claim 1, also comprising a lateral wall connecting the first wall and the second wall and delimiting with the first wall and the second wall an interior space, the injection device being adapted to be positioned inside the exhaust line, so as to allow the passage of exhaust gases between the lateral wall and the wall of the exhaust line.

5. The device according to claim 4, wherein the device comprises means for attaching the device to the exhaust line.

6. The device according to claim 1, the device forming a section of the exhaust line, in particular the device comprising a lateral wall connecting the first wall and the second wall and delimiting with the first wall and the second wall an interior space so that the lateral wall is in contact with the exhaust line and/or forms a portion of the wall of the exhaust line.

7. The device according to claim 5, comprising mixing gas supply means of the injection means, the attachment means comprising the supply means.

8. The device according to claim 1, wherein the first wall or the lateral wall has one or more of the one or more inlet openings.

9. The device according to claim 1, wherein the injection means are positioned at the first wall or extend between the first wall and the second wall from the first wall.

10. The device according to claim 1, wherein, for at least one wall of the plurality of walls, the dimensions of the openings or the total empty surface or the total empty surface density or the total empty volume density or the quantity of openings vary(ies).

11. The device according to claim 1, wherein the dimensions of the openings or the total empty surface or the total empty surface density or the total empty volume density or the quantity of openings of at least one wall vary(ies) with respect to at least one other wall of the plurality of walls.

12. An assembly comprising an engine and/or an exhaust gas exhaust line of the engine, the assembly comprising a device according claim 1.

13. The assembly according to claim 12, comprising a selective catalytic reduction system for exhaust gases, or an oxidation catalyst.

14. A method for injecting a mixing gas into an exhaust gas exhaust line of an engine implemented by means of a device according to claim 1, comprising the following steps:

entry of the exhaust gases between the first wall and the second wall,

injection of the mixing gas between the first wall and the second wall,

mixing the entered exhaust gases and the injected mixing gas,

output of the mixed exhaust gases and the mixing gas by at least one opening of the second wall.