Reducing fluid mixer

Abstract

A mixer includes a reducing fluid injector, a disc-shaped injector, an elastic mat, and a hollow mixing chamber. The reducing fluid injector is configured to spray a reducing fluid into an exhaust gas flow. The reducing fluid injector is arranged along an axis. The disc-shaped injector support extends around the axis. The elastic mat is disposed on the disc-shaped injector support. The hollow mixing chamber extends around the axis and disposed on the elastic mat and separated from the disc-shaped injector support by the elastic mat. The hollow mixing chamber is tapered.

Description

REDUCING FLUID MIXERCROSS-REFERENCE TO RELATED APPLICATION

[0001] The present application claims priority to and the benefit of French Patent Application No. 2302689, filed March 22, 2023, the entire disclosure of which is hereby incorporated by reference herein.TECHNICAL FIELD

[0002] The present disclosure relates to a reducing fluid mixer for an exhaust line.BACKGROUND

[0003] An exhaust line transports exhaust gases from the outlet of an internal combustion engine to a nozzle which opens into the open air. Along the exhaust line, the exhaust gas purification equipment is arranged so that the gas discharged at the nozzle is as clean as possible. Purification equipment may be a selective catalytic reductor, or SCR. Such a catalyst purifies a mixture of exhaust gas and reducing fluid by catalytic reduction in that it transforms the nitrogen oxides, NOx, that it contains into non-polluting compounds, such as nitrogen, N2, and water, H2O. To this end it is advisable, upstream of the catalyst, to use a mixer which is able to thoroughly mix the exhaust gas with the reducing fluid. The reducing fluid is typically ammonia gas or a precursor thereof, such as an aqueous urea solution.

[0004] An exhaust gas flow passes through the mixer. It comprises a reducer injector able to spray reducing fluid into the exhaust gas flow.

[0005] According to one possible embodiment, the injector is arranged along an axis. The injector is carried by a substantially disc-shaped support around the same axis. The mixerfurther comprises a substantially tapered or cylindrical hollow mixing chamber around the same axis. This mixing chamber is arranged opposite and coaxially with the support. The exhaust gases enter the mixing chamber to be mixed therein with the reducing fluid, via perforations made in the support or in the walls of the mixing chamber or via a gap provided between the support and the mixing chamber.

[0006] The manufacturing tolerances, both of the support and of the mixing chamber, may lead to excessive deviations in the dimensions of this gap.

[0007] Thus, a means is sought to produce a repeatable gap between the support and the mixing chamber.

[0008] The mixer, in that it is integrated into an exhaust line and passed through by exhaust gases, is subject to very significant temperature variations. Thus, the mixer and the technical solutions implemented must be able to withstand significant dimensional variations by thermal expansion and high temperatures.SUMMARY

[0009] To this end, the present disclosure relates to a reducing fluid mixer for an exhaust line, able to be passed through by an exhaust gas flow, comprising a reducing fluid injector able to spray reducing fluid into the exhaust gas flow, arranged along an axis, a substantially discshaped injector support around the same axis and a substantially tapered or cylindrical hollow mixing chamber around the same axis, arranged opposite and coaxially with the support, where the mixer further comprises an elastic mat arranged between the support and the mixing chamber.

[0010] Particular features or embodiments, usable alone or in combination, are:- the mat is in metal mesh,- the mat has a substantially planar cross section substantially perpendicular to the axis,- the support comprises a cylindrical ring along the axis, coaxial with an axial end of the mixing chamber, and the mat has an L-shaped cross section, one branch of the “L” being substantially perpendicular to the axis and the other branch of the “L” being interposed between the axial end of the mixing chamber and the ring,- the ring comprises at least one first opening and the axial end of the mixing chamber comprises at least one second opening, arranged substantially opposite said at least one first opening,- the axial end of the mixing chamber comprises at least one leg able to come to bear axially against the mat,- said at least one leg comprises at least two legs,- the mixing chamber comprises at least one perforation, which is preferentially circular or oblong.

[0011] According to a second aspect of the present disclosure, an exhaust line comprising such a mixer.BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The present disclosure will be better understood on reading the following description, given solely by way of example, and with reference to the appended figures, wherein:

[0013] [Fig. 1] shows, in perspective view, a mixer according to a first embodiment,

[0014] [Fig. 2] shows, in perspective view, a mixer according to another embodiment,

[0015] [Fig. 3] shows, in top view, a mixer comprising several legs,

[0016] [Fig. 4] shows, in half axial cross sectional view, the detail of a mixer with a flat mat,

[0017] [Fig. 5] shows, in half axial cross sectional view, the detail of a mixer with an “L”- shaped mat,

[0018] [Fig. 6] shows, in perspective view, a mixing chamber comprising a leg,

[0019] [Fig. 7] shows, in perspective view, a mixer with a leg,

[0020] [Fig. 8] shows, in top view, a mixer with a leg,

[0021] [Fig. 9] shows, in perspective view, a mixer according to another embodiment,

[0022] [Fig. 10] shows, in perspective view, a mixer according to another embodiment.DETAILED DESCRIPTION

[0023] Referring to Figure 1, the present disclosure relates to a reducing fluid mixer 1 for an exhaust line. The mixer 1 comprises a hollow and substantially tapered or cylindrical mixing chamber 4 along an axis A. It also comprises an injector support 3, which is substantially discshaped about the same axis A, arranged opposite and coaxially with the mixing chamber 4. It also comprises a reducing injector 2 able to spray reducing fluid into the mixing chamber 4 in order to spray in the exhaust gas flow. The injector 2 is arranged along the same axis A, so as to spray the reducing fluid along this axis A.

[0024] The mixer 1 is able to be passed through be an exhaust gas flow. The exhaust gases quickly penetrate into the mixing chamber 4, from the outside to the inside. The exhaust gases enter by the generatrix of the cylinder or of the truncated cone, for example by means of vents 14. Fins 15 bordering the vents 14 allow a swirl to be created which promotes the mixing of the exhaust gases with the reducing fluid. They also penetrate into the mixing chamber 4 via a separation space provided between an axial end 9 of the mixing chamber 2 and the injector support 3 arranged opposite. At this separation space, openings 12, 13 and / or perforations 11 can be provided to allow the exhaust gases to enter. In the mixing chamber 4, the exhaust gases mix with the reducing fluid. The mixture obtained leaves the mixing chamber 4 by the other axial end of the mixing chamber 4.

[0025] The mixing chamber 4 is arranged opposite the support 3. These two parts are not attached to one another. However, the distance between the mixing chamber 4 and the support 3 should be controlled, in that this distance at least partially conditions a flow rate of exhaust gas entering the mixing chamber 4. It is important to control this flow rate in that it determines the flow rate of reducing fluid that must be injected.

[0026] Thus, according to one feature, the mixer 1 further comprises an elastic mat 5 arranged between the support 3 and the mixing chamber 4.

[0027] Because this mat has a compressive strength, it allows repeatable positioning of the mixing chamber 4 relative to the support 3.

[0028] In addition, the elasticity of the mat 5 allows absorption of the dimensional variations caused by thermal expansion.

[0029] According to another feature, the mat 5 is made of metal mesh.

[0030] According to another feature, more particularly shown in Figure 4, the mat 5 has a substantially planar cross section which is substantially perpendicular to the axis A.

[0031] Such a mat 5 makes it possible to form a stop allowing the mixing chamber 4 to be positioned axially, repeatedly, relative to the support 3.

[0032] According to another feature, more particularly shown in Figure 5, the mat 5 has a substantially “L”-shaped cross section. One branch 6 of the “L” is substantially perpendicular to the axis A. This part of the mat 5 forms a stop allowing the mixing chamber 4 to be positioned axially, repeatedly, relative to the support 3.

[0033] The support 3 advantageously comprises a cylindrical ring 8 along the axis A, coaxial with the axial end 9 of the mixing chamber 4. The other branch 7 of the “L” is substantially parallel to the axis A. Thus, it is interposed between the axial end 9 of the mixing chamber 4 and the ring 8. This part of the mat forms a centering guide allowing the mixing chamber 4 to be positioned radially, repeatedly, relative to the support 3

[0034] The exhaust gases enter into the mixing chamber 4 by the generatrix of the mixing chamber 4. Different types of bushings 11-14 are provided in order to allow, during the design, the input levels and the flow rates to be varied.

[0035] According to another feature, the ring 8 comprises at least one first opening 12. The axial end 9 of the mixing chamber 4, opposite the support 3, comprises at least one secondopening 13. Advantageously, said at least one first opening 12 is arranged substantially opposite said at least one second opening 13.

[0036] This allows the exhaust gas to enter the mixing chamber 5 by passing radially through the openings 12, 13 between the ring 8 and the mixing chamber 4.

[0037] According to another feature, the axial end 9 of the mixing chamber 4 comprises at least one leg 10 able to come to bear axially against the mat 5.

[0038] Such a single leg, more particularly shown in Figures 6-8, forms an axial stop, bearing against the mat 5, in order to position the mixing chamber 4 relative to the support 3.

[0039] According to another feature, said at least one leg 10 comprises at least two legs 10. This feature, which is more particularly shown in Figures 1-3, provides the same function as above. Increasing the number of legs allows improved lateral equilibrium of the mixing chamber 4, by multiplying the bearing points against the mat 5.

[0040] According to another feature, the mixing chamber 4 comprises at least one perforation 11, which is preferentially circular or oblong.

[0041] The present disclosure also relates to an exhaust line comprising such a mixer 1.

[0042] The present disclosure has been shown and described in detail in the drawings and the above disclosure. This must be considered as illustrative and given by way of example and not as limiting the present disclosure to this disclosure alone. Many alternative embodiments are possible.

[0043] List of reference signs

[0044] 1 : mixer,

[0045] 2: injector,

[0046] 3: support,

[0047] 4 : mixing chamber,

[0048] 5: mat,

[0049] 6: 1st branch,

[0050] 7 : 2nd branch,

[0051] 8: ring,

[0052] 9: axial end,

[0053] 10: leg,

[0054] 11 : perforation,

[0055] 12: 1st opening,

[0056] 13: 2nd opening,

[0057] 14: vent,

[0058] 15: fin,

[0059] A: axis.

Claims

WHAT IS CLAIMED IS:

1. A mixer compri sin : a reducing fluid injector configured to spray a reducing fluid into an exhaust gas flow, the reducing fluid injector arranged along an axis; a disc-shaped injector support extending around the axis; an elastic mat disposed on the disc-shaped injector support; and a hollow mixing chamber extending around the axis and disposed on the elastic mat and separated from the disc-shaped injector support by the elastic mat, the hollow mixing chamber being tapered.

2. The mixer of claim 1, wherein the elastic mat is made of metal mesh.

3. The mixer of claim 2, wherein the elastic mat has a planar cross section that is perpendicular to the axis.

4. The mixer of claim 1, wherein the elastic mat has a planar cross section that is perpendicular to the axis.

5. The mixer of claim 1, wherein the disc-shaped injector support comprises a cylindrical ring extending around the axis, the elastic mat, and an axial end of the hollow mixing chamber, the cylindrical ring being coaxial with the axial end.

6. The mixer of claim 5, wherein the elastic mat has an “L”-shaped cross-section such that a first branch of the “L”-shaped cross-section is perpendicular to the axis and a second branch of the “L”-shaped cross-section is interposed between the axial end and the cylindrical ring.

7. The mixer of claim 5, wherein: the cylindrical ring comprises at least one first opening; and the axial end comprises at least one second opening, the at least one second opening being arranged opposite the at least one first opening.

8. The mixer of claim 7, wherein the hollow mixing chamber comprises at least one perforation.

9. The mixer of claim 8, wherein each of the at least one perforation is disposed between one of the at least one second opening and the hollow mixing chamber.

10. The mixer of claim 5, wherein the axial end comprises at least one leg bearing axially against the elastic mat.

11. The mixer of claim 5, wherein the axial end comprises a plurality of legs, each of the legs bearing axially against the elastic mat.

12. The mixer of claim 1, wherein the hollow mixing chamber comprises at least one perforation.

13. The mixer of claim 12, wherein each of the at least one perforation is circular or oblong.

14. The mixer of claim 1, further comprising: a panel; and an exhaust conduit coupled to the panel; wherein the reducing fluid injector is coupled to the panel.

15. The mixer of claim 1, wherein the hollow mixing chamber comprises a plurality of vents.

16. The mixer of claim 15, wherein the hollow mixing chamber comprises a plurality of fins, each of the fins contiguous with one of the vents.

17. The mixer of claim 1, wherein the elastic mat is ring-shaped.

18. The mixer of claim 1, wherein: the elastic mat is made of metal mesh; the elastic mat has a planar cross section that is perpendicular to the axis; the disc-shaped injector support comprises a cylindrical ring extending around the axis, the elastic mat, and an axial end of the hollow mixing chamber, the cylindrical ring being coaxial with the axial end; the elastic mat has an “L”-shaped cross-section such that a first branch of the “L”- shaped cross-section is perpendicular to the axis and a second branch of the “L”-shaped crosssection is interposed between the axial end and the cylindrical ring; the cylindrical ring comprises at least one first opening; the axial end comprises at least one second opening, the at least one second opening being arranged opposite the at least one first opening; the axial end comprises at least one leg bearing axially against the elastic mat; the axial end comprises a plurality of legs, each of the legs bearing axially against the elastic mat; the hollow mixing chamber comprises at least one perforation; and each of the at least one perforation is disposed between one of the at least one second opening and the hollow mixing chamber.

19. The mixer of claim 1, further comprising: a panel; and an exhaust conduit coupled to the panel; wherein the hollow mixing chamber comprises at least one perforation; wherein each of the at least one perforation is circular or oblong; wherein the reducing fluid injector is coupled to the panel; wherein the hollow mixing chamber comprises a plurality of vents; wherein the hollow mixing chamber comprises a plurality of fins, each of the fins contiguous with one of the vents; and wherein the elastic mat is ring-shaped.

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