Exhaust gas purification device comprising an improved air inlet nozzle

Abstract

Exhaust gas purification device comprising an improved air inlet nozzle The end piece (20) is intended to equip an air inlet nozzle (18) for an exhaust gas purification device (10), in particular for a heat engine. It comprises a side wall (19) of general revolution shape, and at least one first air outlet orifice (24) formed in said side wall (19). Figure for the abstract: Figure 2

Description

Title of the invention: Exhaust gas purification device comprising an improved air inlet nozzle

[0001] The present invention relates to the field of exhaust gas purification devices, in particular for a heat engine. Such a purification device is intended to be arranged in the exhaust line of the heat engine.

[0002] For example, the heat engine equips a vehicle, in particular a motor vehicle, a public transport or freight transport vehicle, a marine vehicle, or any other conceivable vehicle. The heat engine can also equip a fixed installation.

[0003] The exhaust lines of vehicles equipped with thermal engines usually include catalytic purification devices, for example to convert NOx, CO and hydrocarbons into N2, CO2 and H2O. Such devices are generally only effective when the catalytic material is at a temperature above a predefined temperature threshold.

[0004] For this purpose, purification devices have been developed comprising a heating element mounted opposite the upstream face of a purification member, so as to accelerate the heating of the purification member when the vehicle is started.

[0005] Thus, we already know, in the state of the art, an exhaust gas purification device, in particular for a heat engine, comprising:

[0006] - a housing extending in a longitudinal direction,

[0007] - a purification member housed in the housing, and

[0008] - a heating element arranged near the purification member.

[0009] In order to improve such a purification device, it is known to arrange an air inlet nozzle opening into the housing, blowing air into the housing in particular in order to avoid overheating of the heating element.

[0010] The invention aims in particular to further improve such a purification device.

[0011] To this end, the invention relates in particular to an exhaust gas purification device, in particular for a heat engine, comprising a housing in which an exhaust gas is intended to circulate, a purification member housed in the housing, a heating element arranged close to the purification member, and an air inlet nozzle opening into the housing, characterized in that the nozzle is equipped with an end piece, the end piece comprising a side wall of general revolution shape, at least a first air outlet orifice being provided in said side wall.

[0012] The nozzle, arranged at the end of an air inlet nozzle, makes it possible to diffuse the air so as to spray the heating element as homogeneously as possible. This makes it possible both to cool the heating element, but also to diffuse the heat from the heating element towards the purification member as homogeneously as possible. Thanks to this homogeneous diffusion, the purification member does not have any overheated points. As a result, the service life of the purification member is increased. Furthermore, such homogeneous diffusion makes it possible to increase the maximum admissible power of the heating element. Thus, this advantageously results in a reduced catalysis initiation time.

[0013] A tip according to the invention may further comprise one or more of the following characteristics, taken alone or in any technically conceivable combination.

[0014] - The tip comprises a bottom wall, provided at a distal end of the tip.

[0015] - The nozzle comprises at least one second air outlet orifice provided in the wall background.

[0016] - Each second air outlet orifice of the bottom wall is chosen from: an orifice air outlet delimited by a straight edge and a curved edge whose ends are connected to those of the straight edge, and / or an air outlet orifice delimited by two parallel curved long edges, connected at their ends by two short edges, and / or a circular air outlet orifice.

[0017] - The side wall of the end piece has a generally truncated cone shape over at least a lower part of this tip.

[0018] - The tip comprises an upper part and a lower part separated by a collar.

[0019] - The side wall of the tip has, in the lower part, a surface in interior of general shape of revolution around an axis, the collar extending in a plane forming a non-right angle with respect to the axis.

[0020] - The nozzle comprises, in the upper part, an air inlet opening, and a duct widening from the air inlet opening to the lower part.

[0021] - The nozzle comprises an air inlet opening, having an inlet section air, each air outlet orifice having an air outlet section, such that the sum of the areas of the air outlet sections is between 20% and 200% of the area of ​​the air inlet section, preferably greater than 100%.

[0022] - The air inlet nozzle is oriented towards the heating element.

[0023] - The purification device only has a single air inlet nozzle.

[0024] Various aspects and advantages of the invention will be highlighted in the description which follows, given solely as an example and made with reference to the attached figures, among which:

[0025] [Fig.l] [Fig.l] is a schematic view of a purification device according to an exemplary embodiment of the invention;

[0026] [Fig.2] [Fig.2] is a perspective view of a tip of an air injection nozzle of the purification device of [Fig.l]; and

[0027] [Fig.3] [Fig.3] is an axial sectional view of the tip of [Fig.2].

[0028] [Fig. 1] shows a purification device 10 according to an exemplary embodiment of the invention, intended to equip a heat engine exhaust line.

[0029] The purification device 10 is arranged in the exhaust line between an upstream section and a downstream section. The terms “upstream” and “downstream” are considered as a function of the direction of circulation of the exhaust gases in the exhaust line.

[0030] The purification device 10 comprises a housing 12 extending in a longitudinal direction X, and delimiting a housing. The housing 12 is for example made of a metallic material.

[0031] The housing 12 comprises a central part 12A, an input part 12B, and an output part 12C.

[0032] The inlet portion 12B closes the housing on the upstream side, and the outlet portion 12C closes the housing on the downstream side.

[0033] The inlet portion 12B has a shape that widens from an inlet pipe 13 of the upstream section to the central portion 12A. The inlet portion 12B has, for example, a generally frustoconical shape, or any shape that widens.

[0034] The purification device 10 comprises a purification member 14, housed in the housing 12 so that the exhaust gases circulating in the housing 12 pass through this purification member 14. The purification member 14 is for example a three-way catalyst, a diesel oxidation catalyst, an SCR catalyst, or is of any other suitable type. The purification member 14 preferably has a general shape of revolution around an axis parallel to the longitudinal direction X.

[0035] Conventionally, the purification device 10 comprises a heating device, comprising a heating element 16, arranged close to the purification member 14, preferably upstream of the purification member 14.

[0036] The heating element 16 is housed in the housing 12. The heating element 16 is intended to preheat the purification member, in particular when the engine is switched on or before it is switched on.

[0037] Advantageously, the heating element 16 has a general shape of revolution defined around an axis parallel to the longitudinal direction X.

[0038] The heating element 16 is permeable to gas and in particular intended to be crossed by gases flowing in the longitudinal direction X (in particular exhaust gases, and air as will be described later), so that the gases are heated as they pass through the heating element 16.

[0039] Preferably, the heating element 16 is formed by a metal grid. Alternatively, the heating element 16 may be made of a metal foam, or any other suitable heating element, such as a honeycomb body. More particularly, the heating element 16 may be formed by any resistive element capable of transforming an electric current into heat.

[0040] The heating element 16 extends over the entire passage section of the housing 12, so that the gases circulating in the housing 12 necessarily pass through the heating element 16. The gases are thus heated uniformly.

[0041] Conventionally, the heating element 16 comprises at least one, preferably two electrical poles, by which the heating element 16 is intended to be electrically powered. For this purpose, each of these electrical poles is intended to be connected to a respective electrode.

[0042] The purification device 10 according to the invention comprises at least one air injection nozzle 18, intended to inject air into the housing. Preferably, the purification device 10 comprises only a single injection nozzle 18.

[0043] The air blown in by the injection nozzle 18 makes it possible in particular to diffuse the heat energy during the preheating of the purification member 14 by the heating element 16.

[0044] Advantageously, the injection nozzle 18 is arranged to pass through the inlet part 12B of the housing 12.

[0045] The injection nozzle 18 is oriented in the direction of the heating element 16, that is to say that the air flow injected by the injection nozzle 18 has a component, along the longitudinal axis X, oriented in the same direction as the direction of circulation of exhaust gas in the housing 12, from upstream to downstream. The fact that the nozzle 18 is oriented to blow the air in the same direction as the flow of exhaust gas makes it possible to reduce the impact of the air flow on the circulation of the exhaust gases, and not to generate backpressure or thermomechanical constraints on the nozzle 18. This is particularly the case for the passive phases of the heating element 16, that is to say when the engine is in normal operation, and this is all the more true for the phases of full engine load. The purpose of this orientation is to minimize the deviation (masking) of the flow generated by the motor on the heating element 16 as well as on the purification member 14.

[0046] The injection nozzle 18 comprises a tip 20 intended to optimize the diffusion of air towards the heating element 16.

[0047] The end piece 20, shown in more detail in Figures 2 and 3, comprises a wall lateral 19 of general shape of revolution.

[0048] The end piece 20 extends along an axis A. In this example described, the side wall 19 has a general shape of revolution around the axis A.

[0049] The end piece 20 comprises an upper part 20A, intended to be arranged outside the housing 12, and a lower part 20B, intended to extend inside the housing 12. Thus, the end piece 20 passes through an opening 21 formed in the inlet part 12B.

[0050] Advantageously, the end piece 20 comprises a collar 22 separating the upper 20A and lower 20B parts. This collar 22 is intended to come into contact with the edge of the opening 21. The collar 22 makes it possible to ensure the assembly by welding of the end piece 20 on the inlet part 12B while avoiding the projection of solder particles inside the purification device.

[0051] The collar 22 is preferably inclined relative to the axis A, that is to say that it extends in a plane forming a non-right angle with the axis A. The inclination of the collar 22 therefore imposes the orientation of the end piece 20 inside the housing 12, that is to say the orientation of the lower part 20B. The person skilled in the art designing the end piece 20 will easily be able to choose the inclination of the collar 22 as a function of the desired orientation for the lower part 20B.

[0052] More particularly, in the lower part 20B, the side wall 19 has an inner surface 19A and an outer surface 19B. In the example described, the inner 19A and outer 19B surfaces are concentric, both having a general shape of revolution defined around the axis A. However, as a variant, only the inner surface 19A has a general shape of revolution defined around the axis A, the shape of the outer surface 19B being less important for the diffusion of air.

[0053] In a preferred embodiment, the tip 20 is oriented towards a central portion of the heating element 16. For example, the axis A passes through the center of the heating element 16.

[0054] For example, the axis A forms, with the longitudinal axis X, an angle between 0 and 75°, preferably between 5 and 60°, and even more preferably between 10 and 45°.

[0055] As shown in Figures 2 and 3, the end piece 20 comprises, in its lower part 20B, at least one air outlet orifice.

[0056] More particularly, the side wall 19 comprises, in the lower part 20B, at least one air outlet orifice, and preferably a plurality of air outlet orifices, called first air outlet orifices 24.

[0057] In the example described, each first air outlet orifice 24 has a circular shape. However, as a variant, the first air outlet orifices 24 could have other conceivable shapes, for example oblong, rectangular, tri angular, or other. Furthermore, the first air outlet orifices 24 do not necessarily all have the same shape.

[0058] Advantageously, the first air outlet orifices 24 are distributed circumferentially over the entire periphery of the side wall 19. Thus, air is injected, through these air outlet orifices 24, in all directions, which allows it to arrive in a substantially homogeneous manner on the heating element 16.

[0059] Preferably, the first air outlet orifices 24 are aligned circumferentially, in several rows superimposed in the direction of the axis A, for example, in the example described, in three rows.

[0060] For example, in each row, the distance between two adjacent first air outlet orifices 24 is less than the diameter of each of these two first air outlet orifices 24.

[0061] According to the embodiment described, the side wall 19 has, at least in the lower part 20B, a generally frustoconical shape. Thus, the first air outlet orifices 24 are oriented in a direction forming a non-right angle with the axis A.

[0062] It will be noted that the angle of the cone is preferably less than 80°.

[0063] It is thus possible to envisage an extra-flat cone with an angle of 80° relative to the axis A. In this case, the axis of the first outlet orifices 24 is 10° relative to the axis A.

[0064] According to a variant not shown, the lower part 20B could be cylindrical, in which case the axis of the first outlet orifices 24 is 90° relative to the axis A.

[0065] Advantageously, the tip 20 also comprises a bottom wall 26, provided at a distal end of the tip 20.

[0066] In the embodiment described, the end piece 20 comprises at least one air outlet orifice provided in said bottom wall 26, called second air outlet orifice 28. As a variant, the bottom wall 26 could not comprise an orifice.

[0067] In the example described, the bottom wall 26 comprises two second air outlet orifices 28, preferably arranged radially close to an external edge of the bottom wall 26.

[0068] For example, one of the second air outlet orifices 28 is delimited by a straight edge and a curved edge whose ends are connected to those of the straight edge.

[0069] For example, one of the second air outlet orifices 28 is delimited by two parallel curved long edges, connected at their ends by two short edges.

[0070] Other shapes of second air outlet orifices 28 may also be provided, for example with a circular, rectangular, triangular, oblong edge, or any conceivable shape.

[0071] It should be noted that the end piece 20 has an air inlet opening 30, visible on [Fig. 3], connected to the nozzle 18. This air inlet opening 30 has an air inlet section, and each air outlet orifice 24, 28 has an air outlet section of its own, such that the sum of the surfaces of the air outlet sections is between 20% and 200% of the surface of the air inlet section.

[0072] Preferably, the sum of the surfaces of the air outlet sections is greater than the surface of the air inlet section. Thus, the nozzle 20 does not imply a counter-pressure opposing the injected air flow.

[0073] Advantageously, in the upper part 20A, the end piece 20 has an internal conduit widening from the air inlet opening 30 to the lower part 20B.

[0074] Preferably, the end piece 20 comprises a flange 32 for fixing this end piece 20 to the nozzle 18.

[0075] It will be noted that the tip 20 is for example manufactured by the following manufacturing method.

[0076] The manufacturing method comprises the production of the flange 32 on the one hand, and of a tube on the other hand.

[0077] The method then comprises deforming the tube, to form the collar 22.

[0078] The tube is also preferably deformed, in its lower part, to form the lower part 20B, for example in a truncated cone shape.

[0079] The method then comprises drilling the first air outlet orifices 24.

[0080] Finally, the method comprises assembling the flange 32 with the tube, to form the end piece 20. The assembly is for example carried out by welding.

[0081] It will be noted that the method advantageously comprises the production of the bottom wall 26, preferably comprising the second outlet orifice(s) 28, and the assembly of this bottom wall 26 with the tube at its end, for example by welding.

[0082] The end piece 20 thus formed is attached to the purification device 10, more particularly in the opening 21 of the inlet part 12B, so that the collar 22 comes to rest against the edge of the opening 21. The collar 22 is then preferably welded to this edge of the opening 21. The collar 22 makes it possible to ensure the assembly by welding of the end piece 20 on the inlet part 12B while avoiding the projection of solder particles inside the purification device.

[0083] Alternatively, the end piece 20 could be produced by casting, or any other conceivable method.

[0084] It appears that the nozzle 20 according to the invention makes it possible to diffuse the air homogeneously towards the heating element 16. The air arriving in the nozzle 20 is distributed between the plurality of outlet orifices, which creates turbulence in the air flow and makes it possible to obtain good homogeneity and good velocity of the air on the heating element. 16.

[0085] It will be noted that the invention is not limited to the embodiment previously described, but could have various complementary variants.

Claims

Claims

1. Device (10) for purifying exhaust gases, in particular for a heat engine, comprising a housing (12) in which an exhaust gas is intended to circulate, a purification member (14) housed in the housing, a heating element (16) arranged close to the purification member (14), and an air inlet nozzle (18) opening into the housing (12), characterized in that: - the nozzle (18) is equipped with a nozzle (20), the nozzle (20) comprising a side wall (19) of general revolution shape, at least one first air outlet orifice (24) being provided in said side wall (19), - the nozzle (20) comprises a bottom wall (26), provided at a distal end of the nozzle (20), and - the nozzle (20) comprises at least one second air outlet orifice (28) arranged in the back wall (26).

2. Purification device (10) according to claim 1, wherein each second air outlet orifice (28) of the bottom wall (26) is chosen from: - an air outlet orifice delimited by a straight edge and a curved edge whose ends are connected to those of the straight edge, and / or - an air outlet orifice delimited by two parallel curved long edges, connected at their ends by two short edges, and / or - a circular air outlet orifice.

3. Purification device (10) according to any one of the preceding claims, in which the side wall (19) of the end piece (20) has a generally frustoconical shape on at least a lower part (20B) of this end piece (20).

4. A purification device (10) according to any preceding claim, wherein the nozzle (20) comprises an upper portion (20A) and a lower portion (20B) separated by a collar (22).

5. Purification device (10) according to claim 4, in which the side wall (19) of the nozzle (20) has, in the lower part (20B), an inner surface (19A) of general shape of revolution around an axis (A), the collar (22) extending in a plane forming a non-right angle with respect to the axis (A).

6. A purification device (10) according to claim 4 or 5, wherein the nozzle (20) comprises, in the upper part (20A), an air inlet opening (30), and a conduit widening from the air inlet opening (30) to the lower part (20B).

7. Purification device (10) according to any one of the preceding claims, wherein the nozzle (20) comprises an air inlet opening (30), having an air inlet section, each air outlet orifice (24, 28) having an air outlet section, such that the sum of the surfaces of the air outlet sections (24, 28) is between 20% and 200% of the surface of the air inlet section, preferably greater than 100%.

8. A purification device (10) according to any preceding claim, wherein the air inlet nozzle (18) is directed towards the heating element (16).

9. Purification device (10) according to any one of the preceding claims, comprising only a single air inlet nozzle (18).

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