Patent Publication Number: US-2023138976-A1

Title: Exhaust gas purification device with improved air inlet nozzle

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a U.S. non-provisional application claiming the benefit of French Application No. 21 11668, filed on Nov. 3, 2021, which is incorporated herein by reference in its entirety. 
     TECHNICAL FIELD 
     The present disclosure relates to the field of exhaust gas purification devices, in particular for an internal combustion engine. Such a purification device is intended for being arranged in the exhaust line of the internal combustion engine. 
     BACKGROUND 
     The internal combustion engine is e.g. fitted to a vehicle, in particular a motor vehicle, a public transport vehicle or a freight transport vehicle, a marine vehicle, or any other conceivable vehicle. The internal combustion engine can also equip a fixed installation. 
     Exhaust lines of vehicles equipped with internal combustion engines usually include catalytic purification components, e.g. for converting NO x , CO and hydrocarbons into N 2 , CO 2  and H 2 O. Such components are generally effective only when the catalytic material is at a temperature above a predefined temperature threshold. 
     To this end, purification devices have been developed comprising a heating element mounted opposite the upstream face of a purification component, so as to accelerate the heating of the purification component when the vehicle is started. 
     Thus, an exhaust gas purification device is already known from the prior art, in particular for an internal combustion engine, which includes a casing extending along a longitudinal direction, a purification component housed in the casing, and a heating element arranged near the purification component. 
     In order to improve such a purification device, it is known how to arrange an air inlet nozzle opening into the casing, blowing air into the casing, in particular in order to avoid overheating of the heating element. 
     SUMMARY 
     The subject disclosure provides an improved purification device. 
     To this end, the subject matter of the disclosure is in particular a purification device for exhaust gases, in particular for an internal combustion engine, comprising a casing wherein an exhaust gas is intended to flow, a purification component housed in the casing, a heating element arranged in the vicinity of the purification component, and an air inlet nozzle opening into the casing. The air inlet nozzle is equipped with an end-piece, the end-piece including a lateral wall with a general shape of revolution, and at least a first air outlet port being formed in the lateral wall. 
     The end-piece, arranged at the end of an air inlet nozzle, is used for diffusing the air so as to spray the heating element as homogeneously as possible. In this way it is possible both to cool the heating element, and also to diffuse the heat from the heating element toward the purification component in the most homogeneous way possible. Due to the homogeneous diffusion, the purification component does not have any overheated point. As a result, the lifetime of the purification component is increased. Moreover, such homogeneous diffusion makes it possible to increase the maximum acceptable power of the heating element. Thus, the above advantageously results in a reduced catalysis initiation time. 
     The end-piece according to the disclosure can further include one or a plurality of the following features, taken individually or according to all technically conceivable combinations.
         The end-piece has a bottom wall, provided at a distal end of the end-piece.   The end-piece has at least one second air outlet port provided in the bottom wall.   Every second air outlet port of the bottom wall is chosen from: an air outlet port delimited by a straight edge and a curved edge, the ends of which are connected to the ends of the straight edge, and/or an air outlet defined by two parallel long, curved edges, connected at the ends thereof by two short edges, and/or a circular air outlet.   The lateral wall of the end-piece has a generally frustoconical shape on at least a lower part of this end-piece.   The end-piece has an upper part and a lower part separated by a collar.   The lateral wall of the end-piece has, in the lower part, an inner surface with a general shape of revolution about an axis, the collar extending in a plane forming a non-right angle with respect to the axis.   The end-piece comprises, in the upper part, an air inlet opening, and a duct widening from the air inlet opening to the lower part.   The end-piece comprises an air inlet opening, an air inlet cross-section, every air outlet opening having an air outlet cross-section, such that the sum of the surface areas of the air outlet cross-sections is comprised between 20% and 200% of the surface area of the air inlet cross-section, preferentially greater than 100%.   The air inlet nozzle is oriented toward the heating element.   The purification device has only one air inlet nozzle.       

    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Different aspects and advantages of the disclosure will appear upon reading the following description, given only as an example, and making reference to the annexed figures, amongst which: 
         FIG.  1    is a schematic view of a purification system according to an example of embodiment of the disclosure; 
         FIG.  2    is a perspective view of an end-piece of an air injection nozzle of the purification device shown in  FIG.  1   ; and 
         FIG.  3    is an axial section view of the end-piece shown in  FIG.  2   . 
     
    
    
     DETAILED DESCRIPTION 
       FIG.  1    shows a purification device  10  according to an example of embodiment of the disclosure, intended for equipping an exhaust line of an internal combustion engine. 
     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 depending on the direction of flow of the exhaust gases in the exhaust line. 
     The purification device  10  includes a casing  12  extending along a longitudinal direction X and delimiting a housing. In one example, the casing  12  is made of a metallic material. 
     The casing  12  includes a central part  12 A, an inlet part  12 B, and an outlet part  12 C. 
     The inlet part  12 B closes the housing on the upstream side, and the outlet part  12 C closes the housing on the downstream side. 
     The inlet part  12 B has a shape widening from an inlet pipe  13  of the upstream section to as far as the central part  12 A. The inlet part  12 B has a shape, e.g. a general frustoconical shape, or any shape which widens. 
     The purification device  10  includes a purification component  14  housed in the casing  12  so that the exhaust gases circulating in the casing  12  flow through the purification component  14 . The purification device  14  is an exhaust gas after-treatment component, e.g. a three-way catalyst, a diesel oxidation catalyst, an SCR catalyst, or is of any other suitable type. The purification component  14  preferentially has a general shape of revolution about an axis parallel to the longitudinal direction X. 
     Conventionally, the purification device  10  includes a heating device, comprising a heating element  16 , arranged close to the purification device  14 , preferentially upstream of the purification component  14 . 
     The heating element  16  is housed in the casing  12 . The heating element  16  is intended for preheating the purification device, in particular at the ignition of the engine or before the ignition. 
     Advantageously, the heating element  16  has a general shape of revolution defined about an axis parallel to the longitudinal direction X. 
     The heating element  16  is permeable to gas and, in particular, intended for letting through gases flowing along the longitudinal direction X (in particular exhaust gases, and air as will be subsequently described), so that the gases are heated when flowing through the heating element  16 . 
     Preferentially, the heating element  16  comprises a metal grid. In a variant, the heating element  16  can be made of a metal foam, or by any other suitable heating element, such as a honeycomb body. More particularly, the heating element  16  can be any resistive element suitable for transforming an electric current into heat. 
     The heating element  16  extends over the entire passage section of the casing  12 , so that the gases flowing through the casing  12  necessarily flow across the heating element  16 . The gases are thus heated uniformly. 
     Conventionally, the heating element  16  includes at least one, preferentially two electric terminals, through which the heating element  16  is intended to be electrically powered. For this purpose, each of these electric terminals is intended for being connected to a respective electrode. 
     The purification device  10  according to the disclosure includes at least one air injection nozzle  18  intended for injecting air into the housing. Preferentially the purification device  10  includes only one injection nozzle  18 . 
     The air blown through the injection nozzle  18  makes it possible in particular to diffuse heat energy during the preheating of the purification component  14  by the heating element  16 . 
     Advantageously, the injection nozzle  18  is arranged for running through the inlet part  12 B of the casing  12 . 
     The injection nozzle  18  is oriented along the direction of the heating element  16 , i.e. the air flow injected through the injection nozzle  18  has a component, along the longitudinal axis X, oriented along the same direction as the direction of flow of an exhaust gas through the casing  12 , from upstream to downstream. The fact that the nozzle  18  is oriented so as to blow air in the same direction as the exhaust gas flow makes it possible to reduce the impact of the air flow on the circulation of the exhaust gas, and not to generate back pressure nor thermomechanical stresses on the nozzle  18 . This situation occurs in particular for the passive phases of the heating element  16 , i.e. when the engine is in normal operation, and is all the more true for the phases of full engine load. The purpose of such 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 component  14 . 
     The injection nozzle  18  includes an end-piece  20  intended for optimizing the diffusion of air toward the heating element  16 . 
     The end-piece  20 , shown in greater detail in  FIGS.  2  and  3   , includes a lateral wall  19  with a general shape of revolution. 
     The end-piece  20  extends along an axis A. In the example described, the lateral wall  19  has a general shape of revolution about the axis A. 
     The end-piece  20  includes an upper part  20 A, intended for being arranged outside the casing  12 , and a lower part  20 B, intended for extending inside the casing  12 . Thus, the end-piece  20  runs through an opening  21  provided in the inlet part  12 B. 
     Advantageously, the end-piece  20  includes a collar  22  separating the upper  20 A and lower  20 B parts. The collar  22  is intended to abut against the edge of the opening  21 . The collar  22  provides the joining by welding of the end-piece  20  onto the inlet part  12 B, preventing the projection of welding particles inside the purification device. 
     The collar  22  is preferentially inclined with respect to the axis A, i.e. the collar extends in a plane forming a non-right angle with the axis A. The inclination of the collar  22  thus imposes the orientation of the end-piece  20  inside the casing  12 , i.e. the orientation of the lower part  20 B. A person skilled in the art designing the end-piece  20  would easily be able to choose the inclination of the collar  22  according to the desired orientation for the lower part  20 B. 
     More particularly, in the lower part  20 B, the lateral wall  19  has an inner surface  19 A and an outer surface  19 B. In the example described, the inner surface  19 A and the outer surface  19 B are concentric, both having a general shape of revolution defined about the axis A. However, in a variant, only the inner surface  19 A has a general shape of revolution defined about the axis A, the shape of the outer surface  19 B being less important for the diffusion of air. 
     In a preferred embodiment, the end-piece  20  is oriented toward a central part of the heating element  16 . The axis A passes e.g. through the center of the heating element  16 . 
     The axis A forms with the longitudinal axis X an angle within a range, e.g. between 0 and 75°, preferentially between 5 and 60°, and further preferentially between 10 and 45°. 
     As shown in  FIGS.  2  and  3   , the end-piece  20  includes, in the lower part  20 B thereof, at least one air outlet port. 
     More particularly, the lateral wall  19  includes, in the lower part  20 B, at least one air outlet port, and preferentially a plurality of air outlet ports, called first air outlet ports  24 . 
     In the example described, each first air outlet port  24  has a circular shape. However, in a variant, the first air outlet ports  24  could have other possible shapes, e.g. oblong, rectangular, triangular or other. Moreover, the first air outlet ports  24  do not necessarily all have the same shape. 
     Advantageously, the first air outlet ports  24  are distributed circumferentially throughout the entire periphery of the lateral wall  19 . Thus, air is injected, through the air outlet ports  24 , in all directions, which allows the air to arrive substantially homogeneously onto the heating element  16 . 
     Preferentially, the first air outlet ports  24  are aligned circumferentially, in a plurality of rows superposed along the direction of the axis A, e.g., in the example described, in three rows. 
     In every row e.g. the distance between two adjacent first air outlet ports  24  is less than the diameter of each of the two first air outlet ports  24 . 
     According to the embodiment described, the lateral wall  19  has, at least in the lower part  20 B, a general frustoconical shape. Thus, the first air outlet ports  24  are oriented along a direction forming a non-right angle with the axis A. 
     It should be noted that the angle of a cone formed by the frustoconical shape is preferentially less than 80°. 
     It is thus possible to envisage an extra flat cone with an angle of 80° with respect to the axis A. In such case, the axis of the first outlet ports  24  is 10° with respect to axis A. 
     According to a variant (not shown), the lower part  20 B could be cylindrical, in which case the axis of the first outlet ports  24  is 90° with respect to the axis A. 
     Advantageously, the end-piece  20  includes in addition, a bottom wall  26 , provided at a distal end of the end-piece  20 . 
     In the embodiment described, the end-piece  20  comprises at least one air outlet port formed in said bottom wall  26 , called the second air outlet port  28 . In a variant, the bottom wall  26  cannot include a port. 
     In the example described, the bottom wall  26  includes two second air outlet ports  28 , preferentially arranged radially close to an outer edge of the bottom wall  26 . 
     One of the second air outlet ports  28  is, for example, bounded by a straight edge and a curved edge the ends of which are connected to the ends of the straight edge. 
     One of the second air outlet ports  28  is, for example, delimited by two parallel long, curved edges, connected at the ends thereof by two short edges. 
     It is also possible to provide the second air outlet ports  28  with other forms, e.g. with a circular, rectangular, triangular, oblong edge, or any conceivable form. 
     It should be noted that the end-piece  20  includes an air inlet opening  30 , visible in  FIG.  3   , connected to the nozzle  18 . The air inlet opening  30  has an air inlet cross-section, and each air outlet opening  24 ,  28  has its own air outlet cross-section, such that the sum of the surface areas of the air outlet cross-sections is comprised between 20% and 200% of the surface area of the air inlet cross-section. 
     Preferentially, the sum of the surface areas of the air outlet cross-sections is greater than the surface area of the air inlet cross-section. Thus, the end-piece  20  does not imply a back pressure resisting the flow of injected air. 
     Advantageously, in the upper part  20 A, the end-piece  20  has an internal duct widening from the air inlet opening  30  to as far as the lower part  20 B. 
     Preferentially, the end-piece  20  includes a flange  32  for fastening the end-piece  20  to the nozzle  18 . 
     It should be noted that the end-piece  20  is, for example, manufactured by the following manufacturing method. 
     The manufacturing method includes the production of the flange  32  and of a tube. 
     The method then includes the deformation of the tube, so as to form the collar  22 . 
     The tube is also preferentially deformed, in the lower part thereof, so as to form the lower part  20 B with a shape, e.g. in the form with a frustoconical shape. 
     The method then includes the drilling of the first air outlet ports  24 . 
     Finally, the method includes the joining of the flange  32  with the tube, for forming the end-piece  20 . The joining is performed, for example, by welding. 
     It should be noted that the method advantageously includes the production of the bottom wall  26 , preferentially comprising the second outlet port or ports  28 , and the joining of the bottom wall  26  with the tube at the end thereof by welding, for example. 
     The end-piece  20  thus formed is directly mounted onto the purification device  10 , more particularly in the opening  21  of the inlet part  12 B, so that the collar  22  rests against the edge of the opening  21 . The collar  22  is then preferentially welded to said edge of the opening  21 . The collar  22  provides the joining by welding of the end-piece  20  on the inlet part  12 B, preventing the projection of welding particles inside the purification device. 
     In a variant, the end-piece  20  could be produced by casting, or any other conceivable method. 
     It appears that the end-piece  20  according to the disclosure can be used for diffusing the air homogeneously toward the heating element  16 . The air arriving in the end-piece  20  is distributed between the plurality of outlet ports, which creates turbulence in the air flow and makes it possible to obtain a good homogeneity and a good velocity of the air on the heating element  16 . 
     It should be noted that the disclosure is not limited to the embodiment described above, but could have various supplementary variants.