Exhaust gas burner and exhaust gas aftertreatment system

Abstract

The invention relates to an exhaust gas burner (10) for an exhaust gas aftertreatment system (1) of an internal combustion engine (2), comprising a housing (22) in which a combustion chamber (11) is formed, in which combustion chamber a mixture of an oxygen-containing gas and fuel can be burned to form a heating gas, wherein at least one injection valve (12) for injecting the fuel into the combustion chamber (11) and an ignition device (14) for igniting the injected fuel (15) are arranged on the housing (22), and wherein the combustion chamber (11) has a gas inlet (13) for the gas and a heating gas outlet (15) for the heating gas, wherein the heating gas outlet (15) is formed by a tubular heating gas guide (26) which projects with the heating gas outlet (15) from the housing (22), and comprising a fastening flange (24), associated with the heating gas outlet (15), for connecting the exhaust gas burner (10) to an inlet pipe (25) of the exhaust gas aftertreatment system (1). According to the invention, the housing (22) has the fastening flange (24) at the end associated with the heating gas outlet (15) and is also radially spaced apart from the heating gas guide (26).

Description

[0001] Description

[0002] title

[0003] Exhaust gas burner and exhaust gas aftertreatment system

[0004] The present invention relates to an exhaust gas burner for an exhaust gas aftertreatment system of an internal combustion engine, comprising a housing in which a combustion chamber is formed in which a mixture of an oxygen-containing gas and fuel can be combusted to form a heating gas, wherein at least one injection valve for injecting the fuel into the combustion chamber and an ignition device for igniting the injected fuel are arranged on the combustion chamber, and wherein the combustion chamber has a gas inlet for the gas and a heating gas outlet for the heating gas, wherein the heating gas outlet is formed by a tubular heating gas guide which projects from the housing with the heating gas outlet, and with a mounting flange associated with the heating gas outlet for connecting the exhaust gas burner to an inlet pipe of the exhaust gas aftertreatment system.

[0005] Furthermore, the invention relates to an exhaust aftertreatment system for an internal combustion engine of a motor vehicle, comprising at least one exhaust aftertreatment device, in particular a catalyst or filter, and an exhaust burner flow-technically positioned upstream of the exhaust aftertreatment device.

[0006] State of the art

[0007] Exhaust gas burners of the type mentioned above are already known from the prior art. For example, German patent application DE 19 504208 A1 discloses an exhaust gas burner that is fluidically integrated upstream of a catalyst in an exhaust aftertreatment system. The exhaust gas burner has a combustion chamber into which air and fuel are supplied and combusted by means of an ignition device, in order to be subsequently added or mixed with the exhaust gas stream upstream of the catalyst. This ensures that the catalyst is heated to an advantageous operating temperature particularly quickly.

[0008] It is also known that the flue gas outlet is formed by a tubular flue gas channel and projects axially from the housing. A flange connection is provided for connecting the exhaust gas burner or for connecting the exhaust gas aftertreatment system, which is installed as intended. This flange has a mounting flange associated with the flue gas outlet, which can be securely and tightly connected to a counter-mounting flange of an inlet pipe of the exhaust gas aftertreatment system.

[0009] Disclosure of the invention

[0010] The exhaust gas burner according to the invention, with the features of claim 1, has the advantage that functional separation is ensured, whereby the flue gas is thermally separated, at least substantially, from the connection between the exhaust gas burner and the exhaust gas aftertreatment system. For this purpose, the invention provides that the housing, at its end associated with the flue gas outlet, has a mounting flange on the one hand and is radially spaced from the flue gas path on the other. This results in the mounting flange being thermally separated from the flue gas outlet. The distance, or radial distance, between the mounting flange and the flue gas outlet ensures that direct heat transfer from the flue gas path to the mounting flange is prevented. This results in the connection point to the exhaust gas aftertreatment system being subjected to less thermal stress.This is particularly advantageous when the mounting flange is welded to the counter-mounting flange of the exhaust aftertreatment system. Preferably, the mounting flange is formed integrally with the housing or is formed by the housing, with the mounting flange being located particularly downstream of the combustion chamber. According to a preferred embodiment of the invention, the mounting flange is arranged axially spaced from the flue gas outlet. This further optimizes the thermal separation, as the mounting flange is then located even further away from the flue gas exiting the flue gas outlet. It is particularly advantageous to arrange the mounting flange axially spaced from the flue gas outlet against the flow direction, so that the flue gas exits the flue gas duct downstream of the mounting flange.

[0011] Preferably, the flue gas guide has at least one spacer on its section located inside the housing, which rests against an inner surface of the housing. The spacer ensures that the desired radial distance between the housing and the flue gas guide is maintained permanently. Optionally, the spacer also serves to fasten the flue gas guide to the housing. For example, the spacer can be bonded to the housing by a material-fit and / or form-fit connection. In particular, the spacer can be integrally formed with the flue gas guide or permanently bonded to it by a material-fit and / or form-fit connection.

[0012] Furthermore, the section of the flue gas guide with the spacer preferably has several spacers arranged evenly distributed around the circumference of the flue gas guide. This ensures secure support of the flue gas guide within the housing. In particular, this securely supports the flue gas guide against the housing in all directions around its circumference, thus preventing any undesired radial displacement of the flue gas guide within the housing.

[0013] Alternatively, the section preferably features a spacer extending over the entire circumference of the flue gas duct. This spacer is annular in shape and ensures a secure arrangement of the flue gas duct within the housing. Furthermore, the circumferentially annular spacer enables and preferably provides a secure fit and thus advantageous attachment of the flue gas duct to the housing. In particular, the annular spacer is connected to the housing and / or the flue gas duct, as described above for the at least one spacer.

[0014] According to a preferred embodiment of the invention, the flue gas guide forms a baffle within the housing, spaced apart from the flue gas outlet, particularly at the end furthest from the flue gas outlet, which radially limits the combustion chamber in certain areas. This baffle forms a so-called flame wall, which, among other things, prevents the combustion taking place in the combustion chamber from propagating unhindered towards the exhaust aftertreatment system. Furthermore, the baffle, which is located particularly radially on the outer side of the housing, prevents unburned fuel remaining on the inside of the combustion chamber from being transported unburned into the exhaust aftertreatment system by the exhaust gas flow.

[0015] Preferably, the orifice plate is V-shaped in longitudinal section and has a cross-section, in particular diameter, that increases towards the flue gas outlet. Viewed in the direction of flow, the orifice plate thus forms a flow chamber downstream of the orifice plate, which is essentially separated from the combustion chamber by the orifice plate.

[0016] Preferably, the flue gas duct, either downstream of or spaced apart from the orifice plate, features a funnel section with a diameter reduction towards the flue gas outlet. Downstream of the orifice plate, the diameter of the flue gas duct is thus reduced again, creating a space between the funnel section and the orifice plate that offers advantages such as acoustic and fluid dynamics benefits. The funnel section, in particular, concentrates the flue gas and advantageously directs it to the exhaust gas aftertreatment system.

[0017] Preferably, the orifice and the funnel section together form at least one spacer extending over the entire circumference of the flue gas passage. In this respect, the orifice and funnel section together form the circumferentially extending annular spacer. Preferably, at least one bypass opening is formed in the funnel section. Through the bypass opening, the flue gas can thus escape from the flue gas passage past the flue gas outlet. Because the bypass opening is formed in the funnel section, it is ensured that the flue gas flow guided by the funnel shape also reaches the bypass opening. The flue gas then flows through the bypass opening into the area between the flue gas passage and the housing. In this respect, a partial flue gas flow is permitted, which exits the flue gas passage, in particular, upstream of the flange.By restricting the partial flow of the flue gas to at least one, and in particular only one, bypass opening, the aforementioned advantage of thermal decoupling of the mounting flange from the flue gas path is maintained. This partial flow of flue gas offers the advantage that the flue gas can be directed specifically to a lambda probe downstream of the exhaust gas burner, allowing the mixture ratio of the flue gas to be advantageously measured or determined using the lambda probe. In intended use, the bypass opening is preferably positioned such that the partial flow of the flue gas is directed towards the lambda probe.

[0018] Preferably, at least one air guide element is associated with the bypass opening, which is particularly integral with the flue gas duct. The air guide element advantageously directs the flue gas partial flow in the desired direction. In particular, the air guide element is designed as a stamped and bent part in the form of a bent tongue, so that the manufacturing effort for the bypass opening and air guide element is minimal.

[0019] According to an alternative embodiment to the orifice and funnel section, the flue gas guide has a constant cross-section along its entire length. This reduces the manufacturing effort for the exhaust gas burner, particularly the flue gas guide, because it eliminates the need for more complex internal high-pressure forming or a multi-part construction of the flue gas guide with an orifice and funnel section. Furthermore, the constant cross-section offers advantages in terms of the thermal load capacity of the flue gas guide. According to an alternative embodiment, the flue gas guide preferably has a cross-section that either widens or narrows only towards the flue gas outlet. Thus, the flue gas guide either continuously widens or narrows in diameter in the direction of flow. This also results in the aforementioned manufacturing advantages.For example, the heating gas routing is designed in a conical shape with a slope in the longitudinal direction or in a diffuser-like shape with a curvature in the longitudinal direction.

[0020] The exhaust gas aftertreatment system according to the invention, with the features of claim 14, is characterized in that the exhaust gas burner is designed according to the invention. This results in the advantages already mentioned above. Further advantages and preferred features and combinations of features will become apparent from the foregoing description.

[0021] In particular, at least one sensor, especially a lambda sensor, is arranged between the exhaust aftertreatment device and the exhaust burner, and the bypass opening is associated with the sensor. This results in the advantages already mentioned above.

[0022] The invention will now be explained in more detail with reference to the drawing.

[0023] This shows

[0024] Figure 1 shows an advantageous exhaust aftertreatment system in a simplified representation.

[0025] Figure 2 shows an enlarged view of an exhaust gas burner of the exhaust gas aftertreatment system.

[0026] Figures 3A to D show different embodiments of the exhaust gas burner from Figure 2.

[0027] Figures 4A to H show further embodiments of the exhaust gas burner, Figure 5 shows a further embodiment of the exhaust gas burner,

[0028] Figures 6A to D show further embodiments of the exhaust gas burner,

[0029] Figure 7 shows an embodiment of a heating gas routing system of the

[0030] exhaust burner

[0031] Figure 8 shows a schematic representation of the heating gas flow.

[0032] Figure 9 shows another embodiment of the exhaust gas burner with a lambda probe.

[0033] Figures 10A to D show further embodiments of a flue gas routing system for the exhaust gas burner.

[0034] Figure 1 shows a simplified representation of an advantageous exhaust aftertreatment system 1 for an internal combustion engine 2 of a motor vehicle, which in this case is designed as a reciprocating piston engine. The internal combustion engine 2 is associated with a fresh air intake tract 3 and an exhaust exhaust tract 4. From the exhaust valves of the internal combustion engine 2, an exhaust pipe 5 of the exhaust exhaust tract 4 leads to several exhaust aftertreatment devices 6, 7, and 8 of the exhaust aftertreatment system 1. In this case, viewed in the direction of flow, the first exhaust aftertreatment device 6 is a three-way catalytic converter, the second exhaust aftertreatment device 7 is a second three-way catalytic converter, and the third exhaust aftertreatment device 8 is a particulate filter. The exhaust aftertreatment devices 6, 7, and 8 are sequentially supplied with exhaust gas from the internal combustion engine and serve to reduce pollutant emissions and particulate matter in the exhaust gas.To ensure that the exhaust aftertreatment devices 6, 7, 8 reach their optimal operating temperature as quickly as possible, particularly after a cold start of the internal combustion engine 2, a heating device 9 with an exhaust gas burner 10 of the exhaust aftertreatment system 1 is also assigned to the exhaust tract 4. The exhaust gas burner 10 has a combustion chamber 11 to which fuel can be supplied via an injection valve 12 and oxygen-containing gas, in this case air, via a gas inlet 13, for example by means of a gas guide device, in order to be ignited and burned in the combustion chamber by means of an ignition device 14. The combusted fuel / air mixture is fed into the exhaust tract 4 upstream of the first catalyst 6 via an outlet opening 15 of the exhaust gas burner 10, so that the heated gas mixture already increases the operating temperature of the exhaust aftertreatment devices 6, 7, 8 before the internal combustion engine 2 itself has reached its required operating temperature.

[0035] An adjustable valve assembly 16 is connected upstream of the exhaust gas burner 10, by means of which the supplied airflow can be adjusted. An air pump or air supply device 17 is advantageously arranged upstream of the valve assembly 16, by means of which fresh air is drawn in and conveyed towards the valve assembly 16. An air mass meter 18 and an air filter 19 are also connected upstream of the air supply device 17.

[0036] A control unit 20 of the heating system controls and operates the air mass meter 18, the air pump 17, the valve assembly 16, and the exhaust gas burner 10 to generate the desired amount of hot gas resulting from the combustion of the air-fuel mixture. This hot gas is supplied to the exhaust tract 4 to heat the exhaust aftertreatment devices 6, 7, and 8. The control unit 20 is in communication with a control unit 21 of the internal combustion engine.

[0037] Figure 2 shows a simplified longitudinal section of the exhaust gas burner 10. The exhaust gas burner 10 has a housing 22 in which the combustion chamber 11 is formed. The aforementioned gas guide device, which, according to this embodiment, surrounds and preferably supports the injection valve 12, is not shown for clarity, nor is the ignition device 14. The housing 22 is essentially cylindrical, in particular circular cylindrical. At its end associated with the flue gas outlet 15, the housing 22 has a taper 23 in its longitudinal dimension. A mounting flange 24 is arranged or formed on the housing 22 at this tapered free end, which serves to connect the housing 22, and thus the exhaust gas burner 10, to an inlet pipe 25 of the exhaust gas aftertreatment system 4. Preferably, the mounting flange is formed integrally with the housing 22 of the exhaust gas burner 10.The inlet pipe 25 is, for example, the exhaust pipe 5 or an inlet pipe branching off from the exhaust pipe 5.

[0038] The flue gas outlet 15 itself is formed by a flue gas guide 26, which is essentially tubular and lies partially within the housing 22. According to the present embodiment, the flue gas guide 26 has an orifice 27 at its end located in the housing 22 or the combustion chamber 11, which radially limits the combustion chamber 11 in certain areas. The orifice 27 extends in an annular shape over the entire circumference of the flue gas guide 26 and rests against an inner surface 28 of the housing 22 on its outer side. In longitudinal section, the orifice 27 has a V-shaped longitudinal section that widens towards the flue gas outlet 15. Thus, the orifice 27 has an opening 38 from which the diameter of the orifice 27 initially widens until it reaches the inner surface 28 of the housing 22.Longitudinally spaced from the orifice 27, a funnel section 29 is formed in the flue gas duct 26, in which the diameter of the flue gas duct 26 decreases again towards the flue gas outlet 15, in this case back to the dimension of the opening 38. The diameter of the flue gas outlet 15 is thus also smaller than the diameter of the inlet pipe 25 and the housing 22 in the area of ​​the mounting flange 24. This creates a kind of chamber between the orifice 27 and the funnel section 29. Because the diameter of the orifice 27 widens to such an extent that the flue gas duct 26 reaches the inner surface 28 of the housing 22, the tubular flue gas duct 26, together with the funnel section 29 and the orifice 27, forms a spacer 30 extending over the entire circumference of the flue gas duct 26.The spacer 30 ensures that the flue gas outlet 15, located in the tapered section downstream of the funnel section 29, is spaced apart from the mounting flange 24. This radial distance x ensures thermal decoupling between the flue gas outlet and the mounting flange 24. The mounting flange 24, which is welded to a counter-mounting flange 31 of the inlet pipe 25 to connect the exhaust gas burner 10 to the exhaust gas aftertreatment system 4, is thus advantageously protected from the hot exhaust gases of the exhaust gas burner 11 exiting the flue gas outlet 15 downstream of the mounting flange. The mounting flange 24 is arranged axially offset from the flue gas outlet 15, opposite to the flow direction, and is radially spaced from it by means of the spacer 30.This ensures that the weld point between mounting flange 24 and mounting flange 31 is safely protected against material fatigue caused by heat.

[0039] Figures 3A to D show different embodiments of the exhaust gas burner 10, each in a simplified longitudinal section view. Elements known from the previously described embodiment are identified here and in the subsequent figures with the same reference numerals, so reference is made to the description above. The following discussion will focus primarily on the differences.

[0040] The embodiment shown in Figure 3A corresponds to the embodiment shown in Figure 2, except that the inlet pipe 25 is not shown. The orifice 27 forms a so-called flame wall 32, which, among other things, prevents liquid fuel located on the inside 28 of the housing 22 from entering the downstream exhaust aftertreatment tract through the hot gas outlet 15. Furthermore, the flame wall 32, or the orifice 27, prevents a flame generated by combustion in the combustion chamber 11 from traveling along the housing wall of the housing 22 to the mounting flange 24 and causing undesirable heating there.

[0041] In contrast, the embodiment shown in Figure 3B depicts a flue gas guide 26 that has a cross-section, in particular diameter, that is constant along its entire length. In this case, the flue gas guide 26 is circular. To ensure the radial distance between the flue gas outlet 15 and the housing or the mounting flange 24, the flue gas guide 26 has one or more spacers 30 on its section located inside the housing 22. These spacers are formed by radially projecting support elements 33. The support elements 33 are attached at one end to the flue gas guide 26 and at the other end rest against the inner surface 28 of the housing 22, and are preferably permanently connected to it, for example, by welding. In this embodiment as well, the spacers 30 advantageously ensure the radial distance x between the flue gas outlet 15 and the mounting flange 24.While in the previous embodiment the heating gas outlet 15 is located downstream of the mounting flange 24, according to the present embodiment of Figure 3B the heating gas outlet 15 is arranged or designed at the level of or only slightly upstream of the mounting flange 24.

[0042] The initial example in Figure 3C is characterized by a larger diameter for the flue gas channel 26 than in the embodiment shown in Figure 3B. In the embodiment shown in Figure 3D, the diameter of the flue gas channel 26 is even larger than in the preceding embodiments. This results in a gradual reduction of the radial distance between the flue gas outlet and the mounting flange 24 from the embodiments shown in Figure 3B to Figure 3D. However, a sufficient radial distance x is always maintained for thermal coupling. Optionally, in these and the following embodiments, only one spacer 30 is provided, extending over the entire circumference of the circular flue gas channel 26.

[0043] Figures 4A to H show further embodiments of the exhaust gas burner 10, each in a longitudinal section view. These are variants of the exhaust gas burner 10 according to the embodiment shown in Figure 3C.

[0044] The embodiment shown in Figure 4A differs from the preceding embodiment in that the spacer(s) 30 shown in the embodiment shown in Figure 3C, which extend radially in a plane perpendicular to the longitudinal extent of the flue gas channel 26, are now inclined to this plane. In the case of the example shown in Figure 4A, the spacers 30 form an angle of less than 90° to the flue gas channel 26, with the angle being upstream of the spacers 30.

[0045] According to the embodiment shown in Figure 4B, the spacer(s) 30 are inclined in opposite directions. In the embodiments shown in Figures 3B to D and 4A and B, the spacers are arranged at intervals from the inner end of the flue gas channel 26 in the housing 22. In contrast, the embodiment shown in Figure 4C shows the spacer(s) 30 being arranged directly at the end of the flue gas channel 26 of the housing 22 and inclined in one direction or the other, or aligned in the plane perpendicular to its longitudinal extent. Figure 4C shows the embodiment in which the spacer(s) 30 are aligned as in the embodiment shown in Figure 4B.

[0046] The embodiment shown in Figure 4D differs from the previous embodiment in that the hot gas guide 26 does not extend parallel to the longitudinal axis of the combustion chamber 11 and thus parallel to the flow direction of the exhaust gas burner 10, but is inclined at an angle to it.

[0047] The embodiment shown in Figure 4E differs from the embodiment shown in Figure 3C in particular in that the flue gas guide 26 projects axially from the housing 22 of the exhaust gas burner 10, so that an axial distance y from the flue gas outlet 15 to the mounting flange 24 is ensured, as already explained in relation to the embodiments shown in Figures 2 and 3A.

[0048] According to the embodiment shown in Figure 4F, the flue gas guide 26 has a curvature 37 at its downstream end section, by which the flue gas is directed in a desired direction. The embodiments shown in Figures 4G and 4H differ from the embodiment shown in Figure 3C, in particular, in that the spacer(s) 30 each have a radial outward curvature in their course, so that the respective spacer 30 is concave or convex in longitudinal section.

[0049] Figure 5 shows a further embodiment that differs from the previous ones in that the flue gas guide 26 extends significantly further out of the housing 22 in order to maximize the distance y between the flue gas outlet 15 and the mounting flange 24. This also provides air gap insulation between the flue gas guide 26 and the inlet pipe 25 of the exhaust gas aftertreatment system 1.

[0050] Figures 6A to 6D show further embodiments of the exhaust gas burner 10, which differ in the design of the flue gas guide 26. These embodiments have in common that the cross-section or diameter of the flue gas guide 26 either increases only (Figures 6A to C) or decreases only (Figure 6D) in the direction of the flue gas outlet. According to Figure 6A, the flue gas guide 26 is conical with a cross-section that widens in the direction of flow. According to the embodiment shown in Figure 6B, the flue gas guide 26 is diffuser-shaped with a widening cross-section, the cross-section widening due to a curvature along its length. In this embodiment, the outer wall of the flue gas guide 26 is curved outwards.According to the embodiment shown in Figure 6C, the flue gas guide 26 is also designed in a diffuser-like manner, whereby in this case the curvature of the outer wall in the longitudinal direction of the flue gas guide 26 is convexly curved towards the flue gas outlet, so that the diameter widening in the longitudinal direction decreases. The embodiment shown in Figure 6D is characterized in that the cross-section or diameter of the flue gas guide 26 decreases towards the flue gas outlet 15, and here the flue gas guide 26 is also conically shaped.

[0051] Figure 7 shows an optional further development of the flue gas guide 26, in which several rings are drawn, each showing the cross-sectional shape of the flue gas guide 26 at different points along its longitudinal extent. The rearmost ring shows the contour or cross-sectional shape of the flue gas outlet 15, and the foremost ring shows the cross-sectional shape of the inlet opening 38 of the flue gas guide 26. This further development is characterized by the fact that the cross-section changes along the longitudinal extent of the flue gas guide 26 from the inlet 38 to the flue gas outlet 25. Thus, according to the present embodiment shown in Figure 7, the cross-section at the inlet or opening 38 is circular, and the cross-section at the flue gas outlet 15 is oval. The cross-sectional shape is continuously changed or adapted from the opening 38 to the flue gas outlet 15.

[0052] Optionally, the cross-sectional area at the flue gas outlet 15 is at least as large, preferably larger, than the cross-sectional area at the opening 38. According to another initial example, the cross-sectional areas at the inlet and outlet are always the same size, regardless of their shape or contour.

[0053] Figure 8 shows another longitudinal section of the exhaust gas burner 10 in the area of ​​the flue gas outlet 15, where the flow behavior of the flue gas is simplified. In addition to the previously described thermomechanical improvement resulting from the functional separation between the mounting flange 24 and the flue gas guide 26, ensured by the radial distance x between the flue gas guide 26 and the mounting flange 24, a geometric diameter change also occurs at the flue gas outlet 15. This results in the simplified flow behavior shown in Figure 8. This, in turn, offers improved possibilities for the standardized integration of a lambda probe at the burner outlet.A key feature of the preferred lambda probe arrangement is that it is not located in the main mass flow of the flue gas, but rather in a peripheral region of the main flow where increased turbulence occurs, as shown in Figure 8. This significantly reduces the temperature input from the flue gas to the lambda probe compared to standard or previously known solutions. Therefore, despite the high flue gas temperatures, a lambda probe can be safely positioned at the burner outlet or flue gas outlet 15.

[0054] Figure 9 shows an embodiment in which a lambda probe 34 is arranged on the inlet pipe 25 close to the mounting flange 31, particularly in the area so close to the flue gas outlet 15 that it is not in the main flue gas flow, as described above. Optionally, the inlet pipe 25 is also an adapter pipe that can be inserted between the exhaust gas aftertreatment system 4 and the exhaust gas burner 10, and can be adapted to different boundary conditions, for example, to allow for an advantageous flue gas routing and / or arrangement of a lambda probe 34.

[0055] To enable improved integration of the lambda probe 34 into the heating gas flow without unintentionally increasing the temperature load on the lambda probe significantly, the heating gas guide 26 preferably has a bypass opening 35 in the funnel section 29, which leads into the space between the heating gas outlet 15 and the mounting flange 24, so that a partial heating gas flow is supplied to the lambda probe 34 through the bypass opening 35. The arrangement of the bypass opening 35 is selected such that the heating gas flow advantageously affects the lambda probe 34.

[0056] Figures 10A to D show different embodiments for the realization of the bypass opening 35, in which the end section of the hot gas guide 26 is shown with the hot gas guide 25.

[0057] According to the embodiment shown in Figure 10A, the bypass opening 35 is arranged as a simple bore or recess with a closed outer edge in the funnel section 29 or in the end section spaced apart from the hot gas outlet 15.

[0058] According to the embodiment shown in Figure 10B, the bypass opening 35 is designed as a V-shaped indentation or recess on its end face, such that the bypass opening 35 is open towards the heating gas outlet 15. 212262 POT

[0059] - 16 -

[0060] According to the embodiment shown in Figure 10C, an air guide element 36 is associated with the bypass opening 35. In this embodiment, the air guide element 36 is bent inwards and is arranged at the downstream end of the bypass opening 35 in the direction of flow of the heating gas, as indicated by the arrows in Figures 10A to D. Thus, the air guide element 36 lies within the heating gas flow inside the heating gas guide 26 and directs a portion of the heating gas flow from the heating gas guide 26 through the bypass opening 35. In particular, the air guide element 36 is designed as a stamped and bent part, such that it is cut out of the outer wall of the heating gas guide 26 and bent into the guide 26.

[0061] The embodiment shown in Figure 10D differs from the previous embodiment in that the air guide element 36 is not bent inwards, into the hot gas guide 26, but outwards.

Claims

Claims 1. Exhaust gas burner (10) for an exhaust gas aftertreatment system (1) of an internal combustion engine (2), comprising a housing (22) in which a combustion chamber (11) is formed in which a mixture of an oxygen-containing gas and fuel can be combusted to form a heating gas, wherein at least one injection valve (12) for injecting the fuel into the combustion chamber (11) and an ignition device (14) for igniting the injected fuel are arranged on the housing (22), and wherein the combustion chamber (11) has a gas inlet (13) for the gas and a heating gas outlet (15) for the heating gas, wherein the heating gas outlet (15) is formed by a tubular heating gas guide (26) which projects from the housing (22) along with the heating gas outlet (15), and with a mounting flange (24) associated with the heating gas outlet (15) for connecting the exhaust gas burner (10) to an inlet pipe (25) of the exhaust aftertreatment system (1), characterized in thatthat the housing (22) has, on the one hand, the mounting flange (24) at its end associated with the flue gas outlet (15) and, on the other hand, is radially spaced from the flue gas guide (26).

2. Exhaust gas burner according to claim 1, characterized in that the mounting flange (24) is arranged axially spaced from the hot gas outlet (15).

3. Exhaust gas burner according to claim 1, characterized in that the mounting flange (24) is arranged axially at the level of the hot gas outlet (15).

4. Exhaust gas burner according to one of the preceding claims, characterized in that the flue gas guide (26) has at least one spacer (30) on its section lying inside the housing (22), which rests against an inner side of the housing (22).

5. Exhaust gas burner according to one of the preceding claims, characterized in that the section has several spacers (30) arranged in a particularly uniform manner around the circumference of the flue gas guide (26).

6. Exhaust gas burner according to one of the preceding claims, characterized in that the section has a spacer (30) extending over the entire circumference of the flue gas guide (26).

7. Exhaust gas burner according to one of the preceding claims, characterized in that the heating gas guide (26) forms a baffle (27) within the housing, spaced apart from the heating gas outlet (15), which radially limits the combustion chamber (11) in certain areas.

8. Exhaust gas burner according to one of the preceding claims, characterized in that the aperture (27) is V-shaped in longitudinal section and has a diameter that increases in the direction of the hot gas outlet (15).

9. Exhaust gas burner according to one of the preceding claims, characterized in that the flue gas guide (26) has a funnel section (29) with a diameter reduction towards the flue gas outlet (15) following or spaced apart from the orifice (27).

10. Exhaust gas burner according to one of the preceding claims, characterized in that the aperture (27) and the funnel section (29) together form the one spacer (30) which extends over the entire circumference of the flue gas guide (26).

11. Exhaust gas burner according to one of the preceding claims, characterized in that at least one bypass opening (35) is formed in the funnel section (29).

12. Exhaust gas burner according to one of the preceding claims, characterized in that the bypass opening (35) has at least one air guide element - 19 - (36) is assigned, which is in particular formed in one piece with the flue gas guide (26).

13. Exhaust gas burner according to one of the preceding claims, characterized in that the flue gas guide (26) has a constant cross-section along its entire longitudinal extent or a cross-section that widens or narrows only in the direction of the flue gas outlet (15).

14. Exhaust aftertreatment system (1) for an internal combustion engine of a motor vehicle, comprising at least one exhaust aftertreatment device (6, 7, 8), in particular a catalyst or filter, and comprising an exhaust burner (10) flow-technically positioned upstream of the exhaust aftertreatment device (6, 7, 8), characterized in that the exhaust burner (10) is designed according to one of claims 1 to 13.

15. Exhaust aftertreatment system according to claim 14 in conjunction with claim 11 or 12, characterized in that at least one sensor, in particular a lambda sensor (34), is arranged between the exhaust aftertreatment device (6, 7, 8) and the exhaust burner (10), and that the bypass opening (35) is assigned to the lambda sensor (34).

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