Exhaust gas burner and exhaust gas aftertreatment system

Abstract

Sensor arrangement (28) for an exhaust gas burner (10) of an exhaust gas aftertreatment system (1), comprising at least one sensor (29), in particular a lambda probe, which can be arranged or is arranged downstream of a combustion chamber (11) of the exhaust gas burner (10). The sensor (29) is held on a pipe module (30), the pipe module (30) having a first connection connectable to the exhaust gas burner (10) and a second connection connectable to an outlet channel (27) or exhaust pipe (5) of an exhaust gas aftertreatment system (1).

Description

[0001] The present invention relates to an exhaust gas burner for an exhaust gas aftertreatment system, having a combustion chamber 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, wherein the combustion chamber has a guide device with a gas inlet for the gas and a heating gas outlet for the heating gas, wherein the heating gas outlet is assigned a sensor arrangement with at least one sensor, in particular a lambda probe, which can be arranged or is arranged downstream of a combustion chamber of the exhaust gas burner.

[0002] Furthermore, the present invention relates to an exhaust gas aftertreatment system with the above-mentioned exhaust gas burner. State of the art

[0003] Exhaust gas burners of the type mentioned above are already known from the prior art. For example, published patent application DE 195 04 208 A1 discloses an exhaust gas burner that is fluidically arranged upstream of a catalyst of an exhaust gas aftertreatment system. The exhaust gas burner has a combustion chamber to which air and fuel are supplied and combusted in the combustion chamber with the aid of an ignition device, and are subsequently added or mixed into the exhaust gas flow upstream of the catalyst. This ensures that the catalyst is heated particularly quickly to a favorable operating temperature. A similar solution is also proposed in published patent application DE 10 2009 053 379 A1. It is also provided that the fuel and the oxygen-containing gas are introduced coaxially into the combustion chamber.For this purpose, a guide device is assigned to the combustion chamber, which surrounds the injection valve at its end facing the combustion chamber along an axial section of the injection valve and thereby forms an air flow channel coaxial with the injection valve, the annular opening of which opens into the combustion chamber coaxial with the injection opening of the injection valve.

[0004] It is known to associate such exhaust gas burners with a sensor arrangement with a lambda probe, which can be used to monitor the proper operation of the exhaust gas burner. Lambda probes are typically used to monitor the ratio of combustion air to fuel in the heating gas or the residual oxygen content in the exhaust gas of an internal combustion engine, in order to monitor and adjust the proper operation of the internal combustion engine, in particular the proper combustion of the fuel. Since fuel is also burned in the exhaust gas burner, appropriate monitoring is advantageous.

[0005] The performance of an exhaust gas burner with regard to the homogeneous distribution and introduction of the heating gas into the exhaust stream of an internal combustion engine depends on the positioning of the exhaust gas burner and the design of the connecting section between the exhaust gas burner and the exhaust pipe. This is particularly limited by the available space in the vehicle, so the inlet section may have to be designed or routed differently for each vehicle and engine variant. This requires considerable adaptation effort when integrating a sensor into the exhaust gas burner's outlet section.

[0006] Further exhaust gas burners are known from published patent applications DE 10 2020 125 268 A1, CN 1 10 067 619 A, DE 10 2022 206 800 A1, and DE 42 39 079 A1. A sensor arrangement is known from patent US 9 057 315 ​​B2. Disclosure of the invention

[0007] The exhaust gas burner according to the invention with the features of claim 1 has the advantage that it can be easily and cost-effectively integrated into an exhaust gas aftertreatment system. By designing the sensor arrangement as a sensor module, it can be used in particular as an intermediate piece in a flow guidance system, for example in the outlet section or an outlet duct of the exhaust gas burner. According to the invention, this is achieved in that the sensor is held on a pipe module, wherein the pipe module has a first connection connectable to the exhaust gas burner and a second connection connectable to the outlet pipe or exhaust pipe of the exhaust gas aftertreatment system. The sensor is thus firmly coupled to the pipe module, whereby the orientation and arrangement of the sensor on the pipe module itself can always be optimally designed. The pipe module itself can be adapted to different boundary conditions.The first and second connections allow the pipe module to be easily inserted into the exhaust gas burner's outlet section, particularly in such a way that it can be dismantled without causing any damage.

[0008] Preferably, the tube module has a receiving pocket on a casing wall, in which the sensor is accommodated at least partially. The receiving pocket protects the sensor from external influences, in particular from damage or contamination, to ensure a consistently accurate measurement result. In particular, the receiving pocket protrudes radially outward from the casing wall.

[0009] According to a preferred development of the invention, the receiving pocket forms a volume that is at least 50 times smaller than the volume of the raw module within the casing wall of the sensor arrangement. The heating gas flowing through the tube module enters this volume to be monitored there by the sensor. A small volume ensures that the heating gas flow through the tube module is not noticeably impaired. Furthermore, the sensor itself is protected, for example, from increased flow pressure. The sensor is preferably arranged such that it lies only in the volume of the receiving pocket and thus outside the flow path of the heating gas through the tube module.

[0010] Particularly preferably, the first connection and / or the second connection are each designed as a particularly cylindrical plug connection. This allows the pipe module to be easily inserted into or plugged onto a corresponding mating connection of the combustion chamber or the exhaust pipe, for example. The cylindrical design, in particular, enables a plug-in connection without great additional effort. Preferably, the first connection and / or the second connection has a circular cross-section. Alternatively, the first connection and / or the second connection has a cross-section that deviates from a circular shape, whereby a clear plug-in connection with regard to its orientation is ensured by means of the so-called poka-yoke principle, which prevents incorrect assembly.

[0011] Preferably, the first connection and / or the second connection are each designed as a radially projecting connecting flange. In this case, the first connection and / or the second connection forms an outwardly projecting collar, which can be connected, for example, to a corresponding connecting flange of the exhaust gas burner, in particular the combustion chamber, or the exhaust pipe, in order to be connected thereto, in particular by screwing, clamping, welding, adhesive bonding, or soldering. Welding, adhesive bonding, or soldering of the plug-in connections is also conceivable.

[0012] Preferably, the tube module is designed to be straight, in particular with a cylindrical shell wall. This is particularly suitable for use in connections where the outlet of the exhaust gas burner is aligned with the inlet of the exhaust pipe or an exhaust gas aftertreatment device of the exhaust gas aftertreatment system.

[0013] Alternatively, the tubular module has at least one curvature in its longitudinal extension in order to ensure, for example, optimal use of installation space.

[0014] Furthermore, it is preferably provided that the tube module is designed as an insert module and is arranged at least in sections in the combustion chamber of the exhaust gas burner. According to this embodiment, the tube module or the sensor arrangement, when installed as intended, does not adjoin the exhaust gas burner, in particular the combustion chamber, but rather forms a component of the exhaust gas burner, in particular the combustion chamber. For this purpose, for example, the outer diameter of the tube module is adapted to the inner diameter of the combustion chamber in order to lie flat against it. This results in a particularly space-saving and compact embodiment of the sensor arrangement and of the exhaust gas burner designed in this way.

[0015] Preferably, the first connection of the sensor arrangement is designed to be attached to a flame holder, also called a flame holder, of the combustion chamber, or the first connection forms the flame holder itself. The flame holder is understood to be a baffle in the combustion chamber which has a central baffle opening through which the hot gas flow can leave the combustion chamber. The baffle projects radially outwards to the inside of the casing wall of the combustion chamber, in particular to form a sealing connection therewith. The flame holder ensures that, in particular, no fuel on the casing wall which has not been fully combusted gets into the hot gas in liquid form and can be transported to the exhaust gas aftertreatment system.

[0016] The exhaust gas burner according to the invention with the features of claim 1 is characterized by the inventive design of the sensor arrangement. This results in the advantages already mentioned.

[0017] Particularly preferably, the tube module is connected to the combustion chamber downstream of the combustion chamber. For this purpose, the first connection of the tube module is connected to the combustion chamber outlet.

[0018] According to the invention, the tube module is located at least partially within the combustion chamber and thereby rests against or forms a flame holder of the combustion chamber. This results in the advantages already mentioned above.

[0019] The exhaust gas aftertreatment system according to the invention with the features of claim 11 is characterized by the inventive design of the exhaust gas burner. This results in the advantages already mentioned above.

[0020] Further advantages and preferred features and combinations of features emerge in particular from the above description and from the claims. The invention will be explained in more detail below with reference to the drawings. Fig. 1 an advantageous exhaust gas aftertreatment system with an exhaust gas burner in a schematic representation, Fig. 2 the exhaust gas burner according to a first embodiment with an advantageous sensor arrangement, Fig. 3 the exhaust gas burner according to a second embodiment, Fig. 4 shows another embodiment of the sensor arrangement, Fig. 5 shows a further embodiment of the sensor arrangement, Fig. 6 another embodiment of the exhaust gas burner and Fig. 7 another embodiment of the exhaust gas burner.

[0021] Fig. 1 shows a simplified representation of an advantageous exhaust gas aftertreatment system 1 for an internal combustion engine 2 of a motor vehicle, which in this case is designed as a reciprocating piston engine. A fresh air tract 3 and an exhaust tract 4 are assigned to the internal combustion engine 2. An exhaust pipe 5 of the exhaust tract 4 leads from the exhaust valves of the internal combustion engine 2 to several exhaust gas aftertreatment devices 6, 7, and 8 of the exhaust gas aftertreatment system 1. In this case, viewed in the direction of flow, the first exhaust gas aftertreatment device 6 is a three-way catalyst, the second exhaust gas aftertreatment device 7 is a second three-way catalyst, and the third exhaust gas aftertreatment device 8 is a particulate filter. The exhaust gas from the internal combustion engine flows through the exhaust gas aftertreatment devices 6, 7, and 8 one after the other and serves to reduce pollutant emissions and particles in the exhaust gas.To ensure that the exhaust gas 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 gas 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 through an injection valve 12 and oxygen-containing gas, in this case air, through a guide device 13, in order to be ignited and combusted in the combustion chamber with the aid of an ignition device 14. The combusted fuel / air mixture is supplied through an outlet opening 15 of the exhaust gas burner 10 to the exhaust tract 4 upstream of the first catalytic converter 6, so that the heated gas mixture increases the operating temperature of the exhaust gas aftertreatment devices 6, 7, 8 even before the internal combustion engine 2 itself has reached its necessary operating temperature.

[0022] A controllable valve device 16 is connected upstream of the exhaust gas burner 10, by means of which the supplied air flow can be adjusted. An air pump or air conveying device 17 is advantageously arranged upstream of the valve device 16, by means of which fresh air can be drawn in and conveyed toward the valve device 16. An air mass meter 18 and an air filter 19 are also connected upstream of the air conveying device 17.

[0023] A control unit 20 of the heating system controls or operates the air mass meter 18, the air pump 17, the valve device 16, and the exhaust gas burner 10 to generate a heated air-fuel mixture to the desired degree, which is fed to the exhaust tract 4 to heat the exhaust gas aftertreatment devices 6, 7, 8. The control unit 20 is in particular in communication with a control unit 21 of the internal combustion engine.

[0024] Fig. 2 shows the exhaust gas aftertreatment system 1 in the region of the exhaust gas burner 10 according to a first advantageous embodiment. As already mentioned, the exhaust gas burner 10 has a combustion chamber 11, to which the ignition device 14, for example in the form of a spark plug or glow plug, is assigned, as well as the injection valve 12 and the guide device 13. The guide device 13 and the injection valve 12 are designed such that the fuel and the oxygen-containing gas are introduced into the combustion chamber 11 at a first end face 22 thereof. The guide device 13 opens into the combustion chamber through a gas inlet 40, in particular through an annular gas inlet 40 formed coaxially with the outlet opening of the injection valve 12. On the end face 23 facing away from the end face 22, the combustion chamber 11 has a flame holder 24, which forms an orifice with an orifice opening 25.The aperture 25 is arranged centrally, and the aperture is thus annular, in particular circular, with its outer edge sealingly abutting against the casing wall 26 of the combustion chamber 11. Viewed in longitudinal section, the aperture is V-shaped and widens in the direction of flow. The flame holder 24 ensures that the combusted fuel gas leaves the combustion chamber 11 through the outlet 15, while any unburned fuel that may have precipitated on the casing wall 26 of the combustion chamber 11 is prevented by the flame holder 24 from escaping the exhaust gas burner 10 and entering the downstream exhaust tract 4 of the exhaust gas aftertreatment system 1 unburned.

[0025] The combustion chamber 11 is connected to the exhaust pipe 5 upstream of the exhaust aftertreatment device 6 by an outlet duct 27. The outlet duct 27 is expediently assigned to the outlet 15.

[0026] In the present case, a sensor arrangement 28 is arranged between the outlet 15 and the outlet channel 27. The sensor arrangement 28 comprises a sensor 29, which is designed in particular as a lambda probe, and a pipe module 30. The pipe module 30 has a cylindrical pipe section 31, each of which has a connecting flange 32 or 33 on its end faces. The connecting flange 32 is connected to a connecting flange of the combustion chamber 11, and the connecting flange 33 is connected to a connecting flange of the outlet channel 27. By designing the axial end faces or ends of the pipe module 30 as connecting flanges, it can be easily connected to the other components of the exhaust gas burner 10 by screwing and can thus be integrated into the latter. In particular, the pipe module 30 can be removed without causing damage, thus enabling simple maintenance and replacement.

[0027] While according to the embodiment of Fig. 2 the tube module 30 extends straight, shows Fig. 3 shows a further embodiment in which the pipe module 30 has a curved profile and is therefore integrated into the exhaust gas burner 10 or into the outlet channel 27 at a greater distance from the combustion chamber 11. The outlet channel 27 is curved in such a way that, when installed as intended, it forms a siphon 34 in which condensate can collect and subsequently be evaporated. Depending on the design of the pipe module 30, it can be used at different locations along the length of the outlet channel. The position of the sensor 29 can be optimally positioned depending on the available installation space, the performance of the exhaust gas burner 10, and the flow path of the heating gas.

[0028] Fig. 4 shows a further embodiment of the sensor arrangement 28, which differs from the previous embodiments in that the pipe module 30 has only one connecting flange 32, which is assigned to the combustion chamber 11 or a section of the exhaust duct 27. At its other end, the pipe module 30 has a cylindrical plug connection 35, which can be inserted or plugged into or onto a connecting element of the exhaust pipe. In the embodiment of Fig. 4, the outer diameter of the plug-in connector 35 is smaller than the inner diameter of the connecting element 36, so that the pipe module 30 with the plug-in connector 35 is inserted into the connecting element 36. Both in the variant as a connecting flange 32, 33 and in the variant as a plug-in connector 35, an alternative or additional connection of the elements to one another can be realized by welding, soldering, and / or gluing.

[0029] Fig. 5 shows a further embodiment of the tube module 30, which differs from the previous embodiment in that the tube module 30 or the tube section 31 has a plug connection 35 and 37 on each of its two end faces. Thus, in this case, a plug connection 37 is also formed on the inlet side of the tube module 30. In this case, the plug connection 37 is designed to be pushed onto the outlet of the combustion chamber 11 or a section of the outlet channel 27.

[0030] In any case, the pipe module 30 can be easily connected to the exhaust burner 10, the outlet duct 27, and / or the exhaust pipe 5 during assembly. By designing the sensor arrangement 28 in this modular form, the sensor module can be used variably and optimally adapted to the boundary conditions mentioned above.

[0031] Fig. 6 shows a further embodiment that differs from the previous embodiments in that the sensor assembly 28 or the sensor module is integrated into the combustion chamber 11 of the exhaust gas burner 10. For this purpose, the tube module 30 is designed such that it can be integrated or inserted into the combustion chamber 11.

[0032] For this purpose, the outer diameter of the tube module 30 is ensured such that it corresponds to or almost corresponds to the inner diameter of the casing wall 26, wherein the inlet-side end face of the tube module 30 is designed to lie flat against the flame wall 24 and is configured to correspond thereto. Optionally, the inlet-side end face of the tube module 30 forms the flame wall 24 in the combustion chamber 11. The sensor arrangement 28 is thus a particularly integral component of the exhaust gas burner 10.

[0033] Optionally, to integrate the sensor arrangement 28, the combustion chamber 11 is shortened in its axial extent in order to keep or maintain the overall length of the combustion chamber 11 constant. The space following the flame holder 24 in the direction of flow is enlarged to such an extent that the lambda probe or sensor 29 can be accommodated in the intermediate space. To achieve good mixing of gas and fuel in the shortened combustion chamber section, the swirl number of the supplied gas is preferably increased. For this purpose, for example, a swirl grid 38 of the guide device 13 is adapted.

[0034] As shown in the previous embodiments, the pipe module 30 has a radially outwardly projecting receiving pocket 39, in which the sensor 29 is at least partially accommodated. The receiving pocket 39 has a volume that is approximately 50 times smaller than the volume of the pipe section 31. The heating gas advantageously collects in this volume for monitoring by the sensor 29.

[0035] Fig. 7 shows an advantageous development of the embodiment of Fig. 6, according to which the tube module 30 is not arranged within the combustion chamber 11, but directly adjoins the combustion chamber 11 in its extension or to its extension. In this case, the tube module 31 advantageously forms the flame holder 24. Due to the fact that the tube module 30 extends the combustion chamber 11, a simplified integration, in particular of the sensor, into the exhaust gas burner 10 is ensured, since for the radial passage of the sensor 29 no additional recess has to be created in the casing wall 26 of the combustion chamber 11, as in the embodiment of Fig. 6 is the case. This simplifies the structural design and assembly of the exhaust gas burner 10.

[0036] Optionally, the sensor 29 is assigned a cooling device, which can be integrated in particular in a cooling circuit of the exhaust gas aftertreatment system 1 or the internal combustion engine 2, so that the sensor 29 can be cooled by the cooling device during operation in order to maximize the service life of the sensor 29.

Claims

[1] Exhaust gas burner (10) for an exhaust gas aftertreatment system (1), comprising a combustion chamber (11) 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 combustion chamber (11), and wherein the combustion chamber (11) has a guide device (13) with a gas inlet (22) for the gas and a heating gas outlet (15) for the heating gas, wherein a sensor arrangement (28) with at least one sensor (29), in particular a lambda probe, which can be arranged or is arranged downstream of a combustion chamber (11) of the exhaust gas burner (10) is assigned to the heating gas outlet, wherein the sensor (29) is held on a pipe module (30),wherein the pipe module (30) has a first connection connectable to the exhaust gas burner (10) and a second connection connectable to an outlet duct (27) or exhaust pipe (5) of an exhaust gas aftertreatment system (1), , characterized by that the tube module (30) is located at least in sections in the combustion chamber (11) and rests against or forms a flame holder (24) of the combustion chamber (11). [2] Exhaust gas burner according to claim 1, characterized by that the pipe module (30) has a receiving pocket (39) on a casing wall, in which the sensor (29) is received at least in part. [3] Exhaust gas burner according to claim 2, characterized by that the receiving pocket (39) forms a volume which is at least 50 times smaller than a volume of the tube module (30) within the jacket wall. [4] Exhaust gas burner according to one of the preceding claims, characterized bythat the first connection and / or the second connection is each designed as a particularly cylindrical plug connection (35). [5] Exhaust gas burner according to one of the preceding claims, characterized by that the first connection and / or the second connection is each designed as a radially projecting connecting flange (32,33). [6] Exhaust gas burner according to one of the preceding claims, characterized by that the pipe module (30) is designed to be straight, in particular with a cylindrical jacket wall. [7] Exhaust gas burner according to one of the preceding claims, characterized by that the tube module (30) has at least one curvature in its longitudinal extent. [8] Exhaust gas burner according to one of the preceding claims, characterized by that the pipe module (30) is designed as an insert module for at least partial insertion into the combustion chamber (11) of the exhaust gas burner (10). [9] Exhaust gas burner according to one of the preceding claims, characterized by that the first connection is designed to be attached to a flame holder (24) of the combustion chamber (11) or the flame holder (24). [10] Exhaust gas burner according to one of the preceding claims, characterized by that the tube module (30) is connected to the combustion chamber (11) downstream of the combustion chamber (11). [11] Exhaust gas aftertreatment system (1) for an internal combustion engine (2) of a motor vehicle, with at least one exhaust gas aftertreatment device (6, 7, 8), in particular a catalytic converter, three-way catalytic converter or particulate filter, and with at least one exhaust gas burner (10) which is fluidically connected upstream of the at least one exhaust gas aftertreatment device (7, 8, 9), characterized by the design of the exhaust gas burner (10) according to one of claims 1 to 10.

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