Burner for a motor vehicle as well as motor vehicle

Abstract

The invention relates to a burner (10) for an exhaust tract through which exhaust gas from an internal combustion engine flows, comprising a combustion chamber (12) in which a mixture comprising air and fuel is to be ignited and thereby combusted, comprising an inner swirl chamber (18) through which a first part of the air flows, which has a first swirl-generating device (38) by means of which a swirl-shaped flow of the first part of the air can be effected, and a first outlet opening (20) through which the first part of the air flows, and comprising an outer swirl chamber (28) surrounding at least a longitudinal region of the inner swirl chamber (18) in the circumferential direction of the inner swirl chamber (18), through which a second part of the air flows, which has a second swirl-generating device (40) by means of which a swirl-shaped flow of the second part of the air can be effected,and has a second outlet opening (32) through which the second part of the air flows and the first part of the air flows through the inner swirl chamber (18) and the first outlet opening (20).

Description

The invention relates to a burner for an exhaust tract through which exhaust gas from an internal combustion engine of a motor vehicle can flow, according to the preamble of patent claim 1.DE 10 2021 001 580 A1 discloses a burner for an exhaust tract through which exhaust gas from an internal combustion engine of a motor vehicle can flow, having a combustion chamber in which a mixture comprising air and a liquid fuel is to be ignited and thereby burned.It is the object of the present invention to provide a burner for a motor vehicle and a motor vehicle having at least one such burner, so that particularly advantageous operation of the burner can be ensured.This object is achieved by a burner having the features of patent claim 1 and by a motor vehicle having the features of patent claim 10. Advantageous embodiments with expedient developments of the invention are specified in the other claims.A first aspect of the invention relates to a burner for an exhaust tract through which exhaust gas from an exhaust tract, which is also referred to as an internal combustion engine or internal combustion engine or engine and is preferably designed as a reciprocating piston engine, that is to say as a reciprocating piston engine of a motor vehicle which is also referred to simply as a vehicle, can flow. This means that the motor vehicle, which can preferably be designed as a motor vehicle and very particularly as a passenger vehicle, has the internal combustion engine and the exhaust tract in its completely produced state and can be driven by means of the internal combustion engine. During a fired operation of the internal combustion engine, combustion processes take place in the internal combustion engine, in particular in at least one or more combustion chambers of the internal combustion engine, resulting in the exhaust gas of the internal combustion engine, which is also referred to as engine exhaust gas. The engine exhaust gas can flow out of the respective combustion chamber and into the exhaust tract and subsequently flow through the exhaust tract, also referred to as exhaust system. At least one component, such as an exhaust gas aftertreatment element for aftertreating the exhaust gas, may be arranged in the exhaust tract. The exhaust gas aftertreatment element is or comprises, for example, a catalyst, in particular an SCR catalyst, wherein, for example, a selective catalytic reduction (SCR) can be catalytically supported and / or effected by means of the SCR catalyst, such that, for example, the SCR catalyst is catalytically active for the SCR. In the selective catalytic reduction, any nitrogen oxides present in the engine exhaust gas are at least partially removed from the exhaust gas, in that, in the selective catalytic reduction, the nitrogen oxides react with ammonia to form nitrogen and water. The ammonia is provided, for example, by an in particular liquid reducing agent, which can be an aqueous urea solution. It is furthermore conceivable for the exhaust gas aftertreatment element to be a particle filter or to comprise a particle filter. More specifically, the particulate filter is a diesel particulate filter (DPF). By means of the particle filter, any particles contained in the exhaust gas, in particular soot particles, can be filtered out of the exhaust gas.The burner has a combustion chamber, also referred to as a main combustion chamber, in which a mixture comprising air and a preferably liquid fuel can be ignited and thereby burnt. In particular, the combustion chamber is delimited, in particular directly, by a chamber element, which is in particular embodied as a solid body, in particular by an inner-circumferential lateral surface of the chamber element. As a result of the combustion of the mixture taking place in particular in the combustion chamber, an exhaust gas of the burner, also referred to as burner exhaust gas, is generated, in particular in the combustion chamber. The burner exhaust gas can flow out of the combustion chamber, for example, and into the exhaust tract, that is to say, for example, into an exhaust gas duct of the exhaust tract through which the engine exhaust gas can flow, in particular at an introduction point which is arranged upstream of the aforementioned component, for example, in the flow direction of the engine exhaust gas (exhaust gas of the internal combustion engine) flowing through the exhaust tract or the exhaust gas duct. For example, the burner exhaust gas mixes with the engine exhaust gas. As a result, the burner exhaust gas, in particular the burner exhaust gas mixed with the engine exhaust gas, can flow through the component, for example, as a result of which the component can be heated, that is to say heated. In particular, it is conceivable that the burner exhaust gas can flow out of the combustion chamber and into the exhaust tract or into the aforementioned exhaust tract and is thereby mixed with the engine exhaust gas flowing through the exhaust tract and / or with a gas flowing through the exhaust tract, whereby the engine exhaust gas or the gas is heated. In other words, this makes it possible to realize a particularly high temperature, also referred to as the exhaust gas temperature, of the engine exhaust gas or of the gas. In particular, the gas can be, for example, air which flows, for example, through the exhaust tract or the exhaust gas channel, in particular while the internal combustion engine is being dragged, that is to say while a fired operation of the internal combustion engine is not being carried out, with the internal combustion engine not providing any engine exhaust gas, with the gas, in particular the air, then being conveyed through the exhaust tract by the internal combustion engine, for example. The component can be heated by the high exhaust gas temperature, since the burner exhaust gas and, for example, the engine exhaust gas or the gas flows through the component. Thus, for example, the burner exhaust gas is introduced from the combustion chamber at the aforementioned introduction point into the exhaust tract, in particular into the exhaust tract, and thus into the engine exhaust gas or gas flowing through the exhaust tract or the exhaust tract.For example, an ignition device, in particular an electrically operable ignition device, is provided, wherein the burner can comprise the ignition device. In particular, it is conceivable for the ignition device to be arranged at least partially in the combustion chamber. By means of the ignition device, in particular in the combustion chamber and / or using electrical energy, at least one ignition spark can be provided, i.e. generated, for igniting the mixture, so that in particular by means of the ignition spark the mixture can be ignited, in particular in the combustion chamber. The ignition device can be designed, for example, as a spark plug or as a glow plug.The burner has an inner swirl chamber through which a first part of the air forming the mixture, in particular in the combustion chamber, can flow and which brings about a swirling flow of the first part of the air, which swirl chamber is thus preferably arranged upstream of the combustion chamber in the flow direction of the first part of the air flowing through the inner swirl chamber. In the following, when the term air is used, unless otherwise stated, this is to be understood as meaning the air forming the mixture, in particular in the combustion chamber, that is to say the air from which the mixture is formed in particular together with the fuel. The inner swirl chamber has, in particular precisely, a first outflow opening through which the first part of the air flowing through the inner swirl chamber can flow, via which the first part of the air flowing through the first outflow opening can be discharged from the inner swirl chamber and introduced, for example, into the combustion chamber. Thus, in particular, the combustion chamber is arranged downstream of the inner swirl chamber in the flow direction of the first part of the air flowing through the inner swirl chamber. The feature that the inner swirl chamber brings about or can bring about a swirling flow of the first part of the air flowing through the inner swirl chamber is to be understood in particular as meaning that the first part of the air flows through the inner swirl chamber in a swirling manner, and therefore flows through at least a first partial region of the inner swirl chamber in a swirling manner, and / or the first part of the air only has its swirling flow at least in a first flow region which is arranged downstream of the inner swirl chamber and outside the inner swirl chamber and is arranged, for example, in the combustion chamber. In particular, it is conceivable for the first part of the air to flow out of the inner swirl chamber in a swirling manner via the first outflow opening and / or to flow into the combustion chamber in a swirling manner, so that it is very preferably provided that the first part of the air has its swirling flow at least in the combustion chamber. In particular, it is conceivable that the first part of the air already has its swirling flow in the inner swirl chamber, namely at least in the aforementioned, a first subregion of the inner swirl chamber.For example, the burner can have an introduction element, in particular an injection element, which has at least or exactly one outlet opening through which the preferably liquid fuel can flow. In particular, it is conceivable for the introduction element to have a plurality of, in particular more than two, outlet openings through which the preferably liquid fuel can flow. By means of the introduction element, the fuel can be introduced, in particular injected, for example into the inner swirl chamber, in particular directly, such that the fuel, which is preferably liquid, can also be flown through by, in particular injected, the first outflow opening, for example, by the preferably liquid fuel which has emerged, in particular injected, from the introduction element via the outlet opening and is thereby introduced, in particular injected, directly into the inner swirl chamber. This means in particular that the first part of the air and, for example, also the fuel can flow through the first outflow opening along a first flow direction, in particular in the first flow direction, which is common in particular in the first part of the air and the fuel, and can thereby flow out of the inner swirl chamber.Furthermore, the burner comprises an outer swirl chamber which surrounds at least one length region of the inner swirl chamber and in this case preferably also the first outflow opening in the circumferential direction of the inner swirl chamber, in particular in a completely circumferential manner. The circumferential direction of the inner swirl chamber extends, for example, around the aforementioned first flow direction, which extends, for example, in the axial direction of the inner swirl chamber and thus of the first outflow opening, and therefore with the axial direction of the inner swirl chamber, the radial direction of which extends perpendicular to the axial direction of the inner swirl chamber, and thus coincides with the outflow opening. It is preferably provided that the inner swirl chamber ends at the first outflow opening or at its end in the flow direction of the first part flowing through the first outflow opening and thus for example in the flow direction of the fuel flowing through the first outflow opening, thus in the axial direction of the inner swirl chamber and thus of the first outflow opening. A second part of the air can flow through the outer swirl chamber, the axial direction of which coincides with the axial direction of the inner swirl chamber, and is designed to bring about a swirling flow of the second part of the air. This is to be understood in particular as meaning that the second part of the air flows in the outer swirl chamber in a swirling manner, and therefore flows through at least a second partial region of the outer swirl chamber in a swirling manner, and / or the second part of the air has its swirling flow in a second flow region arranged downstream of the outer swirl chamber in the flow direction of the second part of the air flowing through the outer swirl chamber, which second flow region can coincide with the aforementioned first flow region, wherein the second flow region can be arranged, for example, outside the outer swirl chamber and, for example, inside the combustion chamber. It is furthermore conceivable for the aforementioned first flow region to be arranged outside the outer swirl chamber. In other words, it is conceivable that the second part of the air flows out of the outer swirl chamber in a swirling manner and / or flows into the combustion chamber in a swirling manner, so that it is preferably provided that the second part of the air has its swirling flow at least in the combustion chamber.The outer swirl chamber has, in particular precisely, a second outflow opening through which the second part of the air flowing through the outer swirl chamber and the first part of the air flowing through the inner swirl chamber and the first outflow opening, and preferably also a second outflow opening through which the fuel flowing through the first outflow opening can flow and which is arranged, for example, downstream of the first outflow opening in the direction of flow of the parts of the air and in particular of the fuel, via which second part of the air can be discharged from the outer swirl chamber and the parts of the air and in particular of the fuel can be introduced into the combustion chamber.In particular, the feature that the outer swirl chamber brings about or can bring about a swirling flow of the second part of the air flowing through the outer swirl chamber is to be understood to mean that the second part of the air flows through the outer swirl chamber in a swirling manner, and therefore flows through at least a second partial region of the outer swirl chamber in a swirling manner, and / or the second part of the air only has its swirling flow at least in a second flow region arranged downstream of the outer swirl chamber and outside of the outer swirl chamber, which second flow region is arranged, for example, in the combustion chamber. In particular, it is conceivable for the second part of the air to flow out of the outer swirl chamber in a swirl-like manner via the second outflow opening and / or to flow into the combustion chamber in a swirl-like manner, so that it is very preferably provided that the second part of the air has its swirl-like flow at least in the combustion chamber. In particular, it is conceivable that the second part of the air already has its swirling flow in the outer swirl chamber, namely at least in the aforementioned at least one second subregion of the outer swirl chamber.In particular, it can thus be provided that the combustion chamber is arranged downstream of the inner swirl chamber and / or downstream of the outer swirl chamber in the flow direction of the respective part of the air flowing through the respective swirl chamber. In particular, the parts of the air and in particular also of the fuel can flow along a second flow direction, in particular in the second flow direction, through the second outflow opening and thus flow into the combustion chamber via the second outflow, wherein for example the second flow direction runs parallel to the first flow direction or coincides with the first flow direction. Furthermore, it is preferably provided that the second flow direction runs in the axial direction of the outer swirl chamber, thus coincides with the axial direction of the outer swirl chamber, the radial direction of which runs perpendicular to the axial direction of the outer swirl chamber, so that, for example, the radial direction of the outer swirl chamber coincides with the radial direction of the inner swirl chamber. Thus, it is quite preferably provided that the axial direction of the inner swirl chamber corresponds to the axial direction of the outer swirl chamber or vice versa. Furthermore, it is preferably provided that the radial direction of the outer swirl chamber coincides with the radial direction of the inner swirl chamber and vice versa. The respective axial direction of the respective swirl chamber runs perpendicular to the respective radial direction of the respective swirl chamber, wherein the radial direction of the inner swirl chamber preferably coincides with the radial direction of the outer swirl chamber and vice versa. Since, for example, the second outflow opening is arranged along the respective flow direction, that is to say in the flow direction of the respective part of the air and, for example, downstream of the first outflow opening in the flow direction of the fuel, and since the outer swirl chamber preferably surrounds the first outflow opening, the first outflow opening is arranged, for example, in the outer swirl chamber. In particular, it is conceivable for the outer swirl chamber to end at the second outflow opening, in particular at the end thereof, in particular in the flow direction of the second part of the air flowing through the second outflow opening.In order to generate the swirling flow of the first part of the air, the inner swirl chamber has a first swirl generation device, by means of which the swirling flow of the first part of the air can be effected. For example, the first swirl-generating device has first swirl-generating elements, by means of which the first swirling flow of the first part of the air can be effected. The first swirl-generating elements are also referred to as first swirl generators, which can be arranged in particular in the inner swirl chamber. Furthermore, the outer swirl chamber has a second swirl-generating device, by means of which the swirling flow of the second part of the air can be effected. For example, the second swirl-generating device has second swirl-generating elements, by means of which the swirling flow of the second part of the air can be effected. The first swirl generating device is also referred to as an inner swirl generating device, and the second swirl generating device is also referred to as an outer swirl generating device. By means of the second swirl-generating device, in particular by means of the second swirl-generating elements, the second swirling flow of the second part of the air can be effected. The second swirl-generating elements are also referred to as second swirl generators, which can be arranged, for example, in the outer swirl chamber. In particular, the respective swirl generating element, and therefore the respective swirl generator, can be, for example, a respective guide blade, by means of which, for example, the respective part, that is to say the respective air forming the respective part, can be deflected or is deflected at least or exactly once, in particular by at least or exactly 70 degrees, in particular by at least substantially 90 degrees, and very particularly, for example, by 70 degrees to 90 degrees. In particular, the respective swirling flow is understood to mean a flow which extends in a swirling manner, that is to say at least substantially helically or helically, about the respective axial direction of the respective swirl chamber or of the respective outflow opening. In particular, the respective axial direction of the respective outflow opening runs perpendicular to a plane in which the respective outflow opening runs. In this case, for example, the respective axial direction of the respective outflow opening coincides with the respective axial direction of the respective swirl chamber. The respective outflow opening is also referred to as a respective nozzle, for example, whose cross section through which the respective part of the air can flow narrows along the respective flow direction. Thus, for example, the second outflow opening is also referred to as an outer nozzle or second nozzle, wherein, for example, the first outflow opening is also referred to as an inner nozzle or first nozzle.By causing the respective swirling flow, the air can be mixed with the preferably liquid fuel particularly advantageously, in particular via an even only small mixing path, in particular in the combustion chamber, such that a particularly advantageous mixture treatment can be realized, that is to say the mixture can be formed particularly advantageously. In particular, the fuel, in particular in the inner swirl chamber, can first be mixed particularly well with the first part of the air, in particular on account of the swirling flow of the first part of the air, in particular in the inner swirl chamber. In addition, the fuel and, for example, also the first part of the air already mixed with the fuel can be mixed particularly advantageously with the second part of the air, in particular in the outer swirl chamber and / or in the combustion chamber, since the second part of the air also has an advantageous swirling flow. Overall, due to the swirling flows, the parts of the air and the fuel can be mixed with one another in a particularly advantageous manner, so that a particularly advantageous mixture preparation can be produced in the combustion chamber.Since, for example, the burner exhaust gas can flow out of the combustion chamber and into the exhaust tract or into the exhaust tract, respectively, via at least or exactly one or via a plurality of outlet openings of the combustion chamber or of the chamber element, at least a part of the engine exhaust gas flowing through the exhaust tract can flow into the combustion chamber, for example vice versa and in particular when operation of the burner fails, in particular via the at least one outlet opening. The engine exhaust gas may contain constituents such as, for example, the aforementioned soot particles and / or other, further constituents. In order to now prevent the engine exhaust gas or the components contained in the engine exhaust gas from leading to an excessive, undesirable impairment of the burner, such as, for example, to a contamination of the respective outflow opening, the burner additionally has at least or exactly one closure element, which is movable relative to the outflow openings and in this case, in particular relative to the chamber element, between at least one closed position, which closes at least one of the outflow openings and thereby fluidically blocks it, and at least one open position, which opens the at least one outflow opening. The closed position is also referred to as a first position or is a first position of the closure element, and the open position is also referred to as a second position or is a second position of the closure element. In the closed position, no gases and no particles, in particular from the combustion chamber, can enter the at least one outflow opening or penetrate the at least one outflow opening, so that no gases, such as the engine exhaust gas and also no particles, can penetrate or penetrate into the swirl chamber having the at least one outflow opening. As a result, a particularly advantageous mixture treatment can be achieved even over a particularly long service life of the burner, since the mixture treatment is not impaired by particles or gases which have penetrated into undesired regions of the burner and which can lead to formation of deposits in the region of the outflow openings.In order to be able to ensure particularly advantageous operation of the burner in particular also over a long service life of the burner, it is provided according to the invention that the closure element slides, in particular directly, along the surfaces of the burner directly and at least partially delimiting the first outflow openings at least during its movement from one of the positions into the other position. For example, the first outflow opening is at least partially, in particular at least predominantly and thus to more than half or even completely, circumferentially and directly delimited by the mentioned surfaces in the circumferential direction of the first outflow opening, which circumferential direction runs around the axial direction of the first outflow opening, which circumferential direction is formed, for example, as an inner-circumferential-side and thus in particular concave lateral surface of the burner and an outer-circumferential-side and thus in particular convex lateral surface of the burner.The feature that the closure element slides along the surfaces of the burner at least partially and directly delimiting the first outflow opening at least during the movement of the closure element from the one position into the other position is to be understood to mean that at least when the closure element is moved from the one position into the other position, the closure element directly touches the surfaces and slides directly along the surfaces, such that the closure element scrapes directly along the surfaces. In this case, the closure element scrapings off any contamination, such as particles, adhering to the surface, so that an undesired, excessive clogging of the first outflow opening, and therefore an excessive, undesired reduction in the cross-section of the at least one outflow opening, can be counteracted. In this way, an advantageous mixture preparation can be ensured even over a long service life of the burner, so that an advantageous operation of the burner can be ensured even over a long service life of the burner. It is preferably provided that the closure element slides directly along the surfaces even when the closure element moves from the other position into the one position and thus slides directly along the surfaces. As a result, any contamination adhering to the surface, such as particles, can be scraped off the surface and thus removed, so that advantageous mixture preparation can be ensured even over a long service life.For example, the fact that the burner is not in operation is to be understood as meaning that no fuel is introduced into the respective swirl chamber by means of the introduction element and that the respective swirl chamber is also not supplied with air. The invention can now also remove such contaminants from the surface that settle on the surface, for example, in the open position of the closure element and / or in the closed position of the closure element despite the closed position of the closure element. The closure element is thus used as a cleaning element, by means of which contaminants which have deposited on the surfaces can be removed, in that, when the closure element is moved from the one position into the other position and preferably also from the other position into the one position, it slides directly on the surfaces and thus scrapes off the contaminants from the surfaces.In order to be able to clean a second surface particularly advantageously and thus also ensure advantageous mixture preparation over a long service life of the burner, it is provided in an embodiment of the invention that the closure element has a first part with a conical partial region which slides along the second surface of the burner, in particular directly, at least during the movement of the closure element from the one position into the other position and preferably also from the other position into the one position, and thus scraping off any soiling from the second surface.It has been shown to be particularly advantageous if the conical sub-region in the closed position encompasses the first outflow opening, which is directly and at least partially delimited by the second surface, along which the closure element slides at least during the movement of the closure element from the one position into the other position. As a result, contaminants which are also securely seated on the second surface can advantageously be scraped off from the second surface and thus removed.Furthermore, it has been shown to be particularly advantageous if the first part of the closure element has a plug which penetrates into the first outflow opening at least during the movement of the closure element from the one position into the other position and slides along the first surface of the burner. As a result, contaminants which are also firmly seated on the first surface can advantageously be scraped off from the first surface and thus removed.A further embodiment is distinguished in that the conical subregion, in the closed position of the closure element, widens in the direction of the swirl chambers. This makes it possible to ensure that, when the closure element is moved at least from the one position into the other position, the closure element slides along the second surface over a long path, so that the second surface can be cleaned in a particularly advantageous manner.In a further, particularly advantageous embodiment of the invention, it is provided that the conical subregion protrudes from a wall region of the closure element adjoining the subregion. This allows the surface to be cleaned in a targeted manner, so that advantageous mixture preparation can be ensured even over a long service life of the burner.A further embodiment is distinguished in that the conical subregion has at least one slot, which is in particular designed as a through-opening and which is preferably bounded, in particular directly, in a completely encircling manner along its circumferential direction by the conical subregion. Furthermore, it is conceivable that the slot is bounded at one end, in particular directly, by the conical sub-region, in particular along its longitudinal extension direction, and at the other end, when the conical sub-region is viewed alone, is unlimited and thus opens into or onto an environment of the conical sub-region. By means of the slot, for example, a certain, in particular non-destructive and / or elastic compressibility of the conical sub-region can be ensured, in particular in relation to the closed position of the closure element in the radial direction of the outer swirl chamber. As a result, for example, the conical partial region can particularly advantageously conform or bear against the second surface and thus slide particularly well along the second surface and as a result advantageously scrape off any soiling from the second surface.It has proven particularly advantageous if the conical sub-region has a plurality of slots, namely the aforementioned at least one slot and at least one further slot or a plurality of further slots. This can ensure a particularly advantageous compressibility of the conical sub-region, so that the latter can adapt to the second surface in a particularly advantageous manner. Thus, when the closure element is moved from the one position into the other position, the second surface can be advantageously cleaned, since contaminants can be scraped off the second surface particularly advantageously by means of the closure element.A further embodiment is characterized in that the slots are arranged uniformly distributed in the circumferential direction of the conical sub-region. As a result, the conical partial region can be compressed particularly advantageously and in particular elastically and / or non-destructively, in particular in relation to the closed position of the closure element in the radial direction of the outer swirl chamber, so that the closure element can particularly advantageously scrape contaminants from the second surface. At least in the closed position of the closure element, the circumferential direction of the conical subregion runs around the respective axial direction of the outer swirl chamber. Thus, the circumferential direction of the conical sub-region, the cone axis of which, simply also referred to as axis, is also referred to as cone axis, extends around the axis of the conical sub-region, which is formed rotationally symmetrically with respect to the axis. In the closed position, the axis of the conical subregion thus coincides with the axial direction of the outer swirl chamber.Finally, it has been shown to be particularly advantageous if the closure element is pivotable between the positions about a pivot axis relative to the outflow openings. As a result, the closure element can slide along the surfaces in a particularly advantageous manner and thus clean the surfaces in a particularly advantageous manner. Preferably, it is provided that the pivot axis extends perpendicular to the axial direction of the respective swirl chamber. This means that the pivot axis runs perpendicular to a first plane, wherein the respective axial direction of the respective swirl chamber runs perpendicular to a second plane, and wherein the planes run perpendicular to one another.A second aspect of the invention relates to a motor vehicle, which is also referred to simply as a vehicle and is preferably designed as a motor vehicle, in particular as a passenger car, and which has an internal combustion engine and can be driven by means of the internal combustion engine. The motor vehicle also has an exhaust tract through which exhaust gas from the internal combustion engine can flow, which exhaust tract has at least one burner according to the first aspect of the invention. Advantages and advantageous configurations of the first aspect of the invention are to be regarded as advantages and advantageous configurations of the second aspect of the invention and vice versa.Further advantages, features and details of the invention are evident from the following description of preferred exemplary embodiments and with reference to the drawing. The features and combinations of features mentioned above in the description and the features and combinations of features mentioned below in the description of the figures and / or shown alone in the figures can be used not only in the respectively specified combination but also in other combinations or alone without departing from the scope of the invention.The drawing shows in: FIG. 1 shows a schematic longitudinal sectional view of a burner for an exhaust tract through which exhaust gas of an internal combustion engine of a motor vehicle can flow; FIG. 2 shows a detail of a further schematic longitudinal sectional view of the burner with a first embodiment of a closure element; and FIG. 3 shows a schematic side view of a second embodiment of the closure element in a detail.In the figures, identical or functionally identical elements are provided with identical reference symbols.FIG. 1 shows a schematic sectional view of a portion of a burner 10 for an exhaust tract through which exhaust gas from an internal combustion engine of a motor vehicle can flow. The exhaust gas of the internal combustion engine is also referred to as engine exhaust gas. The motor vehicle, which is also referred to simply as a vehicle and is preferably designed as a motor vehicle, in particular as a passenger vehicle, has a drive device, not shown in the figures, by means of which the motor vehicle can be driven. The drive device has the internal combustion engine. The motor vehicle, in particular the drive device, has the exhaust tract. The motor vehicle is a land vehicle. The internal combustion engine is also referred to as an internal combustion engine, an internal combustion engine or a motor. The internal combustion engine has an engine block, also referred to as an engine housing. Furthermore, the internal combustion engine has at least one or more cylinders which are formed or bounded by the engine block, in particular directly. During a fired operation of the internal combustion engine, respective combustion processes take place in combustion chambers of the cylinders, resulting in the engine exhaust gas. For this purpose, within a respective working cycle of the internal combustion engine, an in particular liquid fuel is introduced into the respective combustion chamber, in particular directly injected. The internal combustion engine can be designed as a diesel engine, so that the fuel is preferably a diesel fuel. A fuel tank is provided in this case, also referred to as a tank, in which the fuel can be received or is accommodated. A respective injector is assigned to the respective cylinder, for example, by means of which the fuel can be introduced, in particular directly injected, into the respective combustion chamber. For example, the fuel is conveyed from the tank by means of a low-pressure pump to a high-pressure pump, by means of which the fuel is conveyed to the injectors or to a fuel distribution element common to the injectors and also referred to as a rail or common rail. The injectors can be supplied with the fuel from the fuel distribution element common to the injectors by means of the fuel distribution element and can introduce, in particular directly inject, the fuel from the fuel distribution element into the respective combustion chamber.The drive device comprises, for example, an intake tract through which fresh air can flow, by means of which the fresh air flowing through the intake tract is guided to the cylinders and into the respective combustion chambers. The fresh air forms with the fuel a fuel-air mixture, which comprises the fresh air and the fuel and is ignited within the respective working cycle in the respective combustion chambers of the cylinders and is thereby burned. In particular, the fuel-air mixture is ignited by self-ignition and thereby burned. The ignition and combustion of the fuel-air mixture results in the engine exhaust gas of the internal combustion engine. The drive device has the exhaust tract through which the exhaust gas can flow from the cylinders. The internal combustion engine or the drive device also comprises, for example, an exhaust gas turbocharger which has a compressor arranged in the intake tract and a turbine arranged in the exhaust tract. The exhaust gas can flow out of the cylinders, flow into the exhaust tract via the turbine and then flow through the exhaust tract. The turbine can be driven by the exhaust gas flowing through the exhaust tract. The compressor can be driven by the turbine, in particular via a shaft of the exhaust gas turbocharger. By driving the compressor, the fresh air flowing through the intake tract can be compressed by means of the compressor. For example, a plurality of components are arranged in the exhaust tract, which components are designed as respective exhaust gas aftertreatment devices or exhaust gas aftertreatment elements, that is to say as exhaust gas aftertreatment components for aftertreatment of the exhaust gas. In the flow direction of the exhaust gas of the internal combustion engine (engine exhaust gas) flowing through the exhaust tract, the components are arranged in succession and are thus connected in series or in series with one another. A first of the components is, for example, an oxidation catalyst, in particular a diesel oxidation catalyst (DOC). Furthermore, the first component can be a nitrogen oxide storage catalyst (SOC), or the first component can have such a nitrogen oxide storage catalyst and / or an oxidation catalyst, in particular a diesel oxidation catalyst. A second of the components may be an SCR catalyst, or the second component comprises such an SCR catalyst. A third of the components can be embodied as a particle filter or comprise such a particle filter. The particulate filter is, for example, a diesel particulate filter (DPF). A fourth of the components can be, for example, a second SCR catalyst or comprise such a second SCR catalyst. Alternatively or additionally, the fourth component can comprise an ammonia rejection catalyst (ASC) or be designed as such an ammonia rejection catalyst (ASC). In the flow direction of the engine exhaust gas flowing through the exhaust tract, the second component is arranged downstream of the first component, the third component is arranged downstream of the second component and the fourth component is arranged downstream of the third component.The drive device can comprise a metering device, by means of which an in particular liquid reducing agent can be introduced into the exhaust tract and, in the process, for example into the engine exhaust gas flowing through the exhaust tract at a first introduction point. The reducing agent is preferably an aqueous urea solution which can provide ammonia which, in the case of a selective catalytic reduction, can react with nitrogen oxides possibly present in the exhaust gas to form water and nitrogen. This selective catalytic reduction can be catalytically effected and / or supported by the respective SCR catalyst. In the flow direction of the engine exhaust gas of the internal combustion engine flowing through the exhaust tract, the first introduction point is arranged, for example, upstream of the second component and downstream of the first component, wherein the second component is arranged downstream of the first component. For example, the fourth component is arranged downstream of the third component, wherein the third component is arranged downstream of the second component and upstream of the fourth component. For example, the exhaust tract has a mixing chamber in which the reducing agent introduced into the exhaust gas at the first introduction point can advantageously be mixed with the exhaust gas, wherein for example the mixing chamber can be arranged upstream of the second component and for example downstream of the first component.The exhaust tract and thus the drive device and the motor vehicle also comprise the burner 10, by means of which, as will be explained in more detail below, at least one of the components, for example the second component and / or the third component and / or the fourth component, can be heated and / or kept warm quickly and efficiently, wherein the at least one component is arranged in the exhaust tract, in particular downstream of the burner 10. The aforementioned first introduction point is also referred to as a first introduction point. The burner 10 can combust a mixture, in particular forming a flame, resulting in a burner exhaust gas of the burner 10, which provides the burner exhaust gas. For example, the burner exhaust gas or the flame can be introduced into the exhaust tract at a second introduction point, that is to say into an exhaust gas duct of the exhaust tract through which the exhaust gas (engine exhaust gas) can flow. This means that the burner 10 is arranged at the second introduction point. For example, the second introduction point is arranged upstream of the second component and upstream of the third component and upstream of the fourth component and downstream of the first component. In other words, for example, the burner 10 is arranged upstream of the second component and upstream of the third component and upstream of the fourth component and downstream of the first component. Alternatively, it is conceivable for the burner 10 or the second introduction point to be arranged upstream of the first component and in particular downstream of the turbine. Thus, for example, the turbine is arranged upstream of the first component. The aforementioned mixture to be burned in the burner 10 or by means of the burner 10 comprises air and a preferably liquid fuel. For example, in the embodiment shown in the figures, the fuel mentioned above is used as the fuel. Alternatively or additionally, at least a portion of the air used for the burner 10 and for forming the mixture can originate from the intake tract or from an air supply path provided separately from the intake tract.For example, a fuel supply path is provided, which is or can be connected fluidically to the burner 10 on the one hand and fluidically to a fuel line on the other hand. The fuel line can be flown through by the fuel from the tank to the injectors or to the fuel distribution element. In particular, the fuel supply path is fluidically connected to the fuel line at a first connection point, wherein the first connection point is arranged downstream of the low-pressure pump and upstream of the high-pressure pump in the flow direction of the fuel flowing from the tank to the fuel distribution element or to the respective injector. At the first connection point, at least a portion of the fuel, in particular liquid fuel, flowing through the fuel line can be branched off from the fuel line and introduced into the fuel supply path. The fuel introduced in the fuel supply path may flow through the fuel supply path and is guided as the fuel by means of the fuel supply path to and in particular into the burner 10. The fuel supply path may alternatively provide an electric fuel pump provided separately from the low pressure pump and the high pressure pump, the electric fuel pump delivering fuel from the tank to the burner 10. In this case, for example, a first valve element is arranged in the fuel supply path, by means of which valve element an amount of the fuel flowing through the fuel supply path and thus to be supplied to the burner 10 can be adjusted. In this case, for example, an electronic computing device, also referred to as a control unit, is provided, by means of which the first valve element can be actuated, so that the quantity of fuel flowing through the fuel supply path and to be supplied to the burner 10 can be adjusted, in particular regulated, by means of the control unit via the first valve element.Furthermore, the air supply path is provided, via which or by means of which the burner 10 can be supplied or is supplied with the air for forming the mixture, which is also referred to as burner mixture. This means that the air from which the mixture is formed can flow through the air supply path. In this case, a pump, also referred to as an air pump, for example, is arranged in the air supply path, by means of which pump the air can be conveyed through the air supply path and thus can be conveyed towards the burner 10. For example, the fuel pump is used, by means of which the fuel is conveyed through the fuel supply path and is thus conveyed to the burner 10. The fresh air introduced into the air supply path can flow through the air supply path as the air for forming the mixture and is conducted by means of the air supply path to and in particular into the burner 10. In this case, for example, a second valve element is arranged in the air supply path, by means of which valve element an amount of the air, which is used to form the mixture and flows through the air supply path and thus through the burner 10, can be adjusted. In this case, for example, the control unit is designed to actuate the second valve element, with the result that, for example, the quantity of air which is used to form the mixture and which flows through the air supply path and is thus to be supplied to the burner 10 can be adjusted, in particular regulated, by means of the control unit via the second valve element.In the following, when air is mentioned, unless otherwise indicated, this is to be understood as meaning the air used to form the mixture.As can be seen from FIG. 1, the burner 10 has a combustion chamber 12 in which the air, which is supplied to the burner 10 and is also referred to as burner air and from which the mixture is formed, and the mixture comprising liquid fuel supplied to the burner 10 are to be ignited and thereby burnt, that is to say is ignited and thereby burnt during operation of the burner 10. For this purpose, for example, an ignition device, in particular an electrically operable ignition device, which is in particular designed as a spark plug or glow plug or glow plug and can be part of the burner 10, for example, is provided. At least one ignition spark can be generated with the ignition device, in particular using electrical energy or electrical current in the combustion chamber 12. The mixture in the combustion chamber 12 is ignited by means of the ignition spark and is subsequently burned, in particular with provision of the burner exhaust gas and / or with provision of the mentioned flame. By means of the burner exhaust gas or by means of the flame, for example, the engine exhaust gas flowing through the exhaust tract can be heated and / or kept warm quickly and efficiently, so that by means of the heated and / or kept warm engine exhaust gas, which flows through the second component, the third component and the fourth component, for example, at least the second component can be heated and / or kept warm quickly and efficiently.The burner 10 has a chamber element 14 designed as a solid body. The combustion chamber 12 is delimited, in particular directly, by the chamber element 14, in particular by an inner-circumferential lateral surface 16 of the chamber element 14.The burner 10 has a first, inner swirl chamber 18, through which a first part of the air, also referred to as burner air, which is supplied to the burner 10 and used for forming the mixture, can flow or is flowed and brings about a first swirling flow of the first part of the air, and is therefore designed for bringing about a first swirling flow of the first part of the air. This is to be understood in particular as meaning that the first part flows in a swirling manner through at least one first subregion of the swirl chamber 18 and / or flows out of the swirl chamber 18 in a swirling manner and / or flows in a swirling manner into and thus in the combustion chamber 12. The inner swirl chamber 18 has, in particular precisely, a first outflow opening 20, through which the first part of the air can flow in a first passage direction of the outflow opening 20 and thus in a first flow direction coinciding with the first passage direction, or through which the air can flow during the aforementioned operation. The first direction of passage and thus the first direction of flow are illustrated by an arrow 22. The first part of the air can be discharged from the inner swirl chamber 18 via the first outflow opening 20 and can in particular be introduced into the combustion chamber 12. This means that the first part of the air can flow out of the inner swirl chamber 18 via the first outflow opening 20. Furthermore, the burner 10 comprises an introduction element, not shown in the figures, in the present case in the form of an injection element through which the liquid fuel, which is supplied to the burner 10, can flow or is flown. The introduction element preferably has one, in particular a plurality of, outlet openings, also referred to as injection openings, through which the fuel supplied to the introduction element can flow, wherein the fuel flowing through the respective outlet opening flows out of the introduction element, in particular as a whole. For example, the respective outlet opening is designed as an in particular round bore. The fuel can flow through the respective outlet opening, for example, along a passage direction, so that the fuel flowing through the introduction element can be or can emerge from the introduction element via the respective outlet opening and can be injected, in particular directly, into the inner swirl chamber 18 and can thereby be introduced. Preferably, the further direction of passage is slightly inclined to the axial direction of the combustion chamber 12, the axial direction of which coincides, for example, with the aforementioned first direction of passage (arrow 22). The inner swirl chamber 18, the axial direction of which runs perpendicular to the radial direction of the swirl chamber 18, the axial direction of which runs perpendicular to the radial direction of the swirl chamber 18, is also referred to as the first inner swirl chamber. Furthermore, for example, the axial direction of swirl chamber 18, the radial direction of which runs perpendicular to the axial direction of swirl chamber 18, coincides with a burner longitudinal axis of burner 10, which extends, for example, along its burner longitudinal axis in an elongate manner. In particular, the swirl chamber 18 and / or the combustion chamber 12 can be designed to be rotationally symmetrical, for example, with respect to the burner longitudinal axis. In particular, the axial direction of the swirl chamber 18 coincides with the first flow direction (passage direction) illustrated by the arrow 22. The introduction element is designed in particular to eject the fuel from the outlet openings in a clocked manner and thus to inject it in a clocked manner into the swirl chamber 18, in particular directly, in particular to eject it onto a first surface 24, which directly delimits the swirl chamber 18 in particular in the radial direction of the swirl chamber 18 and is designed as an inner-circumferential lateral surface. In other words, the swirl chamber 18 is directly delimited at least partially, in particular at least predominantly and thus at least to an extent of more than half or else completely, by the first surface 24, which in the present case is a lateral surface on the inner circumference side and is concavely arched in the process.The respective further direction of passage of the respective outlet opening coincides with a respective further direction of flow along which or into which the fuel can flow through the respective outlet opening and thus can flow out of the introduction element. The fuel can be injected from the introduction element via the respective outlet opening, in particular forming a respective fuel jet, and thereby in particular injected directly into the swirl chamber 18. For example, the respective fuel jet, the longitudinal central axis of which coincides, for example, with the respective further passage direction or with the respective further flow direction, is at least substantially of lobe-shaped and / or conical design. In addition, the introduction element has a longitudinal direction or longitudinal extent or longitudinal extent direction which runs parallel to the first passage direction and thus parallel to the first flow direction and parallel to the axial direction of the inner swirl chamber 18, in particular coincides with the first passage direction 22 and thus with the first flow direction and thus in particular coincides with the axial direction of the swirl chamber 18. For example, the respective further passage direction runs perpendicular or, in the present case, obliquely to the first passage direction 22 and thus to the first flow direction and to the axial direction of the first inner swirl chamber 18 and the first outflow opening 20.The inner swirl chamber 18 is formed or bounded at least partially, in particular at least predominantly and thus at least to an extent of more than half or else completely, by a first structural element 26 of the burner 10, which is also referred to as a component, such that, for example, the first structural element 26 also forms or bounds the first outflow opening 20, in particular directly. Thus, for example, the structural element 28 forms the first surface 24. in the present case, the outflow opening 20 is completely circumferential along its circumferential direction running around the axial direction of the inner swirl chamber 18 and directly delimited by a part of the first surface 24, so that in the present case the outflow opening 20 is completely circumferential along its circumferential direction running around the axial direction of the inner swirl chamber 18 and directly delimited by the first surface 24 and thus the first structural element 26. The first component 26 with its first surface is also referred to as a pre-filmer.The burner 10 furthermore has an outer swirl chamber 28, which surrounds at least one length region and in the present case also the first outflow opening 20 in the circumferential direction of the inner swirl chamber 18, in particular in a completely encircling manner, which circumferential direction runs around the axial direction of the inner swirl chamber 18. In this case, for example, the first structural element 26 has a separating wall 30, which is arranged between the swirl chambers 18 and 28 in the radial direction of the inner swirl chamber 18 and thus in the radial direction of the outer swirl chamber 28, the radial direction of which coincides with the radial direction of the swirl chamber 18. Thereby, the swirl chambers 18 and 28 whose axial directions coincide with each other are separated from each other in the radial direction of the swirl chambers 18 and 28 by the partition wall 30. The axial direction of the swirl chamber 18 coincides with the axial direction of the swirl chamber 28, the radial direction of which is perpendicular to the axial direction of the swirl chamber 18, the radial direction of the swirl chamber 18 coinciding with the radial direction of the swirl chamber 28. A second part of the burner air, which is supplied to the burner 10 and used for forming the mixture, can flow through the outer, second swirl chamber 28 and is designed to bring about a second swirling flow of the second part of the air. This means that the second part of the air flows through the swirl chamber 28 in a swirling manner and / or flows out of the swirl chamber 28 in a swirling manner and / or flows into and thus in the combustion chamber 12 in a swirling manner. In particular, it is provided that the second part of the air flows through at least one second partial region of the outer swirl chamber 28 in a swirling manner and / or flows out of the swirl chamber 28 in a swirling manner and / or flows into and thus in the combustion chamber 12 in a swirling manner.The outer, second swirl chamber 28 has, in particular precisely, a second outflow opening 32 through which the second part of the air flowing through the outer swirl chamber 28 can flow, in particular in a second flow direction, the second flow direction of which, coinciding with the second flow direction, through which the second part of the air flowing through the swirl chamber 28 can flow through the outflow opening 32, coincides in the present case with the axial direction of the swirl chamber 28 and thus with the axial direction of the swirl chamber 18. The second direction of passage coincides with the second direction of flow, along which or into which the second part of the air flowing through the outer swirl chamber 28 flows through or can flow through the outflow opening 32. This means in particular that the first passage direction 22 coincides with the second passage direction and the first flow direction coincides with the second flow direction, so that in the present case the first flow direction, the second flow direction, the first flow direction and the second passage direction coincide and coincide with the axial direction of the swirl chamber 18 and with the axial direction of the swirl chamber 28 and are illustrated by the arrow 22. Thus, the first direction of passage, the first direction of flow, the second direction of passage, and the second direction of flow are illustrated by arrow 22. In the flow direction of the air flowing through the swirl chambers 18 and 28, in particular the outflow openings 20 and 32, the second outflow opening 32 is arranged downstream of the first outflow opening 20 and in this case arranged or connected in series or in series with the first outflow opening 20, such that the second outflow opening 32 can be flowed through by the second part of the air, by the first part of the air and by the fuel. In particular, the first part of the air is already mixed with the fuel in the swirl chamber 18, in particular due to the swirling first flow, in particular with the formation of a partial mixture. The partial mixture can flow through the outflow opening 20 and thus flow out of the swirl chamber 18 and then flow through the second outflow opening 32 and is mixed with the second part of the air, in particular on account of the advantageous, second swirling flow, as a result of which the mixture is processed particularly advantageously, and therefore the partial mixture is mixed particularly advantageously with the second part of the air, as a result of which the mixture is formed.It can be seen that the outer swirl chamber 28 is bounded at least partially, in particular at least predominantly and thus at least to an extent of more than half or else completely, inward in the radial direction of the respective swirl chamber 18, 28 by a second surface 34 of the burner 10, in particular directly. In this case, the first outflow opening 20 is in particular completely circumferential along its circumferential direction running around the axial direction of the swirl chamber 28, and is directly bounded here by a part of the first surface 24 and the second surface 34. The part of the first surface 24 delimiting the first outflow opening 20 is also referred to as a first surface part, and the part of the second surface 34 delimiting the first outflow opening 20 is also referred to as a second surface part. In the present case, the second surface 34 is an outer circumferential surface and is thus convexly curved. The second surface 34 is a surface of the partition wall 30 of the burner 10.It can also be seen that the outer swirl chamber 28 is bounded at least partially, in particular at least predominantly and thus at least to an extent of more than half or else completely, outwards in the radial direction of the respective swirl chamber 18, 28 by a third surface 35 of the burner 10, in particular directly. In this case, the second outflow opening 32 is in particular completely circumferential along its circumferential direction running around the axial direction of the swirl chamber 28, and is directly delimited by a part of the third surface 35. The part of the third surface 35 delimiting the outflow opening 32 is also referred to as a third surface part. In the present case, the third surface 35 is an inner circumferential surface and is thus concavely arched. The third surface 35 is a surface of a second component 36 of the burner 10. This means that, in the radial direction of the respective swirl chamber 18, 28 towards the outside, the outer swirl chamber 28 is at least partially, in particular at least predominantly and thus at least to the extent of more than half or else completely, delimited by the second structural element 36 of the burner 10, in particular directly. In the present case, the first component 26 is arranged at least partially, in particular at least predominantly and thus at least to an extent of more than half or else completely, in the second component 36. The second outflow opening 32 is bounded or formed, respectively, along its circumferential direction running around the axial direction of the respective swirl chamber 18, 28, completely circumferentially by the second structural element 36 and in the process by the second surface part, in particular in the radial direction of the respective swirl chamber 18, 28 toward the outside. Accordingly, the first outflow opening 20 is directly delimited or formed along its circumferential direction so as to be completely circumferential by the first surface part, in particular directly delimited or formed in the outward direction in the radial direction of the respective swirl chamber 18, 28, and is directly delimited or formed along its circumferential direction so as to be completely circumferential by the second surface part, in particular in the inward direction in the radial direction of the respective swirl chamber 18, 28. The respective component 26, 36 is formed as a respective solid body. The chamber element 14 is designed as a solid body. The combustion chamber 12 is at least partially, in particular at least predominantly and thus at least to an extent of more than half or even completely, delimited by the chamber element 14, which is designed as a solid body and is therefore self-rigid and therefore dimensionally stable, in particular directly. The chamber element 14 has the circumferential surface 16 on the inner circumference, by which the combustion chamber 12 is at least partially and directly delimited, in particular in the radial direction of the respective swirl chamber 18, 28 towards the outside.The first inner swirl chamber 18 has a first swirl generating device 38 by means of which the first swirling flow of the first part of the air can be effected or is effected. The second outer swirl chamber 28 has a second swirl generating device 40, by means of which the second swirling flow of the second part of the air can be effected or is effected.The burner 10 also has a closure element 42 which is movable relative to the outflow openings 20 and 32, relative to the chamber element 14 and relative to the structural elements 26 and 36 between at least one closed position and at least one open position O shown in FIG. 1. The closed position is also referred to as the first position, and the open position O is also referred to as the second position. In the closed position, the outflow opening 32 is fluidically blocked by the closure element 42, in particular towards the combustion chamber 12. This means that in the closed position of the closure element 42 the outflow opening 32 is fluidically separated from the combustion chamber 12 by means of the closure element 42. Since, as viewed along the respective flow direction, the outflow opening 32 is arranged downstream of the outflow opening 20, in the closed position of the closure element 42 the outflow opening 20 is also fluidically blocked towards the combustion chamber 12 by means of the closure element 42, so that in the closed position of the closure element 42 the outflow opening 20 is also fluidically separated from the combustion chamber 12 by means of the closure element 42. This means that in the closed position of the closure element 42 by means of the closure element 42 both outflow openings 20 and 32 are fluidically separated from the combustion chamber 12. As a result, no particles or gases, in particular from the engine exhaust gas, which flow into the combustion chamber 12 via combustion chamber openings 43 of the combustion chamber 12 can reach the outflow openings 20 and 32 and settle there. In the open position O, the closure element 42 releases the outflow openings 20 and 32, so that in the open position O both outflow openings 20 and 32 are fluidically connected to the combustion chamber 12.In the exemplary embodiment shown in the figures, the closure element 42 is held on a lever 44, in particular in such a way that the closure element 42 is formed separately from the lever 44 and is held on the lever 44. The lever 44 and with it the closure element 42 are pivotable about a pivot axis S relative to the outflow openings 20 and 32 and relative to the chamber element 14 and relative to the structural elements 26 and 36 between the positions, that is to say between the closed position and the open position O. The pivot axis S extends perpendicular to the axial direction of the respective swirl chamber 18, 28. This means that the respective axial direction of the respective swirl chamber 18, 28 extends perpendicular to a first plane, wherein the pivot axis S extends perpendicular to a second plane, and wherein the first plane and the second plane extend perpendicular to one another. In particular, the pivot axis S intersects neither the swirl chamber 18 nor the swirl chamber 28.In order to be able to ensure a particularly advantageous treatment of the mixture, also referred to as mixture treatment, and thus a particularly advantageous operation of the burner 10, in particular also over a long service life of the burner 10, it is provided in the burner 10 that the closure element 42 slides directly along the first surface part and / or along the second surface part of the first outflow opening 20 at least during its movement from one of the positions into the other position and preferably also during its movement from the other position into the one position and thus slides directly on the first surface part and / or the second surface part. For example, the one position is the open position O, so that the other position is the closed position. It is also conceivable for one position to be the closed position and the other position to be the open position O. Due to the fact that the closure element 42 slides directly along the first surface part and / or the second surface part at least during the movement of the closure element 42 from the one position into the other position and preferably also during the movement of the closure element 42 from the other position into the one position, contaminants are scraped off from the first surface part and / or the second surface part by means of the closure element 42, whereby the first surface part and / or the second surface part of the first outflow opening 20 is cleaned. As a result, an advantageous, in particular advantageously large, flow cross section of the outflow opening 20 and / or 32 through which the respective part of the air can flow can be ensured even over a long service life of the burner 10.For example, the closure element 42 is or is pivotable or pivoted between the positions by at least 90 degrees.FIG. 2 illustrates, by way of example, the position of the closure element 42 shortly before the closing or shortly after the opening. FIGS. 1 and 2 show a first embodiment of the closure element 42. The conical partial region T is formed, for example, by a first part 46 of the closure element 42. The conical sub-region T of the first part 46 is designed in the form of a conical cap, wherein the conical sub-region T is designed to be open in the direction of the first outflow opening 20 and, in the closed position of the closure element 42, bears against the second surface 34, in particular can slide over the second surface 34. Furthermore, the first part 46 has a plug 47 in the interior, wherein the plug 47 has penetrated into the first outlet opening 20 in the closed position of the closure element 42 and bears against the first surface 24, in particular can slide over the first surface 24 in the region of the first outflow opening 20. In the closed position of the closure element 42, it is possible, in particular at a circumferential edge K of the first outflow opening 20, for any soiling or deposits to be removed by overstripping, sliding or bearing of the conical subregion T over the second surface 24 and overstripping, sliding or bearing of the stopper 47 of the first surface 24. The closure element 42 has, for example, a second part 48, wherein, for example, the part 46 and thus the conical partial region T are held by the second part 48. It is conceivable that the first part 46 and thus the conical partial region T are formed separately from the second part 48 and are held on the second part 48. Furthermore, it would be conceivable for the parts 46 and 48 to be formed integrally with one another, and therefore to be formed from a single piece. For example, the first part 46 and thus the conical partial region T are placed on the second part 48. For example, the second part 48 is a closure flap, also referred to simply as a flap. It is conceivable that the first part 46 and thus the conical partial region T are held on the second part 48 so as to be movable to a limited extent. When the closure element 42 is moved at least from the one position into the other position, the conical partial region T scrapings along the first surface part and / or the second surface part, as a result of which contaminants, such as soot particles, for example, are scraped off from the first surface part and / or the second surface part, in particular from the first outflow opening 20.This removal of dirt, in particular at the first outflow opening 20, is an important component of the functionality of the burner 10. However, the closing of the closure element 42 can take a longer period of time than the engine exhaust gas can penetrate from the exhaust tract via the burner openings 43 into the combustion chamber 12, as a result of which, for example, particles can settle out in particular in the region of the circumferential edge K of the first outflow opening 20 and at least interfere with or prevent a fine distribution in particular of the fuel injected into the inner swirl chamber 18 into the combustion chamber 12. For proper operation of the burner 10, a fine distribution of the fuel with as small droplets of the fuel as possible in the combustion chamber 12 is particularly importantIn the first embodiment shown in FIGS. 1 and 2, the conical sub-region T is free of through-openings and thus free of slots.FIG. 3 shows a schematic side view of a second embodiment of the closure element 42, in particular of the conical subregion T. In the second embodiment, the conical subregion T has a plurality of slots 50 designed as through openings. The slots 50 are arranged in succession in the circumferential direction of the conical sub-region T and are spaced apart from one another and in particular uniformly distributed. In the closed position of the closure element 42, the circumferential direction of the conical sub-region T runs around the axial direction of the respective swirl chamber 18, 28.It can also be seen from FIGS. 2 and 3 that the conical sub-region T widens in the direction of the swirl chambers 18 and 28 in the closed position of the closure element 42. In reverse terms, it is provided that in the closed position of the closure element 42 the conical sub-region T narrows in the respective flow direction illustrated by the arrow 22.The chamber element 14 has a recess 52 when the chamber element 14 is viewed alone, which opens into the combustion chamber 12 when the chamber element 14 is viewed alone. In the open position O, the lever 44 and the closure element 42 are each arranged at least partially in the recess 52. In other words, in the open position O, at least respective partial regions of the lever 44 and of the closure element 42 are arranged in the recess 52 and outside the combustion chamber 12. In the closed position, the partial regions of the lever 44 and of the closure element 42 are arranged in the combustion chamber 12 and outside the recess 52. As a result, advantageous flow conditions in the combustion chamber 12 can be ensured, in particular in the open position O.It can be seen particularly well from FIG. 1 that the conical sub-region T protrudes from a wall region W of the closure element 42 adjoining the conical sub-region T. In this case, the wall region W of the closure element 42 is formed, for example, by the second part 48. In this case, it is provided in particular that, in the closed position of the closure element 42, the wall region W extends in a third plane, also referred to as the plane of extent, which, in the closed position, runs perpendicular to the axial direction of the respective swirl chamber 18, 28. For example, the third plane in the closed position runs parallel to the first plane or the third plane coincides with the first plane in the closed position.List of reference characters10 Burner 12 Combustion chamber 14 Chamber element 16 Inner-circumferential-side lateral surface 18 Inner swirl chamber 20 First outflow opening 22 First passage direction 24 First surface 26 First structural element 28 Outer swirl chamber 30 Partition wall 32 Second outflow opening 34 Second surface 35 Third surface 36 Second structural element 38 First swirl-generating device 40 Second swirl-generating device 42 Closure element 43 Combustion chamber openings 44 Lever 46 First part 47 Plug 48 Second part 50 Slot 52 Recess K Edge O Open position S Pivot axis T Conical subregion W Wall region

Claims

Burner (10) for an exhaust tract through which exhaust gas from an internal combustion engine of a motor vehicle can flow, having: - a combustion chamber (12) in which a mixture comprising air and a fuel can be ignited and thereby burnt; - an inner swirl chamber (18) through which a first part of the air can flow, which has a first swirl generating device (38), by means of which a swirling flow of the first part of the air can be effected, and a first outflow opening (20), through which the first part of the air flowing through the inner swirl chamber (18) can flow, via which the first part of the air can be discharged from the inner swirl chamber (18); an outer swirl chamber (28) which surrounds at least one longitudinal region of the inner swirl chamber (18) in the circumferential direction of the inner swirl chamber (18) and through which a second part of the air can flow, which has a second swirl generating device (40), by means of which a swirling flow of the second part of the air can be effected, and a second part of the air which flows through the outer swirl chamber (28), and a second outflow opening (32), through which the first part of the air which flows through the inner swirl chamber (18) and the first outflow opening (20) can flow, via which the parts of the air can be introduced into the combustion chamber (12); and - a closure element (42) which is movable relative to the outflow openings (20, 32) between at least one closed position, which closes at least one of the outflow openings (20, 32), as the first position and at least one open position (O), which opens up the at least one outflow opening (20, 32), as the second position; characterized in that the closure element (42) slides, at least during its movement from one of the positions into the other position, along the surface (24, 34) of the burner (10), which surface directly and at least partially delimits the first outflow opening (20).Burner (10) according to claim 1, characterised in that the closure element (42) has a first part (46) with a conical partial region (T) which slides along the second surface (34) of the burner (10) at least during the movement of the closure element (42) from the one position into the other position.Burner (10) according to claim 1 or 2, characterised in that the first part (46) of the closure element (42) has a plug (47) which, at least during the movement of the closure element (42) from the one position into the other position, penetrates into the first outflow opening (20) and slides along the first surface (24) of the burner (10).Burner (10) according to Claim 2 or 3, characterized in that, in the closed position, the conical subregion (T) widens in the direction of the swirl chambers (18, 28).Burner (10) according to one of Claims 2 to 4, characterized in that the conical subregion (T) projects from a wall region (W) of the closure element (42) adjoining the subregion (T).Burner (10) according to one of Claims 2 to 5, characterized in that the conical subregion (T) has at least one slot (50).Burner (10) according to Claim 6, characterized in that the conical subregion (T) has a plurality of slots (50), namely the at least one slot (50) and at least one further slot (50).Burner (10) according to Claim 7, characterized in that the slots (50) are arranged uniformly distributed in the circumferential direction of the conical sub-region (T).Burner (10) according to one of the preceding claims, characterized in that the closure element (42) is pivotable between the positions about a pivot axis (S) relative to the outflow openings (20, 32).Motor vehicle, having an internal combustion engine, by means of which the motor vehicle can be driven, and having an exhaust tract through which exhaust gas from the internal combustion engine can flow, which exhaust tract has at least one burner (10) according to one of the preceding claims.

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