Method for operating a burner for a motor vehicle

Abstract

The invention relates to a method for operating a burner (10) for an exhaust tract through which exhaust gas can flow, in which the burner (10) has a combustion chamber (12) in which a mixture comprising air and a fuel is to be burned. The burner (10) comprises a channel (18) through which at least part of the air can flow and which has an outflow opening (22) via which at least part of the air can be discharged from the channel (18) and fed to the combustion chamber (12). The burner (10) comprises a closure element (30) which is movable relative to the outflow opening (22) between at least one closed position (ST) closing the outflow opening (22), as a first position in which the channel (18) is fluidically separated from the combustion chamber (12), and at least one open position exposing the one outflow opening (22), as a second position in which the channel (18) is fluidically connected to the combustion chamber (12).

Description

The invention relates to a method for operating a burner for an exhaust tract through which exhaust gas of an internal combustion engine of a motor vehicle can flow, according to the preamble of patent claim 1.Such a method for operating a burner for an exhaust tract through which exhaust gas from an internal combustion engine of a motor vehicle can flow is already known from DE 10 2021 001 580 A1, for example. In the method, the burner has a combustion chamber in which a mixture is to be ignited and thereby burned, the mixture comprising air and a fuel. In the method, the burner has at least one duct through which at least part of the air can flow, which duct has an outflow opening through which at least the part of the air flowing through the duct can flow, via which opening at least the part of the air can be discharged from the duct and fed to the combustion chamber. In the method, the burner also has a closure element which is movable relative to the outflow opening between at least one closed position and at least one open position. The closed position is also referred to as a first position, and the open position is also referred to as a second position. In the closed position, the closure element closes the outflow opening, as a result of which the channel is fluidically separated from the combustion chamber in the closed position. In the open position, the closure element opens up the outflow opening, so that in the open position the channel is fluidically connected to the combustion chamber via the outflow opening.Furthermore, DE 10 2019 008 956 A1 discloses an exhaust system for an internal combustion engine.It is the object of the present invention to further develop a method of the type mentioned at the beginning in such a way that particularly advantageous operation of the burner can be realized, in particular, even over a long service life of the burner.This object is achieved by a method having the features of claim 1. Advantageous embodiments with expedient developments of the invention are specified in the other claims.In order to further develop a method of the type specified in the preamble of claim 1 in such a way that particularly advantageous operation of the burner can be realized, in particular, even over a long service life of the burner, it is provided according to the invention that at least one value is determined by means of an electronic computing device, in particular of the motor vehicle, which characterizes a sum of operating states in which the internal combustion engine carries out a load jump while the closure element is in the open position. In addition, the method provides that at least one component of the motor vehicle is operated as a function of the value. For example, the component is or comprises the burner, so that, for example, the burner is operated as a function of the value. It is furthermore conceivable for the component to be a component different from the burner and / or to comprise a component different from the burner, with the result that, for example, the component different from the burner is operated as a function of the value.The background of the invention is in particular that, as a result of a load jump, in particular as a result of a full load jump of the internal combustion engine, the internal combustion engine comes into such an operation, operating state or operating point that, as a result of the load jump, a large amount of particles, such as soot particles, for example, can be contained in the exhaust gas of the internal combustion engine, which is also referred to as engine exhaust gas. These particles contained in the exhaust gas of the internal combustion engine, also referred to as engine exhaust gas, can flow through the outflow opening and thus flow into the duct via combustion chamber openings into the combustion chamber and from or out of the combustion chamber, in particular when the closure element is open, i.e. when the closure element is in the open position, in order subsequently to negatively affect, or clog and / or plug, for example the outflow opening and / or the duct and / or at least one burner component of the burner. This is the case in particular when the burner is deactivated in the respective operating state. Thus, it is provided, for example, that in the respective operating state the internal combustion engine executes a load jump, while the closure element is in the open position and, in particular, the burner is deactivated at the same time. The inflow of the particles, preferably embodied as soot particles, via the exposed outflow opening in the channel is also referred to as soot introduction. Thus, in the method according to the invention, it is provided that the operating states in which soot entry into the channel can occur due to the open closure element and due to the respective load jump are summed up, which is characterized, i.e. indicated, by the value also referred to as the summed value. The respective operating state, i.e. the respective load jump, of success, while the closure element is opened and in particular the burner is deactivated, is thus an event in which or as a result of which a risk is very high that soot entry occurs in the channel. The events are summed by means of the electronic computing device, whereby, for example, the value is formed which characterizes a sum of the events. Since the at least one component is operated as a function of the value, a measure can be taken, effected or carried out, for example, wherein the measure counteracts the introduction of soot into the channel and / or an excessive introduction of soot into the channel can be avoided, for example.The operation, i.e. the measure, comprises, for example, that while the internal combustion engine is at a standstill, i.e. while the internal combustion engine is deactivated, so that no combustion processes proceed in the internal combustion engine, air is conducted through the duct, in particular actively conveyed through it, in particular while the closure element is open, thus is in the open position. This causes an air flow through the channel, whereby, for example, any particles that have flowed into the channel, such as soot particles, for example, can be conveyed out of the channel via the exposed outflow opening. In other words, the channel can thereby advantageously be blown free. Since this purging is carried out while a fired operation of the internal combustion engine is not taking place, i.e. while no combustion processes take place in the internal combustion engine and thus while the internal combustion engine is not providing its engine exhaust gas, a soot entry into the duct can be avoided during the purging.The invention is based in particular on the following findings and considerations: in order to be able to realize particularly low-emission operation of the internal combustion engine, in particular during a cold start of the internal combustion engine, and thus to be able to avoid excessive emissions, in particular cold start emissions, of the internal combustion engine, the burner is used. This is advantageous in particular when the internal combustion engine is designed as a diesel engine. By means of the burner, at least one exhaust gas component which is arranged in the exhaust tract and can thus be flown through by the exhaust gas of the internal combustion engine and is designed, for example, for aftertreatment of the exhaust gas, can be effectively and efficiently heated and / or kept warm and can thus be kept, for example, in an advantageous temperature range in which the exhaust gas can be advantageously after-treated by means of the exhaust gas component. The exhaust gas component is or comprises, for example, at least one in SCR catalyst, which can be catalytically active for an SCR (selective catalytic reduction), in particular in such a way that the SCR can be catalytically activated and / or supported by means of the SCR catalyst. Alternatively or additionally, the exhaust gas component can comprise at least one particle filter, for example, or the exhaust gas component can be at least one particle filter, wherein the particle filter can be designed as a diesel particle filter (DPF), for example. By means of the burner, the exhaust gas component can be heated and / or kept warm without causing appreciable emissions as a result. The burner is usually deactivated when the internal combustion engine is operated with a sufficient load and in particular in its traction mode. However, if, for example, the internal combustion engine is in its overrun mode, in which a fired operation of the internal combustion engine is omitted, which in its non-fired operation does not provide the engine exhaust gas, the burner can be operated in order thereby to keep the exhaust gas component warm and / or heat up and to avoid excessive cooling out or cooling down of the exhaust gas component. For example, the internal combustion engine is in its non-fired operation and / or coasting operation when the motor vehicle is travelling downhill. A transfer of the internal combustion engine from its coasting mode into its traction mode or from the non-fired mode into the fired mode is associated with a load jump of the internal combustion engine, for example. As a result of the load surge or an instationary operation, a high amount of particles, in particular soot particles, can be contained in the engine exhaust gas, wherein these particles can pass into the duct, for example, via the combustion chamber and the outflow opening. This can now be avoided by the closure element. If, however, for example, the load jump takes place at a first point in time, the closure element can be opened, in particular continuously, for example from the first point in time to a subsequent second point in time and only reach the closed position at the second point in time, in particular for example when a movement of the closure element from the open position into the closed position is started at the first point in time or at a third point in time lying between the first point in time and the second point in time. The movement of the closure element from the open position into the closed position is subject to a certain hysteresis, so that the closed position takes a certain period of time, for example, at the second point in time. Then, an amount of the particles may optionally flow into the passage, such that an amount of particles located in the passage may increase as the operating or life time of the internal combustion engine increases. The method according to the invention now makes it possible to add up load jumps that can result in a soot entry in the channel. By operating the at least one component as a function of the value, soot introduction into the channel can be counteracted and / or excessive soot introduction into the channel can be avoided. Since the operation of the component, as described above, can comprise air being passed through the channel, in particular actively conveyed through it, in particular when the closure element is open, an interior of the burner can be blown free thereby, for example, and thus freed of any particles that have penetrated into the channel. This makes it possible to avoid undesired impairment of the burner by particles which have flowed into the duct.Further advantages, features and details of the invention will become apparent from the following description of a preferred exemplary embodiment 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 single figure 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 the single FIG. 1 a schematic rear view of a burner for an exhaust tract through which the exhaust gas of an internal combustion engine of a motor vehicle can flow.FIG. 1 shows a schematic sectional view of a burner 10 for an exhaust tract through which exhaust gas from an internal combustion engine of a motor vehicle, which is also referred to simply as a vehicle, can flow, which exhaust tract is also referred to as an exhaust system. The exhaust gas of the internal combustion engine is also referred to as engine exhaust gas. The internal combustion engine is preferably designed as a diesel engine. For example, at least one exhaust gas component is arranged in the exhaust tract, through which the exhaust gas can flow. In the following, when the exhaust gas is mentioned, this is to be understood as meaning the engine exhaust gas of the internal combustion engine unless otherwise stated. For example, the exhaust gas component is or is involved in at least one exhaust gas aftertreatment element, by means of which the exhaust gas can be post-treated. By means of the burner 10, the exhaust gas component can be heated and / or kept warm quickly and efficiently, wherein the exhaust gas component is arranged downstream of the burner 10 in the exhaust tract. The burner 10 can combust a mixture, also referred to as a burner mixture, in particular with the formation of a flame, resulting in a burner exhaust gas of the burner 10, which provides or can provide the burner exhaust gas. For example, the burner exhaust gas or the flame can be introduced into the exhaust tract at an introduction point, that is to say into an exhaust gas duct of the exhaust tract through which the engine exhaust gas can flow. This means that the burner 10 is arranged at the introduction point. For example, the introduction point is arranged upstream of the exhaust gas component. In other words, the burner 10 is arranged upstream of the exhaust gas component. The aforementioned mixture to be burned in the burner 10 or by means of the burner 10, which is also referred to as burner mixture, comprises air and a preferably liquid fuel. For example, a preferably liquid fuel is used as the fuel, by means of which, for example, the internal combustion engine can be operated in its fired operation. If the term air is used below, unless otherwise stated, the air, which is also referred to as burner air and from which the aforementioned burner mixture is formed, is to be understood. For example, the air can be supplied to the burner.The burner 10 has a combustion chamber 12 which is bounded, in particular directly, by a chamber element 14 of the burner 10 which is embodied as a solid body. In the combustion chamber 12, the mixture can be burnt, in particular ignited and burnt. In order to ignite the mixture, in particular in the combustion chamber 12, and to burn it as a result, the burner 10 has, for example, an ignition device 16 which is in particular designed as a spark plug or glow plug or glow pin and can be operated in particular electrically. By means of the ignition device 16, at least one ignition spark can be generated in the combustion chamber 12, in particular using electrical energy or electrical current, by means of which spark the mixture in the combustion chamber 12 can be ignited and subsequently burned, in particular while providing the burner exhaust gas and / or the flame mentioned. The burner exhaust gas and / or the flame enters via combustion chamber openings 17 in the chamber element 14 from the combustion chamber 12 into the exhaust gas duct of the exhaust tract through which the engine exhaust gas can flow. By means of the burner exhaust gas or by means of the flame, for example, the exhaust gas flowing through the exhaust tract, that is to say the exhaust gas flowing through the exhaust gas duct, can be heated and / or kept warm quickly and efficiently, with the result that the exhaust gas component can be heated and / or kept warm quickly and efficiently by means of the heated and / or kept warm exhaust gas (engine exhaust gas) which flows through the exhaust gas component, for example.The burner 10 has a duct 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 in a relational manner. The channel 18 has a first, inner swirl chamber 20 of the burner 10, so that the first part of the burner air can flow through or is flowed through the inner swirl chamber 20. By means of the swirl chamber 20, a first swirling flow of the first part of the air can be effected. The inner swirl chamber 20 and thus the duct 18 has, in particular precisely, a first outflow opening 22, via which the first part of the air can be discharged from the swirl chamber 20 and thus into the duct 18 and can be fed to the combustion chamber 12. The outflow opening 22 can thus be flown through by the first part of the air. In particular, the first part of the air can be discharged from the swirl chamber 20 and the duct 18 into the combustion chamber 12 via the first outflow opening 22. Furthermore, the burner 10 comprises an introduction element 24, through which the liquid fuel which is supplied to the burner 10 can flow. The introduction element 24 has outlet openings through which the fuel can flow. By means of the introduction element 24, the fuel can be injected, in particular directly, into the swirl chamber 20 and thus the duct 18 and thus introduced together with the first part of the air into the combustion chamber 12.The burner 10 furthermore has a second outer swirl chamber 26 which surrounds at least one length region and in the present case the first outflow opening 22 in the circumferential direction of the inner swirl chamber 20 running around the axial direction of the inner swirl chamber 20, in particular in a completely encircling manner. For example, the outer second swirl chamber 26 is arranged in a second duct of the burner 10, wherein, for example, a second part of the burner air can flow through or is able to flow through the second duct and thus the second outer swirl chamber 26. The outer, second swirl chamber 26 has, in particular precisely, a second outflow opening 28, through which the second part of the air flowing through the outer swirl chamber 26 can flow, which can also be through which the first part of the air flowing through the channel 18 and thus the swirl chamber 20 can flow and the fuel introduced into the channel 18 by means of the introduction element 24. Thus, in the flow direction of the air flowing through the swirl chambers 20 and 26, the outflow opening 28 is arranged downstream of the outflow opening 22. In particular, the first part of the air is advantageously mixed with the fuel, in particular to form a partial mixture, in particular due to the swirling first flow of the first part of the air already in the swirl chamber 20. The partial mixture can flow through the outflow opening 22 and thus flow out of the swirl chamber 20 and then flow through the second outflow opening 28 and is mixed with the second part of the air and flow into the combustion chamber 12. By means of the swirl chamber 26, a second swirling flow of the second part of the burner air can be effected, wherein, owing to the swirling second flow of the second part of the air, the part mixture is particularly advantageously mixed with the second part of the air, as a result of which the mixture is particularly advantageously processed.It can be seen from FIG. 1 that the burner 10 also has a closure element 30, which can be pivoted about a pivot axis S relative to the outflow openings 22 and 28 and relative to the chamber element 14 between at least one closed position and at least one open position and can thereby be moved. The closed position is also referred to as a first position, and the open position is also referred to as a second position. In the closed position of the closure element 30 shown in FIG. 1 and designated ST, the outflow opening 28 and thus the outflow opening 22 are fluidically blocked by means of the closure element 30, as a result of which, in the closed position ST, the outflow openings 28 and 22 are fluidically separated from the combustion chamber 12 by means of the closure element 30. In the open position, the closure element 30 releases the outflow openings 22 and 28, so that in the open position the aforementioned channels and thus the swirl chambers 20 and 26 are fluidically connected to the combustion chamber 12 via the outflow openings 22 and 28.In the following, a method for operating the burner 10 is explained with reference to FIG. 1. In the method, at least one value is determined by means of an electronic computing device 32, in particular of the motor vehicle, which is illustrated particularly schematically in FIG. 1, which characterizes a sum of operating states in which the internal combustion engine executes a load jump while the closure element 30 is in the open position and in particular while the burner 10 is deactivated. In other words, the value characterizes a number, i.e. a frequency, with which the operating states have occurred. Again in other words, the value characterizes a set, i.e. a frequency of the operating states mentioned. In the method, at least one component of the motor vehicle is operated as a function of the value. This means in particular that at least one function of the component is carried out as a function of the value. For example, the at least one function is carried out when the value exceeds a threshold value, which is predetermined or predeterminable, for example.The component is or comprises, for example, a component which is different from the burner 10 and is additionally provided for this purpose. It is furthermore conceivable for the said component to comprise the burner 10 or to be the burner 10. It is conceivable that the operation of the component, and thus the mentioned at least one function, comprises air being conducted through the channel 18, in particular actively conveyed through it, for example by means of a pump, in particular while the closure element 30 is in the open position and in particular while a fired operation of the internal combustion engine is not occurring, that is to say while no combustion processes are running in the internal combustion engine. The passing of the air through the channel 18 ceases to result in, for example, the passing of the fuel through the channel 18, further comprising, for example, the operation of the component, and thus the at least one function of air also being passed through the second channel, in particular actively conveyed, for example by means of a further pump or at least the pump, in particular while the closure element 30 is in the open position and very particularly while the burner 10 is deactivated and in particular remaining absent during the fired operation of the internal combustion engine. As a result, particles, such as soot particles, for example, that may have penetrated into the channels can be transported out of the channels, in particular blown out, so that, for example, the channels can be blown free. Since the at least one function is performed while the fired operation of the internal combustion engine is omitted, it is possible to prevent particles from entering the passages via the outflow openings 22 and 28.List of reference characters10 Burner 12 Combustion chamber 14 Chamber element 16 Ignition device 17 Combustion chamber openings 18 Channel 20 Inner swirl chamber 22 First outflow opening 24 Introduction element 26 Outer swirl chamber 28 Second outflow opening 30 Closure element 32 Electronic computing device S Pivot axis ST Closed positionReferences included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedDE 10 2021 001 580 A1

[0002] DE 10 2019 008 956 A1

[0003]

Claims

Method for operating a burner (10) for an exhaust tract through which exhaust gas from an internal combustion engine of a motor vehicle can flow, wherein the burner (10) has: - a combustion chamber (12) in which a mixture comprising air and a fuel can be ignited and thereby burned; - at least one duct (18) through which at least part of the air can flow, which duct has an outflow opening (22) through which at least the part of the air flowing through the duct (18) can flow, via which at least the part of the air can be discharged from the duct (18) and fed to the combustion chamber (12); and - a closure element (30) which can be moved relative to the outflow opening (22) between at least one closed position (ST) which closes the outflow opening (22) as the first position, in which the duct (18) is fluidically separated from the combustion chamber (12), and at least one open position which opens up the outflow opening (22) as the second position, in which the duct (18) is fluidically connected to the combustion chamber (12); characterized in that at least one value is determined by means of an electronic computing device (32), which value characterizes a sum of operating states in which the internal combustion engine carries out a load jump while the closure element (30) is in the open position, wherein at least one component of the motor vehicle is operated as a function of the value.Method according to Claim 1, characterized in that a component different from the burner (12) is operated as the component.Method according to Claim 1 or 2, characterized in that the operation of the component comprises outputting at least one notification signal which can be perceived haptically and / or acoustically and / or optically by a person.Method according to any one of the preceding claims, characterized in that the operating of the component comprises moving the closure element (30) at least from one of the positions into the other position.Method according to any of the preceding claims, characterized in that the operating of the component comprises passing air through the channel (18) and the outflow opening (22) while the closure element (30) is in the open position.Method according to Claim 5, characterized in that, when the air is passed through the duct (18) and the outflow opening (22), the fuel is not passed through the duct (18).

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