Exhaust gas burner and method for heating an exhaust gas aftertreatment component

Abstract

The invention relates to an exhaust gas burner (10) comprising a housing (12); a combustion chamber (14); an air connection (16) formed on the housing (12) for connecting an air supply device of the exhaust gas burner (10); a fuel supply (18); at least one injection nozzle (22) arranged on the combustion chamber (14); at least one ignition system (20) arranged on the combustion chamber (14) for igniting a combustible fuel-air mixture; an exhaust gas line (24) connected to the combustion chamber (14), via which the exhaust gas burner (10) can be connected to an exhaust system of an internal combustion engine; a coolant inlet (28) and a coolant return (30) formed on the housing (12), via which the exhaust gas burner (10) can be connected to a coolant circuit of the internal combustion engine; cooling channels (26) formed on the housing (12), via which the heat can be dissipated from the combustion chamber (14). In an exhaust gas burner (10) in which heat dissipation can be specifically influenced, it is provided that at least one first cooling channel (32) is arranged in the region of the injection nozzle (22) and at least one second cooling channel (34) is arranged in the region of the ignition system (20).

Description

[0001] The invention relates to an exhaust gas burner with a housing and a combustion chamber, wherein an air connection for connecting an air supply device of the exhaust gas burner is formed on the housing, wherein the exhaust gas burner has a fuel supply, and wherein at least one injection nozzle and at least one ignition system for igniting a combustible fuel-air mixture are arranged on the combustion chamber and wherein an exhaust gas line is connected to the combustion chamber, via which the exhaust gas burner can be connected to an exhaust system of an internal combustion engine, wherein a coolant inlet and a coolant return are formed on the housing, via which the exhaust gas burner can be connected to a coolant circuit of the internal combustion engine, wherein cooling channels are formed on the housing, via which the heat can be dissipated from the combustion chamber.

[0002] In addition, the invention relates to a method for heating an exhaust gas aftertreatment component with an exhaust gas burner.

[0003] The continuous tightening of emissions legislation places high demands on vehicle manufacturers, which are met through appropriate measures to reduce engine-out emissions and through appropriate exhaust aftertreatment. In order to effectively convert the unavoidable raw emissions downstream of the engine, catalysts coated with precious metals are installed in the exhaust system of the combustion engine. In order for these catalysts to convert the pollutants, a minimum temperature level of the exhaust gas and the catalyst is necessary. In order to bring the catalyst up to operating temperature as quickly as possible after a cold start of the combustion engine, engine heating measures such as adjusting the ignition angle or fuel injection towards "retard" or operating the combustion engine under substoichiometric conditions with simultaneous introduction of secondary air are used.To specifically introduce even more heat energy into the exhaust system, it is possible to electrically heat the catalytic converter or install a switchable exhaust gas burner on the exhaust system to introduce hot exhaust gas into the exhaust system and heat the exhaust aftertreatment components located in the exhaust system independently of the combustion engine. This results in a very high conversion rate when the engine is started with such preconditioned catalytic converters, making compliance with increasingly stringent emissions standards possible. Emissions can be significantly reduced even during the heating phase of the catalytic converter.

[0004] Exhaust gas burners used in this process can incorporate cooling measures. Water and / or air cooling are common. For example, DE 10 2020 100 114 A1 discloses a water cooling system in which the combustion chamber of the exhaust gas burner can be cooled using a coolant from a cooling circuit. To adjust the cooling performance, a pump output can be adjusted. However, this sometimes leads to unnecessary energy consumption and possibly excessive cooling of individual components. If the injection nozzle is cooled too much, this can negatively impact the quality of spray formation and thus the mixture formation.

[0005] The invention is therefore based on the object of specifying an exhaust gas burner and a method for heating an exhaust gas aftertreatment component with an exhaust gas burner, in which a targeted influence on the heat dissipation can be exerted.

[0006] This object is achieved in the present invention by the features of patent claim 1 in that at least one first cooling channel is arranged in the region of the injection nozzle and at least one second cooling channel is arranged in the region of the ignition system.

[0007] The ignition system serves to ignite the preferably compressed fuel-air mixture in the combustion chamber. In principle, atmospheric burners without compression are also possible. However, these are rarely, if ever, used in reality. In gasoline engines, a high-voltage spark at a spark plug ignites the compressed fuel-air mixture; in diesel engines, the fuel ignites spontaneously when it is injected through a nozzle into highly compressed, hot air (self-ignition). Other prior art concepts include gasoline engines that incorporate a glow plug in the burner, and diesel engines that incorporate spark plugs in the burner, which also include the claimed ignition system.

[0008] The injector is an injection valve that injects fuel into the combustion chamber. It is preferably an electrically controlled solenoid valve.

[0009] In this way, the thermal load on the exhaust burner can be reduced, as the heat generated during fuel combustion in the exhaust burner is dissipated from the housing by the coolant in the cooling channels. This enables the use of simpler and cheaper materials, thereby reducing manufacturing costs and / or the weight of the housing. Furthermore, complex insulation of the exhaust burner to protect other components in the vicinity of the exhaust burner can be omitted, as the reduced housing temperature means less heat is transferred to other components via thermal radiation and / or conduction.

[0010] Further preferred embodiments of the invention result from the remaining features mentioned in the subclaims.

[0011] In a first embodiment of the exhaust gas burner according to the invention, the first cooling channel and the second cooling channel are connected in parallel to the coolant inlet. This allows both the injection nozzle and the ignition system to be cooled at the same flow temperature without the coolant having been preheated by another component.

[0012] In a further advantageous embodiment of the exhaust gas burner according to the invention, it is provided that a first valve is provided on the first cooling channel and a second valve is provided on the second cooling channel, so that coolant can flow through either the first cooling channel and / or the second cooling channel. This allows either the injection nozzle or the ignition system or both components to be cooled in a targeted manner. In some scenarios, for example, cooling the injection nozzle is not effective because otherwise the mixture formation can be negatively influenced. It can be provided that the valves can be controlled by means of a control unit. The valves can be designed such that they can be moved continuously from a closed to a fully open position. This allows the flow to be adjusted in a targeted manner so that the cooling capacity can be varied.

[0013] In a particularly preferred embodiment of the invention, a first fluidic connection between the first cooling channel and the second cooling channel is designed such that the first cooling channel is arranged upstream of the second cooling channel in the flow direction of the coolant, wherein at least one third valve is provided which is arranged such that the first fluidic connection between the first cooling channel and the second cooling channel is optionally open or closed. In this way, the injection nozzle and the ignition system are connected in series with regard to the coolant flow. The fluidic connection can be any suitable type of connection for conveying liquid and / or gaseous media. It is preferably a pipeline. The series connection can be optionally set or prevented by means of the third valve.In interaction, the second valve can be closed when the third valve is open, so that instead of a parallel flow and corresponding parallel cooling of the injector and the ignition system, the coolant is switched to an exclusively serial flow, first to the injector and then to the ignition system. The third valve can be an adjustable valve. It is also conceivable to provide a check valve that only allows one flow direction, from the first cooling channel to the second cooling channel.

[0014] Additionally or alternatively, in a preferred embodiment of the exhaust gas burner according to the invention, a fluidic connection between the first cooling channel and the second cooling channel is designed such that the second cooling channel is arranged upstream of the first cooling channel in the flow direction of the coolant, wherein at least one fourth valve is provided which is arranged such that the second fluidic connection between the second cooling channel and the first cooling channel is optionally open or closed. Analogous to the above embodiment, this wiring makes it possible for the ignition system to be cooled first and then the injection nozzle. The coolant is thus heated up first, so that a lower cooling capacity is available for cooling the injection nozzle. The fourth valve can also be adjustable or, for example, designed as a check valve.

[0015] By selecting the appropriate valve positions, the required coolant quantity can be optimized.

[0016] To further increase the efficiency of coolant use, a further embodiment of the invention provides temperature monitoring at the injection nozzle and / or temperature monitoring at the ignition system. The temperature monitoring, for example in the form of one or more sensors and / or a computer model that can estimate the temperature, provides information about the heating of the components and, accordingly, the cooling capacity required to cool these components to the required level. The temperature monitoring can, for example, be connected to the control unit that can control the valve position. In this way, the optimal flow setting for the coolant can be found depending on the temperature of the individual components.

[0017] The aforementioned object is also achieved by a method for heating an exhaust gas aftertreatment component using an exhaust gas burner according to the invention. It is provided that the exhaust gas aftertreatment component is heated by the hot burner exhaust gas of the exhaust gas burner before or after the combustion engine has started, with the heat from the injection nozzle and / or the heat from the ignition system being dissipated to the coolant circuit of the combustion engine via a liquid coolant. The above statements regarding the exhaust gas burner according to the invention also apply analogously to the method according to the invention.Such a process makes it possible to heat both the exhaust aftertreatment component, in particular a catalyst, and the coolant of the combustion engine, thereby reducing the raw emissions of the combustion engine and at the same time enabling efficient conversion of pollutants in the exhaust stream of the combustion engine as soon as the combustion engine is started.

[0018] The exhaust gas aftertreatment component is preferably a catalytic converter. The catalytic converter is preferably designed as a three-way catalytic converter or a four-way catalytic converter. A three-way catalytic converter can reduce both emissions of unburned hydrocarbons and carbon monoxide, as well as nitrogen oxide emissions. A four-way catalytic converter can also reduce particulate emissions from the combustion engine. In a four-way catalytic converter, the exhaust gas burner can also be used to initiate regeneration of the four-way catalytic converter independently of the operating point of the combustion engine and to heat the four-way catalytic converter to a temperature sufficient to oxidize the soot particles retained in the four-way catalytic converter.

[0019] Alternatively, it is advantageously provided that the catalyst is designed as an oxidation catalyst, a NOx storage catalyst, or an SCR catalyst. These catalysts can convert at least a portion of the limited exhaust gas components into unlimited exhaust gas components. These catalysts also require a minimum temperature necessary for conversion, which can be achieved by introducing the hot burner exhaust gases from the exhaust gas burner even before the combustion engine starts.

[0020] In a first embodiment of the method according to the invention, a coolant pump of the coolant circuit of the internal combustion engine conveys the coolant through the housing of the exhaust burner when the exhaust burner is activated. By connecting the housing to the coolant circuit of the internal combustion engine, the coolant pump of the internal combustion engine can be used to convey the coolant through the housing of the exhaust burner and to dissipate the heat from the combustion chamber of the exhaust burner.

[0021] In a particularly preferred embodiment of the method according to the invention, valves of the exhaust gas burner are controlled by a control unit, with the valves being controlled as a function of the temperature of the injection nozzle and / or the temperature of the ignition system. In this way, the optimal flow setting for the coolant can be found depending on the temperature of the individual components.

[0022] In a further embodiment of the method according to the invention, the temperature is determined by means of a temperature monitor, wherein the temperature monitor evaluates information from temperature sensors and / or determines a temperature using a computational model. The temperature can therefore be measured or estimated or determined mathematically. Of course, both variants can also be used, whereby a comparison of the data can lead to a higher accuracy of the determination.

[0023] The various embodiments of the invention mentioned in this application can be advantageously combined with one another, unless stated otherwise in the individual case.

[0024] The invention is explained below in exemplary embodiments with reference to the accompanying drawings. They show: Fig. 1 an embodiment of an exhaust gas burner according to the invention for heating an exhaust gas aftertreatment component of an internal combustion engine, Fig. 2 a schematic representation of a connection of coolant channels of an exhaust gas burner in a parallel connection, Fig. 3 a schematic representation of a circuit of coolant channels of an exhaust gas burner in a serial circuit and Fig. 4 a schematic representation of a connection of coolant channels of an exhaust gas burner with several connection options.

[0025] Fig. 1 shows an exemplary embodiment of an exhaust gas burner 10 according to the invention for heating an exhaust gas aftertreatment component of an internal combustion engine. The exhaust gas burner 10 has a metallic housing 12, preferably an aluminum housing, in which a combustion chamber 14 is formed. The combustion chamber 14 has an air connection 16, via which fresh air can be supplied to the combustion chamber 14. The combustion chamber 14 further has a fuel supply 18, via which a liquid or gaseous fuel is supplied to the combustion chamber 14, which can be exothermically converted by means of the fresh air supplied via the air connection 16. For this purpose, an ignition system 20 and an injection nozzle 22 are arranged on the combustion chamber 14 in order to inject and ignite a combustible fuel-air mixture.Furthermore, the combustion chamber 14 is connected to an exhaust pipe 24, which can be connected to an exhaust duct of an internal combustion engine, which is not shown here.

[0026] A cooling channel 26 is formed in the housing 12, which connects a coolant inlet 28 to a coolant return 30. The cooling channel 26 extends through the housing 12 of the exhaust gas burner 10 to enable the most efficient heat dissipation possible and prevent thermal damage to the housing 12. The coolant inlet 28 and the coolant return 30 are connectable to a coolant circuit of an internal combustion engine.

[0027] In the area of ​​the combustion chamber, the cooling channel divides into a first cooling channel 32 and a second cooling channel 34, with the first cooling channel 32 located in the area of ​​the injection nozzle 22. The second cooling channel 34 is located in the area of ​​the ignition system 20. In the direction of the coolant return line 32, the first cooling channel 32 and the second cooling channel 34 converge again to form a cooling channel 26. Consequently, coolant can flow through the first cooling channel 32 and the second cooling channel 34 in parallel.

[0028] Fig. 2 shows schematically an embodiment of a circuit according to the Fig. 1. In order to adjust the flow rate of the coolant in the first cooling channel 32 and the second cooling channel 34, a first valve 36 and a second valve 38 are provided. In this way, coolant can optionally flow through the first cooling channel 32 and / or the second cooling channel 34. Thus, either the injection nozzle 22 or the ignition system 20 or both components can be specifically cooled. In some scenarios, for example, cooling the injection nozzle 22 is not expedient, as otherwise the mixture formation can be negatively influenced. In this exemplary embodiment, the first valve 36 and the second valve 38 are controlled by means of a control unit 40. The valves 36, 38 can be moved continuously from a closed to a fully open position. The flow rate can thus be specifically adjusted so that the cooling performance can be varied.

[0029] Fig. 3 shows an additional connection of the first cooling channel 32 to the second cooling channel 34. In this exemplary embodiment, a first fluidic connection 42 between the first cooling channel 32 and the second cooling channel 34 is designed such that the first cooling channel 32 is arranged upstream of the second cooling channel 34 in the flow direction of the coolant. For this purpose, a third valve 44 is provided, which is arranged such that the first fluidic connection 42 between the first cooling channel 32 and the second cooling channel 34 is optionally open or closed. In this way, the injection nozzle 22 and the ignition system 20 are connected in series with respect to the coolant flow. The first fluidic connection 42 is a pipeline. The series connection can be optionally set or prevented by means of the third valve 44.

[0030] Fig. 4 shows, in addition to the Fig.3, a second fluidic connection 46, in the form of a pipe, is formed between the first cooling channel 32 and the second cooling channel 34 such that the second cooling channel 34 is arranged upstream of the first cooling channel 32 in the flow direction of the coolant. A fourth valve 48 is provided, which is arranged such that the second fluidic connection 46 between the second cooling channel 34 and the first cooling channel 32 is optionally open or closed. Analogous to the above embodiment, this wiring makes it possible for the ignition system 20 and then the injection nozzle 22 to be cooled. The coolant is thus heated up first, so that a lower cooling capacity is available for cooling the injection nozzle 22. The required coolant quantity can be optimized by selecting the appropriate valve positions.

[0031] To further increase the efficiency of coolant use, a temperature monitor 50 is provided at the injection nozzle 22 and at the ignition system 20. The temperature monitor 50, in the form of several sensors, provides information about the heating of the components and, accordingly, the cooling capacity required to cool these components to the required level. The temperature monitor is connected to the control unit 40, which controls the valve position. In this way, the optimal flow setting for the coolant can be found depending on the temperature of the individual components. List of reference symbols 10 exhaust gas burners 12 housings 14 Combustion chamber 16 Air connection 18 Fuel supply 20 Ignition system 22 Injector nozzle 24 exhaust pipe 26 Cooling channel 28 Coolant inlet 30 Coolant return 32 first cooling channel 34 second cooling channel 36 first valve 38 second valve 40 Control unit 42 first fluidic connection 44 third valve 46 second fluidic connection 48 fourth valve 50 Temperature monitoring QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2020 100 114 A1

[0004]

Claims

[1] Exhaust gas burner (10) comprising a housing (12); a combustion chamber (14); an air connection (16) formed on the housing (12) for connecting an air supply device of the exhaust gas burner (10); a fuel supply (18); at least one injection nozzle (22) arranged on the combustion chamber (14); at least one ignition system (20) arranged on the combustion chamber (14) for igniting a combustible fuel-air mixture; an exhaust gas line (24) connected to the combustion chamber (14), via which the exhaust gas burner (10) can be connected to an exhaust system of an internal combustion engine; a coolant inlet (28) and a coolant return (30) formed on the housing (12), via which the exhaust gas burner (10) can be connected to a coolant circuit of the internal combustion engine; cooling channels (26) formed on the housing (12) through which the heat can be dissipated from the combustion chamber (14), characterized by that at least one first cooling channel (32) is arranged in the region of the injection nozzle (22) and at least one second cooling channel (34) is arranged in the region of the ignition system (20). [2] Exhaust gas burner (10) according to claim 1, characterized by that the first cooling channel (32) and the second cooling channel (34) are connected in parallel to the coolant inlet (28). [3] Exhaust gas burner (10) according to claim 2, characterized by that a first valve (36) is provided on the first cooling channel (32) and a second valve (38) is provided on the second cooling channel (34), so that coolant can flow through either the first cooling channel (32) and / or the second cooling channel (34). [4] Exhaust gas burner (10) according to claim 3, characterized bythat a first fluidic connection (42) between the first cooling channel (32) and the second cooling channel (34) is designed such that the first cooling channel (32) is arranged upstream of the second cooling channel (34) in the flow direction of the coolant, wherein at least one third valve (44) is provided which is arranged such that the first fluidic connection (42) between the first cooling channel (32) and the second cooling channel (34) is selectively open or closed. [5] Exhaust gas burner (10) according to claim 3 or 4, characterized bythat a fluidic connection (46) between the first cooling channel (32) and the second cooling channel (34) is designed such that the second cooling channel (34) is arranged upstream of the first cooling channel (32) in the flow direction of the coolant, wherein at least one fourth valve (48) is provided which is arranged such that the second fluidic connection (46) between the second cooling channel (34) and the first cooling channel (32) is selectively open or closed. [6] Exhaust gas burner (10) according to one of claims 1 to 4, characterized by that a temperature monitor (50) is provided on the injection nozzle (22) and / or a temperature monitor (50) on the ignition system (20). [7] Method for heating an exhaust gas aftertreatment component with an exhaust gas burner (10) according to one of claims 1 to 6, characterized bythat the exhaust gas aftertreatment component is heated before a start of the internal combustion engine or from a start of the internal combustion engine by the hot burner exhaust gas of the exhaust gas burner (10), wherein the heat of the injection nozzle (22) and / or the heat of the ignition system (20) is dissipated to the coolant circuit of the internal combustion engine via a liquid coolant. [8] Method according to claim 7, characterized by that a coolant pump of the coolant circuit of the internal combustion engine conveys the coolant through the housing (12) of the exhaust gas burner (10) when the exhaust gas burner (10) is activated. [9] Method according to claim 7 or 8, characterized by that valves (36, 38, 44, 48) of the exhaust gas burner (10) are controlled by a control unit (40), wherein the valves (36, 38, 44, 48) are controlled as a function of the temperature of the injection nozzle (22) and / or the temperature of the ignition system (20). [10] Method according to claim 9, characterized bythat the temperature is determined by means of a temperature monitoring device (50), wherein the temperature monitoring device (50) evaluates information from temperature sensors and / or determines a temperature by means of a calculation model.

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