Method for operating an exhaust gas burner and exhaust gas burner

Abstract

The invention relates to a method for operating an exhaust gas burner (50) on an exhaust system (20) of an internal combustion engine (10), wherein an inlet point (80) for a burner exhaust gas is arranged downstream of an outlet (18) of the internal combustion engine (10) and upstream of at least one exhaust gas aftertreatment component (28, 30, 32) in the exhaust system (20). A fuel injector (78) for injecting a fuel into the combustion chamber (52) and an ignition element (56) for igniting the fuel injected into the combustion chamber (52) are arranged on a combustion chamber (52) of the exhaust gas burner (50). The method comprises the following steps: - heating a combustion chamber (52) of the exhaust gas burner in a preheating phase by a heating element (56), wherein - in a preheating phase of the combustion chamber (52), a pilot injection quantity is injected into the combustion chamber (52), and wherein - after the preheating phase has ended, a regular supply of fuel and air is carried out into the combustion chamber (52) of the exhaust gas burner (50). The invention further relates to a control device for controlling an exhaust gas burner (50), a computer program (96) and an exhaust gas burner (50) for carrying out such a method.

Description

[0001] The invention relates to a method for operating an exhaust gas burner on an exhaust system of an internal combustion engine and to an exhaust gas burner for carrying out such a method according to the preamble of the independent patent claims.

[0002] Current and increasingly stringent emissions legislation places high demands on raw emissions and exhaust aftertreatment in internal combustion engines. The demands for further reduced fuel consumption and the further tightening of emissions standards regarding permissible nitrogen oxide emissions pose a challenge for engine developers. In gasoline engines, exhaust gas purification is achieved in the usual way via a three-way catalytic converter, as well as additional catalysts upstream and downstream of the three-way catalytic converter and a particulate filter. Diesel engines currently use exhaust aftertreatment systems that include an oxidation catalyst, a catalyst for the selective catalytic reduction of nitrogen oxides (SCR catalyst), a particulate filter for the separation of soot particles, and possibly additional catalysts. Ammonia is the preferred reducing agent.Because handling pure ammonia is complex, vehicles typically use a synthetic, aqueous urea solution, which is mixed with the hot exhaust stream in a mixing device upstream of the SCR catalyst. This mixing heats the aqueous urea solution, releasing ammonia into the exhaust duct. A commercially available aqueous urea solution generally consists of 32.5% urea and 67.5% water.

[0003] In view of further tightening of emissions standards, for example, with the introduction of the EU7 standard, it is necessary to significantly reduce cold-start emissions, which account for a large portion of total emissions. During cold-start operation, i.e., immediately after starting the combustion engine, the exhaust aftertreatment components are generally not sufficiently warmed up to enable conversion of the raw emissions produced during fuel combustion. This leads to increased emissions, particularly during the cold-start phase, which, even with complete conversion of the emissions after the cold-start phase, means that the limit values ​​are no longer met.

[0004] DE 10 2020 215 289 A1 discloses a method for operating an exhaust gas burner in an exhaust aftertreatment system of an internal combustion engine of a motor vehicle. The method comprises operating an ignition device of the exhaust gas burner, detecting at least one operating parameter of the ignition device, determining an ignition state in the exhaust gas burner based on the detected operating parameter, and performing a measure depending on the ignition state.

[0005] DE 10 2021 203 083 A1 describes a method for operating an exhaust gas burner downstream of an internal combustion engine and upstream of an exhaust gas catalytic converter, comprising activating an ignition device of the exhaust gas burner during a predeterminable preheating phase without supplying fuel to the exhaust gas burner during the preheating phase. After the preheating phase has elapsed, fuel is supplied to the exhaust gas burner and the supplied fuel is combusted in the exhaust gas burner. Furthermore, a computing unit and a computer program product for implementing such a method are proposed.

[0006] DE 10 2022 206 800 A1 discloses a method for operating an exhaust gas burner with a secondary air system, which is arranged in an exhaust system of an internal combustion engine. The method comprises the following steps: - Activation of an ignition device, depending on a release condition, whereby the ignition device is heated to a predeterminable target temperature, - metering fuel at a first time into a combustion chamber of the exhaust gas burner with a predeterminable first injection frequency by means of an injection valve, wherein no air is actively added to the combustion chamber of the exhaust gas burner, - Setting a first target air mass flow by means of a secondary air system at a further second point in time, wherein the air mass flow is increased.

[0007] Furthermore, US 2002 / 0000087 A1 discloses a method for monitoring a heating element in the exhaust system of an internal combustion engine, which serves to heat an exhaust aftertreatment component to its operating temperature.

[0008] The invention is based on the object of being able to carry out a diagnosis of the functionality of the exhaust gas burner in order to reduce the emissions of an internal combustion engine, particularly during a cold start phase.

[0009] The object is achieved by a method for operating an exhaust gas burner on an exhaust system of an internal combustion engine, wherein an inlet point of a burner exhaust gas is arranged downstream of an outlet of the internal combustion engine and upstream of at least one exhaust gas aftertreatment component in the exhaust system, wherein a fuel injector for injecting a fuel into the combustion chamber and an ignition element for igniting the fuel injected into the combustion chamber are arranged on a combustion chamber of the exhaust gas burner, comprising the following steps: - Controlling the fuel injector to inject a pilot amount of fuel into the combustion chamber of the exhaust gas burner, - Diagnosis of the fuel injector, whether the control has led to the opening of a fuel injection valve of the fuel injector and the metering of fuel into the combustion chamber of the exhaust gas burner, - Controlling the ignition element to ignite the pilot quantity of fuel injected into the combustion chamber, - Diagnosis of the ignition element, whether the control of the ignition element leads to the ignition conditions being reached in the combustion chamber of the exhaust gas burner.

[0010] In this context, an exhaust gas burner is a burner that combusts fuel, particularly liquid fuel, through ignition and produces a hot burner exhaust gas that can be used to heat an exhaust component in the exhaust system of the internal combustion engine. An ignition element in this context is a device that ignites a fuel-air mixture in the combustion chamber of the exhaust gas burner, particularly a glow plug or a spark plug.

[0011] The method according to the invention enables on-board diagnosis of the function of the exhaust gas burner, whereby both the function of the fuel injector and the function of the ignition element in the combustion chamber are checked. In particular, it can be detected whether actuation of the fuel injector has actually led to fuel injection or whether a malfunction has occurred due to the fuel injection valve sticking. Furthermore, it is detected whether the ignition element is functional or whether the ignition element is permanently damaged so that it is no longer functional for igniting the injected fuel. The injected pilot quantity ensures that the fuel is evenly distributed in the combustion chamber and thus improves mixture formation in order to produce an ignitable fuel-air mixture at least in the area of ​​the ignition element.Furthermore, the injected pilot quantity is so small that even in the event of a misfire, no significant increase in emissions of unburned hydrocarbons is to be expected and the limits of the exhaust gas legislation are complied with.

[0012] The additional features listed in the dependent claims enable advantageous further developments and improvements of the method for operating an exhaust gas burner described in the independent claim.

[0013] In an advantageous embodiment of the method, the diagnosis of the function of the fuel injector is carried out by a current measurement and / or a voltage measurement of a control current and / or a control voltage of the fuel injector. Opening of the fuel injection valve can be reliably detected with a continuous current and / or voltage measurement due to the induction by the moving valve needle of the fuel injection valve. The function of the fuel injector can therefore be deduced from the course of the current and / or voltage measurement. In the event of a malfunction, measures can be initiated to prevent an unacceptable increase in emissions. These measures can include, among other things, a renewed attempt to start the exhaust gas burner, a restriction of the torque and / or power of the combustion engine, or an abort of the starting process of the combustion engine.Furthermore, information can be given to the driver that there is a fault in the exhaust gas burner or the exhaust gas aftertreatment system and / or the driver can be asked to visit a workshop to have the exhaust gas burner checked and, if necessary, replaced.

[0014] In a further advantageous embodiment of the method, it is provided that in the event of a negative diagnosis of the function of the fuel injector, i.e. in the event of an activation process which does not result in the fuel injection valve opening and fuel injection by the fuel injector, at least one further activation of the fuel injector and a further diagnosis of the function of the fuel injector take place upon renewed activation. This makes it possible to start the exhaust gas burner if the further functional test was successful and led to the injection of a pilot quantity into the combustion chamber of the exhaust gas burner. In particular, cold ambient temperatures and / or poor fuel quality can lead to the fuel injection valve of the exhaust gas burner "sticking" and, despite the fuel injector being activated, no fuel being injected into the combustion chamber of the exhaust gas burner.By re-activating the fuel injector, such sticking can be resolved if necessary, so that from the time the fuel injector opens for the first time, proper injection can be assumed in the subsequent operation. If the second or further activation does not result in the fuel injector opening, measures must be taken to prevent an unacceptable increase in emissions. These measures can, in particular, include limiting the torque and / or power of the combustion engine during the start-up phase. If the fuel injector is heated up by the coolant circuit of the combustion engine at a later point in time, a new attempt to start the exhaust gas burner can be made from this point onwards using a proposed method.

[0015] It is particularly preferred if the second or subsequent actuation of the fuel injector occurs with a longer actuation duration. This increases the opening forces on the valve needle of the fuel injector, causing the fuel injector to open. If actuation with an extended actuation duration does not result in proper function of the fuel injector and injection of a pilot quantity, measures must be taken to prevent an unacceptable increase in emissions. These measures may, in particular, include limiting the torque and / or power of the combustion engine during the start-up phase.

[0016] In an advantageous embodiment of the method, the first activation of the fuel injector and the second activation of the fuel injector, as well as any further activations of the fuel injector, occur within one second. Similar to the preheating of the glow plugs of a diesel engine during a start-up process, such a delay is generally considered acceptable by the driver, so that the functional test of the exhaust gas burner can be carried out essentially without any restrictions for the driver.

[0017] In a preferred embodiment of the method, the functionality of the ignition element is diagnosed by evaluating the current characteristic and / or the voltage characteristic of the ignition element. This makes it possible to detect a blown ignition element, in particular a blown glow plug or a defective spark plug, since such a defect leads to a significant change in the current and / or voltage characteristic. Furthermore, a change in the current characteristic and / or the voltage characteristic due to aging of the ignition element can be detected and at least partially compensated for by appropriately adapting the control. This ensures that the fuel injected into the combustion chamber of the exhaust gas burner is ignited reliably.Under certain circumstances, a replacement recommendation for the ignition element, in particular the glow plug or the spark plug, can be made or stored in a control unit based on the determined aging state of the ignition element.

[0018] In a preferred embodiment of the method, the ignition element is a glow plug, and the diagnosis is performed by detecting the temperature in the combustion chamber or detecting the temperature of a glow plug element. A corresponding temperature increase resulting from the activation of the glow plug can indicate proper functioning of the glow plug. Thus, proper functioning of the ignition element, which is necessary for starting the exhaust gas burner, can be verified in a simple and cost-effective manner.

[0019] Alternatively or additionally, the ignition element may comprise a spark plug, with the ignition element being diagnosed by measuring the current of an ignition coil of the ignition element. This allows the spark plug's function to be checked to ensure reliable ignition of the injected fuel when the exhaust gas burner starts.

[0020] Preferably, the diagnosis of the ignition element, especially when using a glow plug as the ignition element, is carried out after the diagnosis of the fuel injector, since otherwise a hot glow plug can lead to uncontrolled ignition of the injected fuel during the function test of the fuel injector.

[0021] In a preferred embodiment of the invention, the pilot injection quantity is a fuel quantity of 0.5 mg to 5 mg, preferably a fuel quantity of 1 mg to 3 mg, of fuel. Such a small amount of fuel can deposit in the combustion chamber of the exhaust gas burner without causing a significant increase in the emissions of unburned hydrocarbons. Rather, the metering of such a small amount can lead to the fuel being evenly distributed in the combustion chamber of the exhaust gas burner and forming an ignitable fuel-air mixture, thereby facilitating starting of the exhaust gas burner.

[0022] In a further preferred embodiment of the invention, the pilot injection quantity is introduced into the combustion chamber of the exhaust gas burner in exactly one injection event. By injecting fuel once during the preheating phase, the specified fuel quantity can be easily introduced into the combustion chamber of the exhaust gas burner. Furthermore, a functional check of the fuel injector can ensure that the specified quantity of fuel was actually injected into the combustion chamber of the exhaust gas burner during the preheating phase.

[0023] In an advantageous embodiment of the method, after a preheating phase, several fuel injections are performed into the combustion chamber of the exhaust gas burner, with an injection characteristic being changed until the combustion chamber of the exhaust gas burner reaches a threshold temperature. This allows the exhaust gas burner to be started easily after the preheating phase, with further heating up to the threshold temperature being controlled by a special injection application for the start-up phase. This enables a particularly low-emission start-up of the exhaust gas burner.

[0024] In a further advantageous embodiment of the method, the combustion chamber of the exhaust gas burner is heated by a glow plug arranged in the combustion chamber. A glow plug can be used to simply and cost-effectively introduce a corresponding amount of heat into the combustion chamber during the preheating phase of the exhaust gas burner in order to ensure reliable ignition of the fuel injected into the combustion chamber. This can facilitate the start of the exhaust gas burner, thus reliably preventing malfunctions during the start-up phase of the exhaust gas burner, which would otherwise lead to increased emissions. The longer the glow plug burns, the more heat is introduced into the combustion chamber of the exhaust gas burner.

[0025] Alternatively or additionally, it is advantageously provided that a spark plug is arranged in the combustion chamber of the exhaust gas burner, wherein an ignitable fuel-air mixture is ignited in the combustion chamber by the spark plug. In the case of a spark plug, the combustion duration can be varied by selecting a suitable ignition coil. Multiple ignitions can also be used to extend the preheating phase. Depending on the fuel used, it can be helpful if a spark plug is arranged in the combustion chamber of the exhaust gas burner to ensure reliable ignition of a fuel-air mixture in the combustion chamber.

[0026] In a preferred embodiment of the method, the preheating phase of the combustion chamber of the exhaust gas burner lasts a maximum of 10 seconds, preferably a maximum of 5 seconds, particularly preferably a maximum of 2 seconds, and ideally a maximum of 1 second. A short preheating phase of the exhaust gas burner ensures that the exhaust gas burner is ready for operation with a slight delay after the internal combustion engine has started, thus enabling efficient heating of the exhaust gas aftertreatment components of the internal combustion engine. This shortens the period from the start of the internal combustion engine to the point at which the pollutants contained in the exhaust gas stream of the internal combustion engine can be efficiently converted, thereby reducing cold-start emissions from the internal combustion engine.

[0027] According to an advantageous embodiment of the invention, the method comprises determining a start and / or a duration of the preheating phase as a function of input signals, which in particular comprise one or more from the group consisting of a temperature, a locking state of a vehicle door, a seat occupancy state, a seat belt buckle state, a state of charge of a battery of a hybrid vehicle, and a start request of the internal combustion engine. This allows the preheating phase to be planned in a targeted manner when a start of the internal combustion engine becomes likely, which can be determined using the aforementioned input signals, or the preheating phase can be adapted to an estimated heating requirement, in particular as a function of an outside temperature. This enables precise control with minimal energy losses and maximum efficiency.

[0028] In an advantageous embodiment of the method, the output of the exhaust gas burner is increased to a nominal output of the exhaust gas burner within less than five seconds, preferably within less than three seconds, particularly preferably within less than 1.5 seconds after the end of the preheating phase. This enables rapid heating of the exhaust gas aftertreatment components arranged downstream of the burner, in particular a three-way catalyst, an oxidation catalyst, an SCR catalyst, or a NOx storage catalyst.

[0029] A further aspect of the invention relates to a control unit for controlling an exhaust gas burner in an exhaust system of an internal combustion engine, wherein the control unit is configured to execute all method steps of a method for controlling an exhaust gas burner described in the preceding paragraphs. Such a control unit can, in particular, be a control unit for controlling the internal combustion engine, wherein the control of the exhaust gas burner can be applied as an additional function in the control unit, thus eliminating the need for an additional control unit. This enables a particularly cost-effective implementation of such a method.

[0030] Alternatively, the exhaust gas burner can have its own control unit, whereby the control of the exhaust gas burner is comparatively simple compared to the control of the combustion engine, so that a simple, cost-effective control unit with a smaller range of functions can be used to control the exhaust gas burner.

[0031] A further aspect of the invention relates to a computer program that causes a control unit for controlling an exhaust gas burner to perform the method steps of a method according to the invention when executed by a computing unit of the control unit. Such a computer program can enable the execution of a method described in the preceding paragraphs in a simple and advantageous manner if it is applied as computer program code in a control unit operatively connected to the exhaust gas burner.

[0032] A further aspect of the invention relates to a machine-readable storage medium having a computer program described in the preceding paragraph stored thereon. Such a storage medium can provide a computer program code for implementing a method according to the invention for controlling an exhaust gas burner. In particular, such a storage medium can be a memory unit of a control device for controlling the exhaust gas burner. Alternatively, such a storage medium can be inserted into a control unit in order to execute, upon activation, a method for controlling an exhaust gas burner described in the preceding paragraphs.

[0033] A further aspect of the invention relates to an exhaust gas burner with a combustion chamber for combusting a fuel, in which the combustion chamber is connected to an air supply system and a fuel supply system. An ignition element for igniting a fuel-air mixture is arranged in the combustion chamber. The exhaust gas burner is operatively connected to a control unit described in the preceding paragraphs in order to carry out a method for controlling an exhaust gas burner described in the preceding paragraphs. Such an exhaust gas burner makes it possible to reduce emissions from the internal combustion engine because the exhaust gas aftertreatment components can be quickly heated to their operating temperature during a cold start of the internal combustion engine and / or after cooling down in order to enable efficient conversion of the pollutants in the exhaust stream of the internal combustion engine.In this case, an exhaust gas burner according to the invention additionally prevents an unacceptable increase in emissions when the exhaust gas burner is activated.

[0034] The various embodiments of the invention mentioned in this application can be advantageously combined with one another, unless stated otherwise in the individual case.

[0035] The invention is explained below in exemplary embodiments with reference to the accompanying drawings. They show: Fig. 1 shows a preferred embodiment of an internal combustion engine with an exhaust system on which an exhaust gas burner according to the invention is arranged for heating at least one exhaust gas aftertreatment component, Fig. 2 shows a further preferred embodiment of an internal combustion engine with an exhaust system on which an exhaust gas burner according to the invention is arranged for heating at least one exhaust gas aftertreatment component of the internal combustion engine, Fig. 3 an exhaust gas burner according to the invention for the exhaust system of an internal combustion engine, Fig. 4 a diagram for the inventive control of an exhaust gas burner on an exhaust system of an internal combustion engine.

[0036] Fig. 1 shows a first exemplary embodiment of an internal combustion engine 10 with at least one combustion chamber 12, wherein a fuel injector 14 and a spark plug 16 for igniting an ignitable fuel-air mixture are arranged at the combustion chamber 12. The internal combustion engine 10 is designed as a direct-injection gasoline engine. The internal combustion engine 10 is connected by its outlet 18 to an exhaust system 20, which has an exhaust duct 26. In the exhaust system 20, in the flow direction of an exhaust gas flow through the exhaust system 20, a turbine 24 of an exhaust gas turbocharger 22 and downstream of the turbine 24 a first exhaust gas aftertreatment component 28, further downstream a second exhaust gas aftertreatment component 30 and even further downstream a third exhaust gas aftertreatment component 32 are arranged. In the Fig. 1, the first exhaust aftertreatment component 28 is a first three-way catalyst 34, the second exhaust aftertreatment component 30 is a second three-way catalyst 36, and the third exhaust aftertreatment component 32 is a particulate filter 38.

[0037] Furthermore, an exhaust gas burner 50 is arranged on the exhaust system 20. The exhaust gas burner 50 comprises a combustion chamber 52, an air supply system 60, and a fuel supply system 70. The air supply system 60 comprises an air compressor 62 for supplying fresh air to the combustion chamber 52 of the exhaust gas burner 50 and an air valve 64 for controlling the amount of air supplied to the combustion chamber 52 of the exhaust gas burner 50. The air supply system 60 further comprises an air line 66, which connects the air compressor 62 to the combustion chamber 52 of the exhaust gas burner 50. Furthermore, an air mass meter 68, in particular a hot-film air mass meter, is arranged in the air supply system 60 to measure the amount of air supplied to the combustion chamber 52. The fuel supply system 70 of the exhaust gas burner 50 comprises a fuel tank 72, a fuel pump 74 and a fuel injector 78, which enables fuel to be metered into the combustion chamber 52 of the exhaust gas burner.The fuel tank 72 is connected to the fuel injector 78 via a fuel line 76. The combustion chamber 52 of the exhaust gas burner 50 is connected via an exhaust line to an inlet point 80 on the exhaust duct 26 of the exhaust system 20 in order to introduce a hot burner exhaust gas from the exhaust gas burner 50 upstream of at least one exhaust gas aftertreatment component 28, 30, 32 into the exhaust duct 26 and to heat the exhaust gas aftertreatment component(s) 28, 30, 32 arranged downstream of the inlet point 80 by the hot burner exhaust gas from the exhaust gas burner 50.

[0038] An ignition element 56 is provided in the combustion chamber 52 to ignite fuel injected into the combustion chamber 52 of the exhaust gas burner 50 by means of the fuel injector 78. Furthermore, the ignition element 56 can serve to heat the combustion chamber 52 of the exhaust gas burner 50, in particular before the start of fuel injection into the combustion chamber 52 of the exhaust gas burner 50 and / or before the start of the internal combustion engine 10. The ignition element 56 can be designed, in particular, as a glow plug 58 or as a spark plug 54. The exhaust gas burner 50 is configured to introduce a hot burner exhaust gas from the exhaust gas burner 50 at the inlet point 80 into the exhaust gas duct 26 of the exhaust system 20 in order to heat at least one exhaust gas aftertreatment component 28, 30, 32 arranged downstream of the inlet point 80 to its operating temperature, in particular to a light-off temperature of a catalyst.

[0039] However, the invention is not limited to the Fig. 1, but can be implemented on any exhaust system 20 on which at least one exhaust gas aftertreatment component 28, 30, 32 is arranged downstream of the inlet point 80 of the exhaust gas burner 50.

[0040] The internal combustion engine 10 and the exhaust gas burner 50 are connected to a control unit 90, which includes a memory unit 94 and a computing unit 92. A computer program 96 is stored in the memory unit 94, which controls a method for operating the exhaust gas burner 50 when the computer program 96 is executed by the computing unit 92 of the control unit 90.

[0041] In Fig. 2 shows an alternative embodiment of an internal combustion engine 10 with an exhaust system 20 and an exhaust gas burner 50 according to the invention. The internal combustion engine 10 is designed as a direct-injection diesel engine and has a plurality of combustion chambers 12. A fuel injector 14 for injecting a fuel into the respective combustion chamber 12 is arranged at each of the combustion chambers 12. The internal combustion engine 10 has an inlet via which the combustion chamber 12 is connected to an intake tract of the internal combustion engine 10 and through which fresh air can flow into the combustion chambers 12 of the internal combustion engine. The internal combustion engine 10 further has an outlet 18, which is connected to an exhaust system 20 of the internal combustion engine 10.

[0042] The exhaust system 20 comprises an exhaust duct 26, in which a turbine 24 of an exhaust gas turbocharger 22 is arranged in the flow direction of an exhaust gas from the internal combustion engine 10 through the exhaust duct 26. This turbine drives a compressor (not shown) arranged in the intake tract of the internal combustion engine 10 via a shaft. The exhaust gas turbocharger 22 is preferably designed as an exhaust gas turbocharger 22 with variable turbine geometry. For this purpose, adjustable guide vanes are arranged upstream of a turbine wheel of the turbine 24, via which guide vanes the flow of the exhaust gas onto the blades of the turbine 24 can be varied. Downstream of the turbine 24, a plurality of exhaust gas aftertreatment components 28, 30, 32 are provided in the exhaust duct 26 of the exhaust system 20. An oxidation catalyst 40 or a NOx storage catalyst 42 is arranged directly downstream of the turbine 24 as the first exhaust gas aftertreatment component 28.Downstream of the oxidation catalyst 40 or the NOx storage catalyst 42 is a particulate filter 46 with a coating for the selective catalytic reduction of nitrogen oxides (SCR coating). Further exhaust gas aftertreatment components, in particular a further SCR catalyst 44 and / or a . Fig. 2 ammonia barrier catalyst (not shown) may be arranged.

[0043] Furthermore, an exhaust gas burner 50 is arranged on the exhaust system 20. The exhaust gas burner 50 comprises a combustion chamber 52, an air supply system 60, and a fuel supply system 70. The air supply system 60 comprises an air compressor 62 for supplying fresh air to the combustion chamber 52 of the exhaust gas burner 50 and an air valve 64 for controlling the amount of air supplied to the combustion chamber 52 of the exhaust gas burner 50. The air supply system 60 further comprises an air line 66, which connects the air compressor 62 to the combustion chamber 52 of the exhaust gas burner 50. Furthermore, an air mass meter 68, in particular a hot-film air mass meter, is arranged in the air supply system 60 to measure the air mass supplied to the combustion chamber 52. The fuel supply system 70 of the exhaust gas burner 50 comprises a fuel tank 72, a fuel pump 74 and a fuel injector 78, which enables fuel to be metered into the combustion chamber 52 of the exhaust gas burner.The fuel tank 72 is connected to the fuel injector 78 via a fuel line 76.

[0044] The combustion chamber 52 of the exhaust gas burner 50 is connected via an exhaust gas line to an inlet point 80 on the exhaust gas duct 26 of the exhaust system 20 in order to introduce a hot burner exhaust gas from the exhaust gas burner 50 upstream of at least one exhaust gas aftertreatment component 28, 30, 32 into the exhaust gas duct 26 and to heat the exhaust gas aftertreatment component(s) 28, 30, 32 arranged downstream of the inlet point 80 by the hot burner exhaust gas from the exhaust gas burner 50.

[0045] An ignition element 56 is provided in the combustion chamber 52 to ignite fuel injected into the combustion chamber 52 of the exhaust gas burner 50 by means of the fuel injector 78. Furthermore, the ignition element 56 can serve to heat the combustion chamber 52 of the exhaust gas burner 50, in particular before the start of fuel injection into the combustion chamber of the exhaust gas burner 50. The ignition element 56 can be designed in particular as a glow plug 58 or as a spark plug 54. The exhaust gas burner 50 is configured to introduce a hot burner exhaust gas at the inlet point 80 into the exhaust duct 26 of the exhaust system 20 in order to heat at least one exhaust gas aftertreatment component 28, 30, 32 arranged downstream of the inlet point 80 to its operating temperature, in particular to a light-off temperature of a catalytic converter.

[0046] The internal combustion engine 10 and the exhaust gas burner 50 are connected to a control unit 90, which includes a memory unit 94 and a computing unit 92. A computer program 96 is stored in the memory unit 94, which controls a method for operating the exhaust gas burner 50 when the computer program 96 is executed by the computing unit 92 of the control unit 90.

[0047] In Fig. 3 shows a preferred embodiment of an exhaust gas burner 50 according to the invention. The exhaust gas burner 50 comprises a combustion chamber 52, an air supply system 60, and a fuel supply system 70. The air supply system 60 comprises an air compressor 62 for supplying fresh air to the combustion chamber 52 of the exhaust gas burner 50 and an air valve 64 for controlling the amount of air supplied to the combustion chamber 52 of the exhaust gas burner 50. The air supply system 60 further comprises an air line 66 connecting the air compressor 62 to the combustion chamber 52 of the exhaust gas burner 50. Furthermore, an air mass meter 68, in particular a hot-film air mass meter, is arranged in the air supply system 60 to measure the amount of air supplied to the combustion chamber 52 of the exhaust gas burner 50.Furthermore, a pressure sensor 84 and / or a temperature sensor 82 can be arranged in the air supply system to further improve the quality of the control of the amount of air supplied to the combustion chamber 52 of the exhaust gas burner 50. The fuel supply system 70 of the exhaust gas burner 50 comprises a fuel tank 72, a fuel pump 74, and a fuel injector 78, which enables fuel to be metered into the combustion chamber 52 of the exhaust gas burner. The fuel tank 72 is connected to the fuel injector 78 via a fuel line 76. Furthermore, a fuel filter, a pressure sensor 84, and / or a temperature sensor 82 can be arranged in the fuel line 76 to better control the amount of fuel supplied to the combustion chamber 52 of the exhaust gas burner and to remove impurities from the fuel through the fuel filter.

[0048] An ignition element 56 is arranged in the combustion chamber 52 for igniting the fuel injected into the combustion chamber 52 by the fuel injector 78. Furthermore, the ignition element 56 can serve to heat the combustion chamber 52, in particular before starting the exhaust gas burner 50 and / or before starting the internal combustion engine 10. The ignition element 56 can be designed, in particular, as a glow plug 58 or as a spark plug 54. The exhaust gas burner 50 is configured to introduce a hot burner exhaust gas at the inlet point 80 into the exhaust duct 26 of the exhaust system 20 in order to heat at least one of the exhaust gas aftertreatment components 28, 30, 32 to its operating temperature, in particular to a light-off temperature of a catalytic converter.

[0049] In Fig.4 shows two preferred embodiments of a method according to the invention for operating an exhaust gas burner 50 on an exhaust system 20 of an internal combustion engine 10. First, a temperature in a combustion chamber 52 of an exhaust gas burner 50 is determined. If the determined temperature T E below a threshold temperature T S, a preheating phase I is necessary to start the exhaust gas burner 50. The combustion chamber 52 is heated by an ignition element 56 arranged in the combustion chamber 52, in particular a spark plug 54 or a glow plug 58. In the preheating phase I, a first fuel quantity of 0.5 mg to 5 mg, preferably 1 mg to 3 mg, is injected into the combustion chamber 52 by the fuel injector 58 in a pilot injection. A diagnosis of the fuel injector 78 is carried out, in which the fuel injector 78 is controlled in order to inject a pilot quantity of fuel into the combustion chamber 52 of the exhaust gas burner 50 and a diagnosis is carried out as to whether the control of the fuel injector 58 has also led to an actual injection of fuel into the combustion chamber.Furthermore, in preheating phase I, a diagnosis of the ignition element 56 is carried out to ensure that, during subsequent fuel injections, ignition conditions prevail in the combustion chamber 52 of the exhaust gas burner 50 which ensure combustion of the fuel injected into the combustion chamber 52 and the associated provision of a hot burner exhaust gas for introduction into the exhaust system 20. By heating the combustion chamber 52 in the preheating phase, this fuel evaporates and forms a substantially homogeneous fuel-air mixture in the combustion chamber 52. Apart from the pilot injection, no further injection of fuel takes place into the combustion chamber 52 during preheating phase I. If the combustion chamber 52 has a threshold temperature T. sis reached, the exhaust gas burner 50 is started by igniting the fuel in the combustion chamber 52 by the ignition element 56, in particular by ignition by an ignition spark from the spark plug 54 or by ignition at the glow plug 58. Subsequently, in a heating phase III, fresh air is supplied to the combustion chamber 52 via the air supply system 60 and fuel via the fuel supply system 70, whereby the exhaust gas burner 50 can develop a high heating output for heating the exhaust gas aftertreatment components 28, 30, 32 and the exhaust gas aftertreatment components 28, 30, 32 are heated to their respective operating temperature. Between the preheating phase I and the heating phase III, a transition phase II can be provided, in which the output of the exhaust gas burner 50 is increased to its nominal output, starting from a start of the burner.A special characteristic map can be applied for the transition phase II in order to ensure the most efficient and low-emission start-up of the exhaust gas burner 50. List of reference symbols 10 Internal combustion engine 12 combustion chamber 14 Fuel injector 16 Spark plug 18 Outlet 20 Exhaust system 22 exhaust gas turbochargers 24 turbines 26 Exhaust duct 28 first exhaust aftertreatment component 30 second exhaust aftertreatment component 32 third exhaust aftertreatment component 34 first three-way catalyst 36 second three-way catalyst 38 particle filters 40 Oxidation catalyst 42 NOx storage catalyst 44 SCR catalyst 46 particulate filters with SCR coating 48 Dosing element 50 exhaust gas burners 52 Combustion chamber 54 Spark plug 56 Ignition device 58 Glow plug 60 Air supply system 62 air compressors 64 Air valve 66 Air line 68 Air mass meter 70 Fuel supply system 72 Fuel tank 74 Fuel pump 76 Fuel line 78 Fuel injector 80 discharge point 82 Temperature sensor 84 Pressure sensor 90 Control unit 92 computing unit 94 storage unit 96 computer program 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 215 289 A1

[0004] DE 10 2021 203 083 A1

[0005] DE 10 2022 206 800 A1

[0006] US 2002 / 0000087 A1

[0007]

Claims

[1] A method for operating an exhaust gas burner (50) on an exhaust system (20) of an internal combustion engine (10), wherein an inlet point (80) of a burner exhaust gas is arranged downstream of an outlet (18) of the internal combustion engine (10) and upstream of at least one exhaust gas aftertreatment component (28, 30, 32) in the exhaust system (20), wherein a fuel injector (78) for injecting a fuel into the combustion chamber (52) and an ignition element (56) for igniting the fuel injected into the combustion chamber (52) are arranged on a combustion chamber (52) of the exhaust gas burner (50), comprising the following steps: - controlling the fuel injector (78) to inject a pilot amount of fuel into the combustion chamber (52) of the exhaust gas burner (50), - Diagnosis of the fuel injector (78), whether the control has led to an opening of a fuel injection valve of the fuel injector (78) and a metering of fuel into the combustion chamber (52), - controlling the ignition element (56) to ignite the pilot quantity of fuel injected into the combustion chamber (52), - Diagnosis of the ignition element (56), whether the control of the ignition element (56) leads to the ignition conditions being reached in the combustion chamber (52) of the exhaust gas burner (50). [2] Method according to claim 1, wherein the diagnosis of the function of the fuel injector (78) is carried out by a current measurement and / or voltage measurement of a control current and / or a control voltage of the fuel injector (78). [3] Method according to claim 1 or 2, wherein in the event of a negative diagnosis of the function of the fuel injector (78), at least one further control of the fuel injector (78) and a further diagnosis of the function of the fuel injector are carried out. [4] Method according to claim 3, wherein the first actuation of the fuel injector (78) and the further actuation of the fuel injector (78) takes place within one second. [5] Method according to one of claims 1 to 4, wherein the diagnosis of the function of the ignition element (56) is carried out by evaluating the current characteristic and / or the voltage characteristic of the ignition element. [6] Method according to one of claims 1 to 5, wherein the ignition element (56) is a glow plug (58) and the diagnosis is carried out by detecting the temperature in the combustion chamber (52) or detecting the temperature of a glow pin of the glow plug (58). [7] Method according to one of claims 1 to 6, wherein the ignition element (56) comprises a spark plug (54) and the diagnosis is carried out by measuring a current of an ignition coil of the ignition element (56). [8] Control device (90) for controlling an exhaust gas burner (50) on an exhaust system (20) of an internal combustion engine (10), wherein the control device (90) is configured to carry out all method steps of a method according to one of claims 1 to 7 [9] Computer program (96) which causes a control device (90) for controlling an exhaust gas burner (50) to carry out the method steps of a method according to one of claims 1 to 7 when it is executed by a computing unit (92) of the control device (90). [10] Exhaust gas burner (50) with a combustion chamber (52) for combustion of a fuel, wherein the combustion chamber (52) is connected to an air supply system (60) and a fuel supply system (70), wherein an ignition element (54) for igniting a fuel-air mixture is arranged in the combustion chamber (52), and with a control unit (90) according to claim 8.

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