Exhaust system for an internal combustion engine of a motor vehicle as well as motor vehicle

Abstract

The invention relates to an exhaust system (10) for an internal combustion engine (12) of a motor vehicle, comprising a burner (48) that can be supplied with air and fuel, by means of which a mixture comprising air and fuel is to be burned, comprising a supply line (58) through which air can flow, via which the burner (48) can be supplied with the air flowing through the supply line (58), and comprising an air pump (56) arranged in the supply line (58), by means of which the air can be conveyed through the supply line (58) and conveyed to the burner (48) in order to supply the burner (48) with air.The system includes a branch line (68) and a combination valve (72) which can be switched between a first switching state (ST1), in which the branch line (68) is fluidically separated from the supply line (58) and the air supplied by the air pump (56) is allowed to flow through the supply line (58) and to the burner (48), and at least a second switching state (ST2).

Description

[0001] The invention relates to an exhaust system for an internal combustion engine of a motor vehicle according to the preamble of claim 1. Furthermore, the invention relates to a motor vehicle, in particular a motor car.

[0002] DE 10 2019 008 956 A1 discloses an exhaust system for an internal combustion engine, comprising a nitrogen oxide storage catalyst through which exhaust gas from the internal combustion engine flows, and a burner supplied with air and fuel, by means of which a fuel-air mixture containing the fuel and air is to be combusted. Furthermore, DE 10 2021 001 580 A1 discloses a burner for an exhaust tract through which exhaust gas from an internal combustion engine of a motor vehicle flows.

[0003] The object of the present invention is to create an exhaust system for an internal combustion engine of a motor vehicle and a motor vehicle with such an exhaust system, so that a burner of the exhaust system can be operated particularly advantageously.

[0004] This problem is solved by an exhaust system with the features of claim 1 and by a motor vehicle with the features of claim 4. Advantageous embodiments with expedient further developments of the invention are specified in the remaining claims.

[0005] A first aspect of the invention relates to an exhaust system for an internal combustion engine, also referred to as a motor or combustion engine, and designed, for example, as a reciprocating engine, i.e., a piston engine, of a motor vehicle, also simply referred to as a vehicle. This means that the motor vehicle, in its fully manufactured state, has the internal combustion engine and can be driven by means of the internal combustion engine. The internal combustion engine, in the fully manufactured state of the motor vehicle, includes the exhaust system. The exhaust system is permeable to exhaust gases from the internal combustion engine. The motor vehicle is designed, for example, as a car, in particular as a passenger car, or as a commercial vehicle.During operation of an internal combustion engine, combustion processes take place within the engine, particularly in at least one or more combustion chambers, resulting in exhaust gas, also known as engine exhaust. This exhaust gas can flow out of the respective combustion chamber and into the exhaust system, also referred to as the exhaust tract, and flow through it. The exhaust system includes a burner, which can be supplied with fuel, particularly liquid fuel, and air, also referred to as burner air. For example, the exhaust system includes at least one additional component besides the burner, such as an exhaust aftertreatment element, for treating the exhaust gas.The exhaust aftertreatment element is or includes, for example, a catalyst, in particular an SCR catalyst, wherein, for example, selective catalytic reduction (SCR) can be catalytically supported and / or effected by means of the SCR catalyst, such that, for example, the SCR catalyst is catalytically active for the SCR process. In selective catalytic reduction, any nitrogen oxides contained in the engine exhaust are at least partially removed from the exhaust gas by reacting the nitrogen oxides with ammonia to form nitrogen and water. The ammonia is provided, for example, by a reducing agent, particularly a liquid one, which could be, for example, an aqueous urea solution. Furthermore, it is conceivable that the exhaust aftertreatment element is or includes a particulate filter. In particular, the particulate filter is a diesel particulate filter (DPF).The particulate filter can be used to filter out any particles, especially soot particles, that may be contained in the exhaust gas.

[0006] A burner is used to combust a mixture, also known as a burner mixture, which comprises the burner air and the fuel. For this purpose, the burner has, for example, a combustion chamber, also referred to as the main combustion chamber, in which the burner mixture can be combusted, in particular ignited and burned. The combustion chamber is specifically bounded by a chamber element, particularly a solid body, and in particular by an inner circumferential surface of the chamber element, especially directly. The combustion of the burner mixture, which takes place particularly in the combustion chamber, produces burner exhaust gas, also referred to as burner exhaust gas.The burner exhaust gas can, for example, flow out of the burner, particularly from the combustion chamber, and into an exhaust duct of the exhaust system through which the engine exhaust gas flows, especially at an inlet point located upstream of the aforementioned component in the direction of flow of the engine exhaust gas through the exhaust system, i.e., the exhaust duct. Thus, the component is permeable to the burner exhaust gas. For example, the burner exhaust gas mixes with the engine exhaust gas. Consequently, the burner exhaust gas, especially the burner exhaust gas mixed with the engine exhaust gas, can flow through the component, thereby heating it up.In particular, it is conceivable that the burner exhaust gas can flow out of the combustion chamber and into the exhaust duct, thereby mixing with the engine exhaust gas and / or gas flowing through the exhaust duct, thus heating the engine exhaust gas or the gas. In other words, this can result in a particularly high temperature of the engine exhaust gas or the gas, also known as the exhaust gas temperature.In particular, the gas can be, for example, air flowing through the exhaust duct, especially while the internal combustion engine is being towed, i.e., when the engine is not firing and therefore not producing exhaust gas. In this case, the gas, especially the air, is conveyed through the exhaust duct, particularly by the towed engine. The high exhaust gas temperature can heat and / or keep the component warm, as the burner exhaust and, for example, the engine exhaust or the gas flow through the component. Thus, for example, the burner exhaust from the combustion chamber is introduced into the exhaust duct at the aforementioned inlet point, and consequently into the engine exhaust or gas flowing through the exhaust duct.

[0007] The exhaust system includes a supply line through which the combustion air, which supplies or is supplied to the burner, flows. The exhaust system also includes an air pump, specifically provided in addition to the burner and the internal combustion engine, by means of which the combustion air can be conveyed through the supply line and thus delivered to the burner, thereby supplying it with combustion air.

[0008] For example, the air pump is designed as an electric air pump, which is electrically operable or operated in order to supply the burner with burner air, thus conveying the burner air through the supply line and towards the burner.

[0009] To achieve particularly advantageous burner operation, the invention provides that the exhaust system includes a branch line, in particular in addition to the supply line, by means of which, as will be explained in more detail below, at least a portion of the air flowing through the supply line can be diverted from the supply line at a branch point. It is particularly provided that the branch line can be fluidically connected to, or is connected to, the supply line at the branch point, with the branch point being arranged downstream of the air pump and upstream of the burner in the direction of airflow through the supply line.

[0010] The exhaust system also features a combination valve that can be switched between a first switching state and at least one second switching state. In the first switching state, the branch line is, in particular completely, fluidically separated from the supply line, and in the first switching state, the air supplied by the air pump (burner air) is allowed to flow through the supply line and towards the burner.This means that when, by means of the air pump, in particular by operating the air pump, the air is conveyed through the supply line and conveyed towards the burner, i.e. conveyed in the direction of the burner, while the combination valve is in the first switching state, the branch line, in particular completely, is fluidically separated from the supply line, and the air, in particular all, conveyed by means of the air pump and flowing through the supply line, in particular as the burner air, flows to the burner, in particular without being branched off from the supply line at the branch line.

[0011] In the second switching state, the branch line is fluidically connected to the supply line at the branch point located downstream of the air pump and upstream of the burner, whereby at least a part of the air conveyed by the air pump and, in particular, at least partially flowing through the supply line, can be diverted from the supply line and, in particular, introduced into the branch line by means of the branch line at the branch point, and, in particular, can be introduced into the branch line.In other words, if the air pump, particularly when operating the air pump, draws air through the supply line while the combination valve is in the second switching state, then at least the aforementioned portion of the air drawn by the air pump and flowing at least partially through the supply line is diverted from the supply line at the branch point and introduced into the branch line. This means, for example, that the portion of air diverted from the supply line and introduced into the branch line does not flow to the burner. This means that the burner is not supplied with the diverted portion of air.The invention thus makes it possible to operate the air pump and thereby convey air by means of the air pump and thereby generate a particularly high mass and / or volume flow of air and / or a particularly high pressure of air by means of the air pump, without the air pump, for example designed as a compressor or operating as a compressor, reaching its stalling limit and without the burner being supplied with all the air conveyed by means of the air pump, so that the combination valve can be in the second switching state while the air pump is being operated and thus generates the high mass and / or volume flow of air and / or the high pressure of air.In other words, if, for example, the pump is operated while the valve element is in the second switching state, so that the pump conveys the air, in particular at least through part of the supply line, while the combination valve is in the second switching state, then the air pump can generate a particularly high mass and / or volume flow of air and / or a particularly high pressure of air without the burner being supplied with all the air conveyed by the air pump, since at least the part of the air conveyed by the air pump is diverted from the supply line at the branch point, also referred to as the branch point, and thus prevented from flowing to the burner.This can be desirable and / or advantageous for several reasons, for example: The burner exhaust gas can flow out of the combustion chamber and into the exhaust duct if it has a higher pressure than the engine exhaust gas flowing through the duct. If the engine exhaust pressure is greater than the burner exhaust pressure, the engine exhaust gas can, for example, shut down the burner, as it can flow from the exhaust duct into the combustion chamber or burner and extinguish a flame that is burning the fuel-air mixture. Therefore, it is advisable that the pressure of the burner exhaust gas is always greater than the pressure of the engine exhaust gas when the burner is operating or is intended to operate – that is, when the burner is supplying or is intended to supply the burner exhaust gas.The pressure of the burner exhaust depends on the pressure of the air (burner air), which is generated by the air pump. The air pump draws air through the supply line and compresses it. If no countermeasures are taken, it can happen, for example, that the burner is initially operated with a higher pressure of the burner exhaust than the pressure of the engine exhaust. This can lead to a sudden increase in engine exhaust pressure, which, as described above, can result in the burner shutting down. This is because the air pump may not be able to increase the air pressure, and therefore the burner exhaust pressure, quickly enough to prevent the burner from shutting down unexpectedly due to the increased engine exhaust pressure, thus extinguishing the flame.Put simply, the air pump alone cannot react quickly enough to a sudden increase in engine exhaust pressure to keep the burner running. The invention now makes it possible to react sufficiently quickly to, in particular, sudden increases in engine exhaust pressure. For this purpose, the burner is initially operated with a high air flow rate while the combination valve is in its second switching state. The pump is then operated while the combination valve is in its second switching state to draw air, specifically to the burner, thus supplying it with air (burner air).The air pump can generate a suitably high mass and / or volume flow rate of air and / or a suitably high air pressure without supplying the burner with all of the air delivered by the air pump and / or without supplying the burner with the high air pressure, since at least some of the air is diverted from the supply line at the branch point and fed into the branch line. Supplying the burner with all of the air delivered by the air pump and / or with the high air pressure (burner air) generated by the air pump may be undesirable. In other words, by operating the burner and delivering air by the air pump while the combination valve is in the second switching state, advantageous burner operation can be achieved.If, for example, there is a sudden increase in engine exhaust pressure, the combination valve can simply be switched from the second to the first switching position. As a result, the burner is supplied with all the air delivered by the air pump and / or with the high pressure of the air (burner air) generated by the air pump, allowing for a sufficiently rapid response to the sudden increase in engine exhaust pressure. This sudden increase in engine exhaust pressure then does not lead to an undesirable extinguishing of the flame, but rather the burner can be kept operating efficiently.Adjusting or changing the operation of the air pump in such a way that the volume and / or mass flow of air and / or the pressure of the air produced by the air pump is increased, can, for example, be done in addition to switching the combination valve from the second switching state to the first switching state, or it can be omitted, so that, for example, the sole means of adequately and sufficiently quickly responding to a sudden increase in the pressure of the engine exhaust gas is the sole means of switching the combination valve from the second switching state to the first switching state.

[0012] To achieve a particularly advantageous, and especially efficient, operation, the invention further provides that the branch line is fluidically connected to the supply line at an inlet point located upstream of the air pump, thereby allowing the diverted portion of the air to be discharged from the branch line at the inlet point and, in particular, reintroduced into the supply line. The branch line is thus designed as a recirculation line and functions as a recirculation channel, since the portion of air diverted from the supply line and introduced into the branch line is guided by the branch line from the branch point, in particular back, to the inlet point and (re)introduced into the supply line at the inlet point.Since the inlet point is located upstream of the air pump, the diverted air from the branch line flows upstream of the air pump into the supply line and can then be fed back to the air pump.

[0013] The burner, for example, has at least one channel through which the burner air flows, which is arranged, for example, upstream of the combustion chamber in the direction of flow of the burner air through the channel. For example, a swirling flow of the burner air through the channel can be created, so that the burner air exhibits a swirling flow, at least within the combustion chamber. This allows the burner air to be mixed particularly effectively with the fuel, resulting in a particularly advantageous formation of the burner mixture, also known as mixture formation or mixture preparation.The channel has, for example, at least or exactly, an outlet opening through which the burner air can flow, and through which the burner air can be discharged, in particular from the channel, and introduced into the combustion chamber. The burner has, for example, a closure element, designed, for example, as a closing flap, which is movable, in particular pivotable, between a closed position and at least one open position, particularly relative to the chamber element and / or relative to the channel and / or relative to the outlet opening. In the closed position, the outlet opening, and thus the channel, is fluidically separated from the combustion chamber by means of the closure element. In the open position, the closure element releases the outlet opening and the channel, so that in the open position the outlet opening and the channel, i.e., the channel via the outlet opening, are fluidically connected to the combustion chamber.In the closed position, the sealing element prevents engine exhaust from flowing from the exhaust duct through the combustion chamber into the outlet opening and the duct when the burner is deactivated and therefore not producing any burner exhaust gas. This prevents components such as soot and / or particles contained in the engine exhaust gas from accumulating or settling in unwanted areas of the burner and thus clogging the outlet opening or the duct.

[0014] When the burner is started, that is, switched from its deactivated to its activated state, the shut-off element opens, moving from the closed to the open position. Furthermore, the pressure of the burner air against the back pressure of the engine exhaust (also known as exhaust back pressure) should then be high enough, or built up, so that the burner air, and consequently the burner exhaust, can overcome the engine exhaust and thus flow out of the combustion chamber and into the exhaust duct. For example, it is intended that, during and / or after the opening of the shut-off element, the burner air, or rather its pressure, is built up against the exhaust back pressure, and then an ignition element is activated. Only then is the fuel introduced, particularly into the duct and / or the combustion chamber, especially by injection, to activate the burner, that is, to ignite and burn the mixture and subsequently produce the burner exhaust.The critical factor is typically the build-up of the combustion air volume and / or mass flow rate and / or pressure when the shut-off element is opened, since, as previously described, the combustion air pressure or mass flow rate must overcome the exhaust back pressure to activate the burner. Any air pump that does not operate on the basis of a piston compressor, but rather on the basis of a radial or axial compressor wheel, initially requires a positive scavenging gradient to build up the combustion air pressure or mass flow rate. This means, in particular, that the combustion air pressure, referred to as atmospheric pressure, should be, or even must be, greater than the engine exhaust pressure.If a positive scavenging gradient is not present, flow separation at the impeller blades of an air pump (e.g., those designed as compressor blades) limits the air delivery and thus the development of a positive scavenging gradient, especially with increasing air mass flow. Only when the air pump (e.g., designed as a compressor or operating as a compressor) and the air mass flow through the pump reach a certain operating point with a corresponding efficiency is a stable flow situation actually achieved, with a physical coupling of pressure and air flow rate within a certain operating range of the air pump. If the exhaust back pressure, i.e., the pressure of the engine exhaust, increases, flow separation (also known as stall) can occur again at the impeller of the air pump, and the air mass flow collapses abruptly.The aforementioned disadvantages and problems can only be avoided by the invention. For example, the combination valve, particularly in the first switching state, can prevent unwanted backflow, i.e., an undesired return flow of the engine exhaust gas at high back pressure. Furthermore, the combination valve, particularly in the second position, can open the branch line. This allows or enables, especially while the closing element is in the closed position, the operation of an air pump, designed or operating as a compressor, at an operating point that results in an advantageously high volume and / or mass flow rate of the air and / or an advantageously high air pressure, particularly without the air pump reaching its stalling limit.In particular, the combination valve, especially in the second switching state, makes it possible to operate the air pump in such a way that the operation of the air pump results in an advantageously high mass and / or volume flow of air and / or a particularly high pressure of air, for example completely independent of the pressure of the engine exhaust gas, also referred to as back pressure, and / or for example completely independent of whether the sealing element is open or closed.

[0015] Thus, for example, the air pump is operated and air is drawn in by the air pump, while the combination valve is initially in the second switching state. This allows for a suitably high mass and / or volume flow rate of air and / or a particularly high air pressure to be built up. Once the mass and / or volume flow rate and / or air pressure is sufficiently high and, for example, the efficiency of the air pump is particularly advantageous, especially at its optimum, the combination valve is switched from the second switching state to the first switching state.

[0016] The branch line is a recirculation line. In other words, the branch line functions as a recirculation duct. By switching the combination valve from the second switching state to the first switching state, the volume and / or mass flow of air in the branch line is reduced to zero, particularly in parallel with the increasing mass and / or volume flow and / or pressure of the air towards the burner. This is because switching the combination valve from the second switching state to the first state fluidically isolates the branch line from the supply line and, in particular, from the air pump. The branch line is, or forms, a recirculation system, which offers considerable application flexibility and, compared to conventional solutions, increases system availability at high exhaust back pressures.Furthermore, an advantageous, fast and robust start-up process can be implemented, through which the initially deactivated burner is activated.

[0017] To achieve a particularly advantageous operation, one embodiment of the invention provides that, in the second switching state, the branch line is fluidically connected to the supply line at the branch point. This allows the first portion of the air pumped by the air pump, which flows at least partially through the supply line, to be diverted from the supply line and, in particular, introduced into the branch line. Furthermore, it is preferably provided that, in the second switching state, a second portion of the air pumped by the air pump is allowed to flow through the supply line and to the burner.Thus, when the combination valve is in the second switching state, the burner is supplied with the second part of the air, which, for example, makes it particularly advantageous to start the burner and / or to open the shut-off element advantageously, especially to start the burner.

[0018] It has proven particularly advantageous if the combination valve can be switched to a third switching state. In the third switching state, the branch line is, in particular, completely, fluidically isolated from the supply line, and in the first switching state, the supply line is also, in particular, completely, fluidically isolated from the air pump.

[0019] A second aspect of the invention relates to a motor vehicle, also referred to simply as a vehicle, preferably designed as a motor car, in particular as a passenger car or as a commercial vehicle, which has an internal combustion engine by means of which the motor vehicle can be propelled. Furthermore, the motor vehicle, in particular the internal combustion engine, has an exhaust system through which exhaust gas from the internal combustion engine flows, according to the first aspect of the invention. Advantages and advantageous embodiments of the first aspect of the invention are to be regarded as advantages and advantageous embodiments of the second aspect of the invention, and vice versa.

[0020] Further advantages, features, and details of the invention will become apparent from the following description of a preferred embodiment and from the drawing. The features and combinations of features mentioned above in the description, as well as those mentioned below in the figure description and / or shown in the figures alone, can be used not only in the combinations specified, but also in other combinations or individually, without departing from the scope of the invention.

[0021] The drawing shows in: Fig. 1 a schematic representation of an exhaust system for an internal combustion engine of a motor vehicle; Fig. 2 a schematic sectional view of a combination valve of the exhaust system, wherein the combination valve is in a first switching state; Fig. 3 a schematic sectional view of the combination valve in a second switching state of the combination valve; and Fig. 4 a schematic sectional view of the combination valve in a third switching state of the combination valve.

[0022] In the figures, identical or functionally equivalent elements are provided with the same reference symbols.

[0023] Fig. Figure 1 shows a schematic representation of an exhaust system 10 for an internal combustion engine 12, also referred to as a motor, internal combustion engine, or combustion power unit, of a motor vehicle, preferably a car, which is also referred to as a vehicle. This means that the motor vehicle, in its fully manufactured state, has the internal combustion engine 12 and can be driven by means of the internal combustion engine 12. For example, the internal combustion engine 12 is designed as a diesel engine. A tank 14, also referred to as a fuel tank, is associated with the internal combustion engine, in which a fuel, in particular a liquid fuel, is stored or held for operating the internal combustion engine 12 during its combustion operation. The fuel is, for example, diesel fuel, which is also simply referred to as diesel.A low-pressure pump 16 transfers fuel from tank 14 to a high-pressure pump 18. The high-pressure pump 18 pressurizes the fuel and delivers it to injectors 20. Specifically, the high-pressure pump 18 delivers the fuel to a fuel distribution element (not shown), also referred to as a rail, which is common to the injectors 20. The high-pressure fuel can be temporarily stored in the fuel distribution element. The high-pressure fuel stored in the fuel distribution element is then distributed to the injectors 20, allowing the fuel to be injected directly into the respective combustion chambers and thus into the respective cylinders 22 of the internal combustion engine 12.Each cylinder 22 partially limits the respective combustion chamber of the internal combustion engine 12.

[0024] The internal combustion engine 12 has an intake tract 24, also referred to as the intake tract, through which air flows. The air flowing through the intake tract 24 is also called fresh air or combustion air. The fresh air flowing through the intake tract 24 is directed to and into the combustion chambers and thus to the cylinders 22. A fuel-air mixture is thus formed from the fuel and the fresh air, which is ignited in the respective combustion chamber and thus in the respective cylinder 22, in particular by auto-ignition, and subsequently burned. This results in exhaust gas from the internal combustion engine 12, also referred to as engine exhaust. The internal combustion engine 12 has an exhaust tract 26 through which the engine exhaust gas from the combustion chambers flows, which is, for example, a component of the exhaust system 10.The exhaust system 10 is permeable to the engine exhaust gas from the combustion chambers. The respective fuel-air mixture comprises fresh air and fuel. The internal combustion engine 12 also includes a charging device 28, which has at least one exhaust gas turbocharger 30. The exhaust gas turbocharger 30 comprises a compressor 32 arranged in the intake tract 24, by means of which the fresh air flowing through the intake tract 24 can be compressed. The exhaust gas turbocharger 30 also comprises a turbine 34 arranged in the exhaust tract 26 and driven by the engine exhaust gas, by means of which the compressor 32 can be driven, in particular via a shaft of the exhaust gas turbocharger 30. The exhaust system 10 has an exhaust aftertreatment device 36, which may, for example, comprise a nitrogen oxide storage catalyst 38, a particulate filter 40, and an SCR catalyst 42.The nitrogen oxide storage catalyst 38, also referred to as a storage catalyst, storage catalytic converter, or NOx storage catalyst, is designed to capture, retain, and, in particular, store any nitrogen oxides (NOx) contained in the engine exhaust gas. The nitrogen oxide storage catalyst 38, the particulate filter 40, and the SCR catalyst 42 are components of the exhaust system 10. These components are arranged sequentially in the direction of flow of the engine exhaust gas through the exhaust system 10, i.e., in series with one another. The engine exhaust gas can flow through the components. In this context, the components are exhaust aftertreatment elements by means of which the engine exhaust gas is or can be treated. The storage catalyst 38 is arranged upstream of the particulate filter 40 in the direction of flow of the engine exhaust gas through the exhaust system 10, which in turn is arranged upstream of the SCR catalyst 42.The particulate filter 40 is designed, for example, to filter out any particles contained in the exhaust gas, especially soot particles, from the engine exhaust. In particular, if the internal combustion engine 12 is a diesel engine, the particulate filter 40 is designed, for example, as a diesel particulate filter (DPF).

[0025] Furthermore, a metering device 44 is provided, by means of which a reducing agent, in particular a liquid, such as an aqueous urea solution, can be introduced or is introduced into the exhaust gas flowing through the exhaust system 10 at a point S1, also referred to as the injection point. The exhaust system 10 has at least one exhaust channel through which the engine exhaust gas flows, and the reducing agent can be introduced, in particular injected, into the exhaust channel and thus into the engine exhaust gas flowing through the exhaust channel, particularly at point S1, for example, by means of the metering device 44. In the present case, the exhaust system 10 has a mixing chamber 46, which is arranged downstream of point S1 and upstream of the SCR catalyst 42.In the mixing chamber 46, for example, the reducing agent introduced into the exhaust channel and thus into the engine exhaust can mix with the exhaust gas (engine exhaust) flowing through the exhaust system 10 or the exhaust channel.

[0026] The exhaust system 10 also includes a burner 48. The burner 48 can be supplied with a fuel, particularly a liquid fuel, and with air, also referred to as burner air. For example, the fuel mentioned above is referred to as the fuel. By means of the burner 48, a mixture, also referred to as a burner mixture, can be formed from the burner air, with which the burner 48 can be supplied, is supplied, or was supplied, and from the fuel, with which the burner 48 can be supplied, was supplied, or is supplied. The burner mixture can be combusted by means of the burner 48, in particular by forming a flame 50. The mixture is formed, ignited, and combusted in a combustion chamber of the burner. To protect against contamination, an outlet opening of the burner towards the combustion chamber is sealed fluid-tight by means of a sealing element when the burner is not in use.As soon as the burner is needed, the shut-off element can open the discharge opening, allowing air and fuel to flow into the combustion chamber. The combustion of the burner mixture results, for example, in exhaust gas from burner 48, also known as burner exhaust. It is evident that the burner mixture comprises the burner air and the fuel by which burner 48 is supplied, is supplied, or was supplied. In particular, the burner exhaust gas can flow out of burner 48 and into the exhaust duct, subsequently flowing through the exhaust duct, i.e., the exhaust system 10. It is evident that the burner exhaust gas can flow through the respective component, so that, for example, at least one of the components can be heated and / or kept warm by means of the burner exhaust gas.It is evident that the burner 48, in particular an inlet point where the burner exhaust gas and, for example, the flame 50 can be introduced into the exhaust duct and thus into the engine exhaust flowing through the exhaust duct, is arranged upstream of the nitrogen oxide storage catalyst 38 and / or upstream of the particulate filter 40 and / or upstream of the SCR catalyst 42. This allows, for example, the nitrogen oxide storage catalyst 38 and / or the particulate filter 40 and / or the SCR catalyst 42 to be heated and / or kept warm.

[0027] To supply the burner 48 with fuel, a fuel line 52 is provided. The fuel line 52 is fluidically connected at a first connection point V1 to a further fuel line 54, through which the fuel can be conveyed from the tank 14 to the injectors 20 or to the fuel distribution element. The connection point V1 is arranged downstream of the low-pressure pump 16 and upstream of the high-pressure pump 18 in the direction of fuel flow through the further fuel line 54. At least a portion of the fuel flowing through the further fuel line 54 can be diverted from the further fuel line 54 and introduced into the fuel line 52.The fuel diverted from the further fuel line 54 via fuel line 52 can flow through fuel line 52 and is conveyed as fuel via fuel line 52 to the burner 48, thus supplying the burner 48 with the fuel flowing through fuel line 52. In this way, the burner 48 is supplied with fuel from tank 14, with the fuel being used as the fuel.

[0028] Furthermore, the burner 48 is equipped with its own electrically operated air pump 56, which is provided in addition to the internal combustion engine 12 and thus in addition to the charging device 28. A supply line 58 is also provided, in which the air pump 56 is located. The air pump 56 allows the burner 48 to be supplied with air, as burner air, independently of the internal combustion engine 12 and thus independently of the charging device 28. In other words, the supply line 58 is permeable to air, so that the burner 48 can be supplied with the air flowing through the supply line 58, which serves as burner air. The air pump 56 can pump the air flowing through the supply line 58.Thus, by means of the air pump 56, the burner air can be conveyed through the supply line 58 and conveyed to the burner 48 in order to supply the burner 48 with the burner air.

[0029] A first valve element 60 is arranged in the fuel line 52, by means of which the quantity of fuel with which the burner 48 can be supplied or is supplied is adjustable, in particular controllable. A second valve element 62 is arranged in the supply line 58, in particular downstream of the air pump 56, by means of which the quantity of air with which the burner 48 can be supplied or is supplied is adjustable, in particular controllable.

[0030] For example, an electronic computing device, also referred to as a control unit 64, is provided, specifically assigned to the burner 48. The control unit 64 is designed, for example, to actuate, in particular control or regulate, the first valve element 60. This allows, for example, the amount of fuel supplied to the burner 48 to be set, in particular regulated or controlled, by actuating the first valve element 60 via the control unit 64. Additionally, the second valve element 62 can be actuated, in particular controlled or regulated, by the control unit 64. Thus, for example, the control unit 64 can adjust, in particular control or regulate, the amount of air flowing through the supply line 58 to supply the burner 48 by actuating, in particular controlling or regulating, the second valve element 62.In particular, this allows the ratio of burner air to fuel, also known as the combustion air ratio, to be adjusted to meet specific requirements.

[0031] In order to achieve particularly advantageous operation of the burner 48, the exhaust system 10 has a branch line 68, which is provided in addition to the supply line 58 and is at least partially separate from the supply line 58. Furthermore, the exhaust system 10 has a third valve element 70, which can be controlled by the control unit 64 and controls the airflow through the branch line 68.

[0032] The branch line 68 branches off at a branch point AS downstream of the air pump 56 and bypasses the air pump 56, wherein the branch line 68 is fluidically connected to the supply line 58 at an inlet point ES upstream of the air pump 56.

[0033] In the Fig. 2, Fig. 3 to Fig. According to the invention, the second valve element 62 and the third valve element 70 are combined to form a combination valve 72. In the embodiment shown in the figures, the combination valve 72 is divided between a Fig. 2 shown, first switching state ST1, one in Fig. 3 shown, second switching state ST2, one in Fig. The third switching state ST3 shown in section 4 can be switched.

[0034] In the combination valve 72, the second valve element 62 and the third valve element 70 are provided in a housing 74. The housing 74 connects, for example, to the air pump 56, with the air supplied by the air pump 56 first being supplied to the housing 74. The supply line 58 and the branch line 68 are connected to the housing 74, so that the air supplied by the air pump 56 can flow into the supply line 58 and / or into the branch line 68. The combination valve 72 includes a control element 76 common to both valve elements 62 and 70. The control element 76 has a control disc 78, which opens or closes the supply line 58 for the air supplied by the air pump 56 to the burner 48. The control element 76, together with the control disc 78 and the supply line 58, forms the second valve element 62.Furthermore, the control element 76 has, in addition to the control plate 78, a piston element 80 with a control edge 82. The branch line 68 can be opened or closed by means of the piston element 80 with its control edge 82. The control element 76, together with the piston element 80 and its control edge 82 and the branch line 68, forms the third valve element 70. The control element 76 can be moved back and forth by an actuator (not shown in detail), so that the control element 76 in the housing 74 can, in a first direction towards the supply line 58 downstream of the air pump 56, close the supply line 58 with its control plate 78 and simultaneously close the branch line 68 with the piston element 80. When the control element 76 is moved in a second direction opposite to the first, the control plate 78 can open the supply line 58 but keep the branch line 68 closed.If the control element 76 is moved further in the second direction, the supply line 58 remains open and the branch line 68 can be opened. In the . Fig. 2, Fig. 3 to Fig. Figure 4 shows that an air filter 84 may be arranged in the supply line 58 upstream of the air pump 56.

[0035] Fig. Figure 2 shows a first switching state of the combination valve 72, designated ST1. In this state, the air pump 56 is fluidically connected to the supply line 58, while the branch line 68 remains closed by the piston element 80. The control element 76 has been moved in the second direction, so that the control plate 78 has opened the supply line 58. This allows air to be supplied from the air pump 56 to the burner 48, as illustrated by arrow 86.

[0036] Fig. Figure 3 shows a second switching state of the combination valve 72, labeled ST2. In this state, the air pump 56 is fluidically connected to the supply line 58 (arrow 86) and the branch line 68, illustrated by arrow 88. The control element 76 has moved further in the second direction, so that the control plate 78 has moved further away from the supply line 58, and the piston element 80 of the control element 76 at least partially opens the branch line 68. The degree of opening of the branch line 68 can be set using the control edge 82 of the piston element 80, depending on how far the control element 76 is moved in the first or second direction. By opening the branch line 68, the air pumped by the air pump 56 can be pumped back from the branch point AS downstream of the air pump 56 through the branch line 68 to the inlet point ES upstream of the air pump 56.

[0037] Fig.Figure 4 shows a third switching state of the combination valve 72, designated ST3. In this state, the supply line 58 and the branch line 68 are, in particular completely, fluidically isolated from the air pump 56. The control element 76 has been moved in the first direction, whereby the control plate 78 closes the supply line 58 and the piston element 80 closes the branch line 68, so that no air can be conveyed from the air pump 56 into the supply line 58 and thus to the burner 48, and no air can be conveyed into the branch line 68. Reference symbol list 10 Exhaust system 12 Internal combustion engine 14 Tank 16 Low-pressure pump 18 High-pressure pump 20 injectors 22 cylinders 24 Intake tract 26 Exhaust system 28 Charging device 30 exhaust gas turbochargers 32 compressors 34 Turbine 36 Exhaust aftertreatment system 38 Nitrogen oxide storage catalyst 40 particulate filters 42 SCR catalyst 44 Dosing unit 46 Mixing chamber 48 burners 50 flames 52 Fuel line 54 Fuel line 56 Air pump 58 Supply line 60 first valve element 62 second valve element 64 Control unit 68 Branch line 70 third valve element 72 Combination valve 74 cases 76 Control element 78 control plates 80 piston elements 82 Control edge 84 air filters 86 Arrow 88 Arrow AS Junction ES induction point S1 entry point ST1 first switching state ST2 second switching state ST3 third switching state V1 liaison point QUOTES INCLUDED IN THE DESCRIPTION

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

[0000] DE 10 2019 008 956 A1

[0002] DE 10 2021 001 580 A1

[0002]

Claims

Exhaust system (10) for an internal combustion engine (12) of a motor vehicle, with a burner (48) supplied with air and fuel, by means of which a mixture comprising air and fuel is to be burned, with a supply line (58) through which air can flow, via which the burner (48) can be supplied with the air flowing through the supply line (58), and with an air pump (56) arranged in the supply line (58), by means of which the air can be conveyed through the supply line (58) and conveyed to the burner (48) in order to supply the burner (48) with air, characterized in that: - a branch line (68) is provided;- a combination valve (72) is provided, which is switchable between a first switching state (ST1), in which the branch line (68) is fluidically separated from the supply line (58) and the air supplied by the air pump (56) is allowed to flow through the supply line (58) and towards the burner (48), and at least a second switching state (ST2), in which the branch line (68) is fluidically connected to the supply line (58) at a branch point (AS) arranged downstream of the air pump (56) and upstream of the burner (48), whereby at least a part of the air supplied by the air pump (56) can be diverted from the supply line (58) by means of the branch line (68) at the branch point (AS);and- the branch line (68) is fluidically separated from the supply line (58) at an inlet point (ES) arranged upstream of the air pump (56), whereby the diverted part of the air can be discharged from the branch line (68) at the inlet point (ES) and introduced into the supply line (58). Exhaust system (10) according to claim 1, characterized in that in the second switching state (ST2): - the branch line (68) is fluidically connected to the supply line (58) at the branch point (AS), whereby the first part of the air supplied by the air pump (56) can be branched off from the supply line (58) by means of the branch line (68) at the branch point (AS); and - a second part of the air supplied by the air pump (56) can flow through the supply line (58) and towards the burner (48). Exhaust system (10) according to claims 1 or 2, characterized in that the combination valve (72) can be switched to a third switching state (ST3) in which: - the supply line (58) is fluidically separated from the air pump (56); and - the branch line (68) is fluidically separated from the supply line (58). Motor vehicle, with an internal combustion engine (12) by means of which the motor vehicle can be driven, and with an exhaust system (10) through which exhaust gas of the internal combustion engine (12) flows according to one of the preceding claims.

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