Method for operating a burner for a motor vehicle

Abstract

The invention relates to a method for operating a burner for an exhaust tract through which exhaust gas from an internal combustion engine of a motor vehicle flows, wherein the burner has a combustion chamber in which a mixture comprising air and a fuel is to be ignited and thereby combusted. The burner comprises at least one channel through which at least a portion of the air can flow, which has an outflow opening through which at least the portion of the air flowing through the channel can flow, via which at least the portion of the air can be discharged from the channel and fed to the combustion chamber.The burner comprises a closure element which is movable relative to the outflow opening between at least one closed position closing the outflow opening as a first position, in which the channel is fluidically separated from the combustion chamber, and at least one open position releasing the outflow opening as a second position, in which the channel is fluidically connected to the combustion chamber.

Description

[0001] The invention relates to a method for operating a burner for an exhaust tract through which exhaust gas from an internal combustion engine of a motor vehicle can flow, according to the preamble of patent claim 1.

[0002] Such a method for operating a burner for an exhaust tract through which exhaust gas from an internal combustion engine of a motor vehicle can flow is already known, for example, from DE 10 2021 001 580 A1. In the method, the burner has a combustion chamber in which a mixture is to be ignited and thereby burned, the mixture comprising air and a fuel. In the method, the burner has at least one channel through which at least part of the air can flow, which channel has an outflow opening through which at least the part of the air flowing through the channel can flow, via which at least part of the air can be discharged from the channel and fed to the combustion chamber. In the method, the burner also has a closure element which is movable relative to the outflow opening between at least one closed position closing the outflow opening and at least one open position releasing the outflow opening.The closed position is also referred to as the first position. In the closed position, the channel is fluidically separated from the combustion chamber by the closure element. The open position is also referred to as the second position. In the open position, the channel is fluidically connected to the combustion chamber.

[0003] Furthermore, DE 10 2019 008 954 A1 discloses a method for heating at least one exhaust gas aftertreatment device arranged in an exhaust tract through which exhaust gas of an internal combustion engine can flow, of a motor vehicle comprising the internal combustion engine and which can be driven by means of the internal combustion engine.

[0004] The object of the present invention is to further develop a method of the type mentioned at the outset in such a way that a particularly advantageous operation of the burner can be realized.

[0005] This object is achieved by a method having the features of patent claim 1. Advantageous embodiments with expedient further developments of the invention are specified in the remaining claims.

[0006] In order to further develop a method of the type specified in the preamble of patent claim 1 in such a way that a particularly advantageous operation of the burner can be realized, in particular also over a long service life of the burner, it is provided according to the invention that the closure element is moved at least from one of the positions to the other position as a function of a current position of the motor vehicle on the earth determined by means of a navigation system of the motor vehicle, which is also simply referred to as the vehicle.

[0007] The internal combustion engine is also referred to as an internal combustion engine, combustion engine or motor and is preferably designed as a reciprocating piston machine, i.e. as a reciprocating piston engine. The internal combustion engine can be used to drive the motor vehicle, which is preferably designed as a motor vehicle, in particular as a passenger car. When the internal combustion engine is fired, combustion processes take place in the internal combustion engine, in particular in at least one or more combustion chambers of the internal combustion engine, resulting in the exhaust gas of the internal combustion engine, also referred to as engine exhaust. The engine exhaust can flow out of the respective combustion chamber and into the exhaust tract and subsequently flow through the exhaust tract, also referred to as the exhaust system. At least one component, such as an exhaust aftertreatment element for aftertreating the exhaust gas, can be arranged in the exhaust tract.The exhaust gas aftertreatment element is or comprises, for example, a catalyst, in particular an SCR catalyst, wherein, for example, selective catalytic reduction (SCR) can be catalytically supported and / or effected by means of the SCR catalyst, so that, for example, the SCR catalyst is catalytically active for the SCR. During selective catalytic reduction, any nitrogen oxides contained in the engine exhaust gas are at least partially removed from the exhaust gas by the nitrogen oxides reacting with ammonia to form nitrogen and water during selective catalytic reduction. The ammonia is provided, for example, by a reducing agent, in particular a liquid one, which can be an aqueous urea solution. Furthermore, it is conceivable that the exhaust gas aftertreatment element is a particulate filter or comprises a particulate filter. Most particularly, the particulate filter is a diesel particulate filter (DPF).The particulate filter can be used to filter out any particles contained in the exhaust gas, particularly soot particles.

[0008] The burner has the combustion chamber, also referred to as the main combustion chamber, in which the mixture, also referred to as the burner mixture, can be ignited and thus burned. The mixture comprises the air, which is also referred to as combustion air, and the preferably liquid fuel. In particular, the combustion chamber is delimited, in particular directly, by a chamber element, which is in particular designed as a solid body, in particular by an inner circumferential surface of the chamber element. The combustion of the mixture, which takes place in particular in the combustion chamber, produces an exhaust gas from the burner, also referred to as burner exhaust gas.The burner exhaust gas can, for example, flow out of the combustion chamber and into the exhaust tract, i.e., for example, into an exhaust duct of the exhaust tract through which the engine exhaust gas can flow, in particular at an inlet point which is arranged, for example, upstream of the aforementioned component in the flow direction of the engine exhaust gas flowing through the exhaust tract or the exhaust duct. For example, the burner exhaust gas mixes with the engine exhaust gas. As a result, the burner exhaust gas, in particular the burner exhaust gas mixed with the engine exhaust gas, can, for example, flow through the component, whereby the component can be heated, i.e., warmed and / or kept warm. For example, the aforementioned duct and thus also the outflow opening can also be flowed through by the fuel, so that, for example, the fuel can be discharged from the duct via the outflow opening and fed to the combustion chamber.For example, an ignition device, in particular an electrically operated one, is provided, wherein the burner can comprise the ignition device. In particular, it is conceivable that the ignition device is arranged at least partially in the combustion chamber. By means of the ignition device, in particular in the combustion chamber and / or using electrical energy, at least one ignition spark for igniting the mixture can be provided, i.e. generated, so that the mixture, in particular in the combustion chamber, can be ignited in particular by means of the ignition spark. The ignition device can be designed, for example, as a spark plug or as a glow plug.

[0009] The channel is or comprises, for example, at least one swirl chamber, through which at least the aforementioned portion of the air can flow. The swirl chamber is designed to bring about a swirling flow of at least the portion of the air. Thus, it is preferably provided that the swirl chamber is arranged upstream of the combustion chamber in the flow direction of the air flowing through the channel. In particular, it is provided that the channel flow is arranged on the combustion chamber in the flow direction of the air flowing through the channel. When reference is made below to air, this means, unless otherwise stated, the air forming the mixture, in particular in the combustion chamber, and flowing through the channel and thus, for example, the swirl chamber, i.e. the air from which the mixture is formed in the combustion chamber of the burner, in particular together with the fuel.The swirl chamber, for example, has the aforementioned outlet opening, in particular as the only outlet opening. For example, the air flowing through the outlet opening can be discharged from the swirl chamber via the outlet opening and, for example, introduced into the combustion chamber. Thus, in particular, the combustion chamber is arranged downstream of the swirl chamber in the flow direction of the air flowing through the swirl chamber.The feature that the swirl chamber causes or can cause a swirl-shaped flow of at least the part of the air flowing through the channel and thus the swirl chamber, and thus the air moving at least the part of the air, is to be understood in particular as meaning that the air flowing through the channel and thus the swirl chamber flows through the swirl chamber in a swirl-shaped manner, and thus flows through at least a partial area of ​​the swirl chamber in a swirl-shaped manner, and / or the air flowing through the channel and thus the swirl chamber has the swirl-shaped flow at least in a flow area arranged downstream of the swirl chamber and outside the swirl chamber, which is arranged, for example, in the combustion chamber.In particular, it is conceivable that the air flowing through the channel and thus through the swirl chamber flows out of the swirl chamber via the outflow opening in a swirl-like manner and / or flows into the combustion chamber in a swirl-like manner, so that it is very preferably provided that the air flowing through the channel and thus through the swirl chamber exhibits the swirl-like flow at least in the combustion chamber. In particular, it is conceivable that the air flowing through the channel already exhibits the swirl-like flow in the swirl chamber, specifically at least in the aforementioned partial region of the swirl chamber.

[0010] For example, the burner can have an introduction element, in particular an injection element, which has at least or exactly one outlet opening through which the preferably liquid fuel can flow. In particular, it is conceivable for the introduction element to have a plurality of, in particular more than two, outlet openings through which the preferably liquid fuel can flow. By means of the introduction element, the fuel can be introduced, in particular injected, for example, into the channel, in particular into the swirl chamber, in particular directly, so that the outflow opening can also be flowed through, for example, by the preferably liquid fuel that has exited, in particular sprayed out, from the introduction element via the outlet opening and is thereby introduced, in particular injected, in particular directly, into the channel, in particular the swirl chamber.

[0011] Since the closure element fluidically blocks the outflow opening in its closed position and thus fluidically separates the channel from the combustion chamber, it can be prevented, for example, in the closed position that a fluid such as gas and / or particles from or from the combustion chamber flows through the outflow opening and thus penetrates the channel via the outflow opening. This can be prevented, for example, from the fluid or the particles penetrating the channel and, for example, excessively clogging or even blocking the outflow opening and / or the channel. Furthermore, it can be prevented, for example, from the fluid or the particles penetrating via the channel to the introduction element and undesirably impairing the introduction element, such as clogging or even blocking it. This can also ensure advantageous operation of the burner over a long service life.

[0012] The method according to the invention further makes it possible to move the closure element preventively and / or predictively, in particular to close it, that is to say to move it from the open position into the closed position, so that, for example, the closure element is already in the closed position when, for example, such an operating state of the internal combustion engine begins, in whose operating state, for example, the internal combustion engine is in operation which could fundamentally lead to an inflow of fluid and / or particles into the combustion chamber, so that, in principle and in particular if the closure element were not in the closed position, the fluid or the particles could penetrate into the channel via the outflow opening.

[0013] The operating state is, for example, overrun and / or full-load operation of the internal combustion engine. In particular, the following is conceivable: If, for example, the internal combustion engine is initially in overrun mode, in which, for example, the fired operation of the internal combustion engine is omitted, so that no combustion processes take place in the internal combustion engine and the internal combustion engine does not produce its engine exhaust gas, it is conceivable to operate the burner at least during part of the overrun mode, for example, to prevent excessive cooling of the aforementioned component.If, for example, a change occurs (also known as a mode change) in which the internal combustion engine switches from overrun mode to traction mode, in which the internal combustion engine is in its fired mode, the engine exhaust may contain particles such as soot particles during or as a result of the mode change. During and / or as a result of the mode change, the burner, for example, is deactivated. If the burner is activated, the closure element is in the open position, allowing the mixture in the combustion chamber to be combusted.If, for example, at the start of traction operation following overrun operation, into which the internal combustion engine was transferred during or as a result of the change of operating mode, i.e. a short period of time after the start of traction operation, the burner is deactivated and the closure element is opened, it could in principle happen that any soot particles contained in the engine exhaust gas as a result of the change of operating mode penetrate from the exhaust duct into the combustion chamber and from the combustion chamber via the outlet opening into the duct.However, this can now be avoided by the invention, since the invention makes it possible to close the initially open, i.e., open-positioned closure element depending on the determined current position, i.e., to move it from the open position to the closed position, before the operating mode change occurs, i.e., before the internal combustion engine is transferred from overrun mode to traction mode, i.e., before the traction mode of the internal combustion engine begins following overrun mode. In particular, it is possible, for example, to close the closure element depending on the current, determined position while still in overrun mode, so that the closure element is already in the closed position at the start of the traction mode of the internal combustion engine following overrun mode.

[0014] The invention is based in particular on the following findings and considerations: In order to achieve particularly low-emission operation of the internal combustion engine, in particular during a cold start of the internal combustion engine, the burner is used, by means of which the component can be heated up effectively and efficiently, in particular during a cold start of the internal combustion engine. This is particularly advantageous when the internal combustion engine is designed as a diesel engine. By means of the burner, the component can, for example, be kept in a favorable temperature range and / or brought into the temperature range in which the component can advantageously aftertreat the exhaust gas. The burner enables the component to be heated up and / or kept warm without causing significant emissions.The burner is typically not in operation, i.e., deactivated, when the internal combustion engine is operating with a sufficient load, particularly during traction. However, if the internal combustion engine is in overrun mode, for example, when the vehicle is traveling downhill, the burner is operated for at least part of the overrun to prevent excessive, undesirable cooling of the component. The closure element can be used to prevent fluid and / or particles from the engine exhaust from entering the channel via the combustion chamber around the exhaust opening while the burner is deactivated.

[0015] In endurance tests at high load, it has been shown that burner components such as the duct and the introduction element can be advantageously protected against excessive soot ingress, i.e., against excessive contamination by soot or soot particles from the engine exhaust, by the closure element, which is designed, for example, as a closure flap. However, particularly in or during transient operation of the internal combustion engine with a transition from overrun mode with the burner activated and the closure element open to traction mode, in particular full-load operation of the internal combustion engine with the burner deactivated and the closure element closed, soot ingress into the duct can occur if no countermeasures are taken, since the time until the closure element closes cannot occur without hysteresis.Thus, if no appropriate countermeasures are taken, soot may enter the channel during a period extending, for example, from a first point in time to a subsequent second point in time, particularly continuously and thus without interruption. At the first point in time, for example, the traction operation of the internal combustion engine, in particular full-load operation, begins, which follows the overrun operation, with the closure element still being open at the first point in time.For example, at the first time or at a third time between the first time and the second time, a movement of the closure element from the open position to the closed position is started, but for example the closure element only reaches the closed position at the second time, so that only from the second time, at which the internal combustion engine is already in traction mode, can the closure element be used to prevent excessive soot from entering the channel.

[0016] The method according to the invention now makes it possible to close the initially opened closure element before the first time, so that, for example, the closure element is already in the closed position at the first time. This can prevent excessive soot from entering the channel.

[0017] The method according to the invention is thus, for example, an operating strategy for operating the burner. The operating strategy determines, in particular calculates, for example as a function of the determined current position and thus, for example, topography-guided, from navigation data, in particular in combination with torque data, points in time at which or in which the change in operating mode, also referred to as load change, from overrun mode to traction mode, in particular in full-load operation, occurs or will occur. In particular, the torque data characterizes the torques to be provided by the internal combustion engine and intended to drive the motor vehicle. The torque data are provided, for example, by a drive train of the motor vehicle, also referred to as the operating train, whose drive train includes the internal combustion engine.The method can close the closure element in good time before the traction operation following the overrun operation begins, i.e. before, for example, a full-load impulse is caused by the driver of the motor vehicle, for example by actuating an accelerator pedal, and thus before an excessive soot mass flow can penetrate into the channel.

[0018] Alternatively or additionally, for example, at least one event location is stored in the navigation data and thus, for example, in a virtual map of the motor vehicle's surroundings, in particular on the earth. The event location is also referred to as a point of interest (POI) or event position. In particular, the event location is a map point, i.e. a location or point on the virtual map, whereby an emissions strategy can significantly benefit at the location if this emissions strategy knows that the motor vehicle is at the location, is driving past and / or has previously been and / or driven past the location. For example, the event position is a load change point with an emissions influence.Examples of the event location can be driving through a depression followed by a steep incline, crossing a mountain pass followed by a longer downhill ride, or a lifting of a speed limit, etc. The method according to the invention now makes it possible to advantageously move the closure element, in particular to close or open it, before the motor vehicle actually reaches the event location, so that, for example, the closure element is already in the closed or open position when the motor vehicle actually reaches the event location. In this way, for example, excessive soot entry into the duct can be advantageously avoided. In particular, the method makes it possible to avoid excessive sooting of the burner and in particular of the duct resulting from transient load changes in the internal combustion engine.

[0019] The event location is preferably a location where, for example, a load jump, in particular a full-load jump, of the internal combustion engine has previously occurred. Upon approaching the location again, the closure element can, for example, be closed, so that the closure element is already in the closed position when the motor vehicle actually reaches the event location. If a load jump, in particular a full-load jump, of the internal combustion engine actually occurs at the event position, also referred to as the event location, the closure element is then already in the closed position, so that excessive soot ingress into the channel resulting from the load jump can be avoided.

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

[0021] The drawing shows in the only Fig. 1 a flow diagram illustrating a method for operating a burner for an exhaust tract through which exhaust gas from an internal combustion engine of a motor vehicle can flow.

[0022] Fig.1 shows a flow diagram illustrating a method for operating a burner for an exhaust tract through which exhaust gas from an internal combustion engine of a motor vehicle flows. In the method, the burner has a combustion chamber in which a mixture is to be ignited and burned. The mixture comprises air, which is also referred to as burner air, and a preferably liquid fuel. In the method, the burner has at least one channel through which at least a portion of the air can flow, which channel, in particular precisely, has an outflow opening through which at least the portion of the air flowing through the channel can flow, via which outflow opening at least the portion of the air can be discharged from the channel and fed to the combustion chamber.Furthermore, in the method the burner has a closure element which is movable relative to the outflow opening between at least one closed position and at least one open position, in particular pivotable about a pivot axis. The closed position is also referred to as the first position. The open position is also referred to as the second position. In the closed position the outflow opening is fluidically blocked by the closure element, so that in the closed position the channel is fluidically separated from the combustion chamber by means of the closure element. In the open position the closure element releases the outflow opening, so that in the open position the channel is fluidically connected to the combustion chamber via the outflow opening.

[0023] In order to be able to realize particularly advantageous operation of the burner, in particular over a long service life of the burner, it is provided in a first step S1 of the method that a current position of the motor vehicle on earth is determined by means of a navigation system, also referred to as a navigation device or navigation system, of the motor vehicle, also simply referred to as the vehicle. In the navigation system, in particular in a data memory of the navigation system, a virtual map of, in particular, the current surroundings of the motor vehicle is stored, for example. In particular, depending on the virtual map, the current position of the motor vehicle on earth is determined, i.e., determined, by means of the navigation system, preferably with the aid of satellites.In a second step S2 of the method, the closure element is moved, in particular by means of an actuator, from one of the positions to the other position depending on the determined current position of the motor vehicle.

[0024] Depending on the determined current position of the motor vehicle on earth, it is determined, for example, in particular by means of an electronic computing device of the motor vehicle, that a load step of the internal combustion engine will occur in the future and thus, for example, when the motor vehicle is in a further position on earth in the future that is different from the current position. During or as a result of the load step, for example, the internal combustion engine is transferred from its overrun mode to its traction mode, in particular full-load mode. Depending on the determined load step, for example, the closure element is moved in such a way that the closure element is closed, i.e. moved from the open position to the closed position.This makes it possible for the closure element to be in the closed position already at the beginning of the load jump, so that excessive soot entry into the channel resulting from the load jump can be avoided. List of reference symbols S1 first step S2 second step 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 2021 001 580 A1

[0002] DE 10 2019 008 954 A1

[0003]

Claims

[1] Method for operating a burner for an exhaust tract through which exhaust gas from an internal combustion engine of a motor vehicle flows, in which the burner comprises: - a combustion chamber in which a mixture comprising air and fuel is to be ignited and thereby burned; - at least one channel through which at least part of the air can flow, which has an outflow opening through which at least part of the air flowing through the channel can flow, via which at least part of the air can be discharged from the channel and fed to the combustion chamber; and - a closure element which is movable relative to the outflow opening between at least one closed position closing the outflow opening as a first position, in which the channel is fluidically separated from the combustion chamber, and at least one open position releasing the outflow opening as a second position, in which the channel is fluidically connected to the combustion chamber; characterized by that the closure element is moved at least from one of the positions to the other position depending on a current position of the motor vehicle determined by means of a navigation system of the motor vehicle (step S2). [2] Method according to claim 1, characterized bythat, depending on the determined current position of the motor vehicle, at least one forecast value is determined which characterizes at least one torque to be provided by the internal combustion engine at at least one future point in time and intended to drive the motor vehicle, wherein the closure element is moved at least from one position to the other position depending on the forecast value. [3] Method according to claim 1 or 2, characterized bythat, depending on the determined current position of the motor vehicle, a future load jump of the internal combustion engine and / or a change of the internal combustion engine from a coasting operation to a pulling operation of the internal combustion engine is predicted, wherein the closure element is moved at least from one of the positions to the other position depending on the predicted load jump and / or depending on the predicted change. [4] Method according to one of the preceding claims, characterized by that at least one event position is stored in a virtual map of a current environment of the motor vehicle, wherein the closure element is moved from at least one of the positions to the other position depending on a relationship between the determined, current position and the event position. [5] Method according to claim 4, characterized bythat if the motor vehicle travels ahead of the relation-dependent movement of the closure element, the event position is stored in the virtual map. [6] Method according to claim 5, characterized by that during the journey the event position is stored in the virtual map as a function of at least one operating state of the internal combustion engine, which is in the operating state at a time when the motor vehicle is at the event position.

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