DE102023211702A1 - Method, computing unit and computer program for operating a burner - Google Patents

Abstract

The invention relates to a method (200) for operating a burner (110), in particular an exhaust gas burner in an exhaust system (100) downstream of an internal combustion engine (120), wherein the method (200) comprises: supplying a predeterminable air flow (106, 108) to the burner (110), supplying a quantity of fuel (112) to the burner (110), igniting (114) the air-fuel mixture formed in the burner (110) by supplying the air flow and the quantity of fuel, whereby a burner exhaust gas is formed, receiving a sensor signal (3) containing information about a chemical composition of the burner exhaust gas, determining a controller output (2) for controlling (210) the chemical composition of the burner exhaust gas using the sensor signal in order to adjust the composition of the burner exhaust gas to a predeterminable target composition (1), determining an adaptation value (4) for a pre-control (220) of the fuel quantity (112) based on the controller output (2), and adjusting the supply of the fuel quantity (112) to the burner (110) using the adaptation value (4). Furthermore, a computing unit (140) and a computer program for carrying out such a method (200) are proposed.

Description

The present invention relates to a method for operating a burner, in particular an exhaust gas burner in an exhaust system downstream of an internal combustion engine, as well as a computing unit and a computer program for carrying out the method, and an arrangement comprising a burner and such a computing unit.

Background of the invention

To achieve legally prescribed emission limits, three-way catalysts (TWCs) can be used. These convert the relevant gaseous pollutants _NOx , HC, and CO into harmless products such as _N2 , _H2O , and _CO2 . For these catalytic reactions to proceed as intended, the temperatures in the catalyst must generally exceed the so-called light-off temperature of typically 300-400°C. Once this temperature is reached or exceeded, the catalyst converts the relevant pollutants almost completely (the so-called catalyst window).

To achieve this state as quickly as possible, so-called in-engine catalyst heating can be used. This reduces the efficiency of the gasoline engine by retarding the ignition angle, thereby increasing the exhaust gas temperature and the enthalpy input into the catalyst. At the same time, combustion stability can be ensured through adapted injection strategies (e.g., multiple injections).

In addition to these internal catalyst heating measures, external catalyst heating measures can also be used, for example, using electrically heated catalysts or exhaust gas burners. Such external heating measures are, for example, used in the DE 41 32 814 A1 and the DE 195 04 208 A1 described.

To further reduce emissions compared to conventional operation with internal engine heating measures, especially during cold starts, i.e. high loads on the internal combustion engine in a cold state without an idling phase, so-called catalytic converter burners have proven to be an extremely effective measure for accelerating the TWC light-off.

Disclosure of the invention

According to the invention, a method for operating a burner, in particular an exhaust gas burner in an exhaust system downstream of an internal combustion engine, as well as a computing unit and a computer program for implementing the method, and an arrangement comprising a burner and such a computing unit with the features of the independent patent claims are proposed. Advantageous embodiments are the subject of the dependent claims and the following description.

The invention utilizes the measure of adapting a burner's pilot control with respect to the air-fuel mixture supplied to it using a sensor signal containing information about the chemical composition of the burner exhaust gas (e.g., lambda signal) in order to relieve the control system. In some embodiments, the adaptation value determined for this purpose can also be used to diagnose a fault condition or a burner malfunction.

In detail, the method according to the invention for operating a burner, in particular an exhaust gas burner in an exhaust system downstream of an internal combustion engine, comprises supplying a predeterminable air flow to the burner, supplying a quantity of fuel to the burner, igniting the air-fuel mixture formed in the burner by supplying the air flow and the quantity of fuel, whereby a burner exhaust gas is formed, receiving a sensor signal containing information about a chemical composition of the burner exhaust gas, determining a controller output (also referred to as a control factor in the context of this invention) for controlling the composition of the burner exhaust gas using the sensor signal in order to adjust the composition of the burner exhaust gas to a predeterminable target composition, determining an adaptation value for pre-controlling the quantity of fuel based on the controller output, and adjusting the supply of the quantity of fuel to the burner using the adaptation value.

The control of the composition of the burner exhaust gas can, for example, comprise a proportional controller (P controller), and/or an integral controller (I controller), and/or a differential controller (D controller). The control of the composition of the burner exhaust gas can, for example, be implemented as a PI controller.

In at least one embodiment, the adaptation value is calculated by integrating or summing the controller output over time. This is a very simple way to collect remaining deviations and use them for adaptation.

In at least one embodiment, the adaptation value is determined as a function of one or more Several parameters from the group comprising an exhaust back pressure, a rate of change of the exhaust back pressure, a rate of change of the sensor signal, a temperature inside and/or downstream of the burner, a pressure and/or temperature of the atmosphere surrounding the burner, a mass flow of the air flow, a rate of change of the mass flow of the air flow, and a voltage of a battery supplying the burner are determined. These are parameters that can influence the chemical composition of the burner exhaust gas and/or the value or dynamics of the sensor signal, so that their consideration leads to a more correct and/or more accurate result, which increases the reliability of the method.

In at least one embodiment, the method further comprises determining a burner malfunction based on the adaptation value. In particular, the presence of a burner malfunction can be determined if the magnitude of the adaptation value exceeds a predeterminable threshold. In embodiments, the malfunction comprises one or more of the group comprising a malfunction of a fuel supply, a malfunction of an air supply, and a quality defect with regard to the supplied fuel. Faults in the burner system (e.g., injection system, air pump, valves, ignition, or similar) can result in a composition of the air-fuel mixture that permanently deviates from the actually set composition (e.g., a mixture that is too rich) and/or a composition of the burner exhaust gas that deviates from the desired composition (e.g., incomplete combustion). Therefore, in such cases, a high level of control effort or a significant adjustment of the pilot control is typically required to continue to achieve the desired exhaust gas composition. Consequently, a high value of the determined adaptation value may indicate a fault in the burner system.

In at least one embodiment, the method comprises implementing a measure depending on the detected malfunction. The measure may, in particular, comprise one or more of the following: issuing a warning message, performing a maintenance function, performing a diagnostic function, and initiating maintenance of the burner. Thus, the malfunction can be remedied, which can, for example, improve the emissions behavior of the burner and/or its efficiency.

A computing unit according to the invention, e.g. a control unit of a motor vehicle, is configured, in particular in terms of programming, to carry out a method according to the invention.

The implementation of a method according to the invention in the form of a computer program or computer program product with program code for carrying out all method steps is also advantageous, as this entails particularly low costs, especially if an executing control unit is also used for additional tasks and is therefore already present. Finally, a machine-readable storage medium is provided with a computer program stored thereon, as described above. Suitable storage media or data carriers for providing the computer program are, in particular, magnetic, optical, and electrical storage devices, such as hard disks, flash memories, EEPROMs, DVDs, and others. Downloading a program via computer networks (Internet, intranet, etc.) is also possible. Such a download can be wired or cable-based or wireless (e.g., via a WLAN network, a 3G, 4G, 5G, or 6G connection, etc.).

Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawings.

The invention is illustrated schematically in the drawing using an embodiment and is described below with reference to the drawing.

Short description of the drawings

• 1 shows schematically an exhaust system of an internal combustion engine with a burner, as can be used in embodiments of the invention.
• 2 shows a schematic embodiment of the invention using a simplified block diagram.

Embodiment(s) of the invention

In 1 An exhaust system of an internal combustion engine, as can be used in embodiments of the invention, is schematically shown and designated overall by 100. The exhaust system 100 comprises a preferred embodiment of an arrangement according to the invention with a burner 110 and a computing unit 140. The internal combustion engine is designated by 120. The burner 110 is designed to heat components 152, 154, 156 of the exhaust system 100, which serve for the exhaust gas aftertreatment 150 of an exhaust gas generated by the internal combustion engine 120. For this purpose, the burner 110 comprises a fuel metering device 112, e.g. a An injection device with pump and nozzle or similar, an air supply, which in the example shown is implemented via an air filter 102, an air pump (e.g., secondary air pump) 106, and an air valve 108, e.g., a throttle valve, as well as an ignition device 114, for example, a conventional spark plug supplied with electrical energy via an ignition coil or other power supply device. Instead of a combination of spark plug and ignition coil, a glow plug, for example, can also be used as the ignition device 114.

The components 106, 108, 112, 114 of the burner 110 are signal-conductingly connected to the computing unit 140, for example, a dedicated burner control unit, and are controlled by it. The computing unit 140 is further signal-conductingly connected to sensors, here a first sensor 138 and a second sensor 132, and receives sensor signals generated by them. The computing unit 140 can also be configured to communicate with a (further) control unit 160, which controls and monitors the operation of the internal combustion engine 120. In some embodiments, however, the burner and internal combustion engine control can also be implemented by a common computing unit, so that in such embodiments the computing units 140, 160 are designed to be integrated with one another.

The first sensor is configured to determine information regarding a chemical composition of the exhaust gas of the burner 110, in particular regarding the air/fuel ratio (lambda), and to transmit it in the form of a sensor signal to the computing unit 140. For example, the first sensor 138 may be a broadband lambda sensor or a step-wave lambda sensor. However, other sensor types that provide different or additional information may also be used if necessary.

The second sensor 132 can, for example, be configured to determine one or more parameters from the group of air mass flow, temperature and pressure and to send them to the computing unit 140 in the form of a sensor signal.

The positioning of the sensors 132, 138 is to be understood here purely as an example. The invention can also be implemented with only the first sensor 138 and also with a different positioning of the first sensor 138, as long as the first sensor 138 is arranged downstream of the burner 110.

In 2 An embodiment of the invention is shown schematically in the form of a simplified block diagram and designated overall by 200. For example, the block diagram can be interpreted as a flow chart of a corresponding embodiment of a method according to the invention. Within the scope of the method 200, a target value 1 for an exhaust gas composition (e.g. target lambda value) is compared with an actual exhaust gas composition 3 (e.g. lambda value measured by means of the first sensor 138). On the basis of the difference between the target value 1 and the actual value 3, a control value 2 (also referred to as a control factor) is determined using a controller 210 and used to control the controlled system 230 (e.g. burner 110 with the corresponding controllable components, such as air pump 106, valve 108, injection device 112, ignition device 114). The control value 2 changes a fuel quantity to be introduced, which is determined as a pilot control value or pilot control output value depending on input variables 5, such as an air quantity supplied to the burner, by an associated control or pilot control function 220. This can be, for example, a multiplicative or additive change.

The control factor 2 is also used, as already explained, to adjust or adapt the pilot control 220. For this purpose, the control factor 2 can, for example, be integrated over time (step 225) to obtain an adaptation value 4. In particular, only times are taken into account in which suitable operating conditions prevail that enable reliable adaptation 225. In particular, very dynamic operating phases (e.g., high rates of change in relation to temperature, pressure, lambda value, or similar) can be disregarded in the adaptation 225, while essentially stationary operating phases of the burner are used to determine the adaptation value 4 for the pilot control 220. Control factors 2 from correspondingly suitable operating phases are stored in a memory of the computing unit 140, if necessary together with the respective underlying additional operating parameters. This means that short-term effects that, for example, require a change in the control factor due to dynamic operating phases are not used for the adaptation 225. In particular, adaptation 225 aims to reduce the load on the control system by compensating for long-term changes (e.g., component aging). However, if the control factor were also taken into account in dynamic operating conditions, such a reduction would not be possible, as the adaptation would lead to excessively variable feedforward control.

The determined adaptation value 4 can be used in the pre-control 220 to obtain an adapted pre-control value (adapted fuel quantity). For example, the determined adaptation value 4 can be offset against the original pre-control value, in particular multiplied, to obtain an adapted pilot control value. This allows the amount of fuel supplied to the burner via the pilot control to be more accurately adjusted to the actual conditions.

On the basis of an adaptation value 4 determined in this way, a malfunction of the burner 110 can also be determined within the scope of the method 200 (in 2 symbolized by block 240). For this purpose, the adaptation value 4 (corresponds, as explained, for example, to a control factor 2 integrated over time) is compared with a predeterminable error threshold value. If the adaptation value 4 exceeds the threshold value, the presence of a malfunction is determined. In particular, depending on the other operating parameters (e.g., lambda value, temperature, pressure, etc.), a distinction can also be made between different malfunctions. If a malfunction is determined to be present, an appropriate measure can be taken, for example, issuing a warning message to alert a burner user to the malfunction. Adjusting the control of the burner 110 and/or the internal combustion engine can also be used as such a measure, for example, to reduce the raw emissions of the burner 110 and/or the internal combustion engine or to otherwise heat the exhaust system 100 to the desired operating temperature.

It should be emphasized here that the method 200 can also be used with other suitable exhaust systems and is not limited to the specific design of the 1 exhaust system 100 shown. This is shown merely to illustrate some aspects of the invention.

QUOTES CONTAINED IN THE DESCRIPTION

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

• DE 41 32 814 A1 [0004]
• DE 195 04 208 A1 [0004]

Claims (12)

A method (200) for operating a burner (110), in particular an exhaust gas burner in an exhaust system (100) downstream of an internal combustion engine (120), the method (200) comprising: supplying a predeterminable air flow (106, 108) to the burner (110), supplying a quantity of fuel (112) to the burner (110), igniting (114) the air-fuel mixture formed in the burner (110) by supplying the air flow and the quantity of fuel, thereby forming a burner exhaust gas, receiving a sensor signal (3) containing information about a chemical composition of the burner exhaust gas, determining a controller output (2) for controlling (210) the chemical composition of the burner exhaust gas using the sensor signal in order to adjust the composition of the burner exhaust gas to a predeterminable target composition (1), determining an adaptation value (4) for a pre-control (220) of the fuel quantity (112) based on the controller output (2), and adjusting the supply of the fuel quantity (112) to the burner (110) using the adaptation value (4). Procedure (200) according to Claim 1 , wherein the adaptation value (4) is determined as a function of one or more parameters from the group comprising an exhaust gas back pressure, a rate of change of the exhaust gas back pressure, a rate of change of the sensor signal (3), a temperature inside and/or downstream of the burner (110), a pressure and/or a temperature of the atmosphere surrounding the burner (110), a mass flow of the air flow (106, 108), a rate of change of the mass flow of the air flow and a voltage of a battery supplying the burner (110). Procedure (200) according to Claim 1 or 2 comprising determining a malfunction (240) of the burner (110) based on the adaptation value (4). Procedure (200) according to Claim 3 , wherein the presence of a malfunction (240) of the burner (110) is determined if the amount of the adaptation value (4) exceeds a predeterminable threshold value. Procedure (200) according to Claim 3 or 4 wherein the malfunction (240) comprises one or more of the group comprising a malfunction of a fuel supply (112), a malfunction of an air supply (106, 108) and a quality defect with respect to the supplied fuel. Method (200) according to one of the Claims 3 until 5 , comprising carrying out a measure depending on the detected malfunction (240). Procedure (200) according to Claim 6 , wherein the measure comprises one or more of the group consisting of issuing a warning message, performing a maintenance function, performing a diagnostic function and initiating maintenance of the burner. Method (200) according to one of the preceding claims, wherein determining the adaptation value (4) for the pre-control (220) of the fuel quantity (112) based on the controller output (2) comprises integrating the controller output (2). Computing unit (140) configured to perform all method steps of a method (200) according to one of the preceding claims. Arrangement with a burner (110), in particular an exhaust gas burner in an exhaust system (100) downstream of an internal combustion engine (120), and a computing unit according to Claim 9 . Computer program which causes a computing unit (140) to carry out all method steps of a method (200) according to one of the Claims 1 until 8 to perform when executed on the processing unit. Machine-readable storage medium with a computer program stored thereon in accordance with Claim 11 .

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