DE102022214199A1 - Method for operating a system for supplying air to a burner - Google Patents

Abstract

Method for operating a system (40) for supplying air to a burner (43), in particular for conditioning a catalyst (37), which is designed in particular as a three-way catalyst, wherein a pump (58) conveys air between an air inlet (46) in the system (40) and the burner (43), characterized in that a defect in the system (40) is determined by means of two different air mass flows.

Description

State of the art

It is known that the use of three-way catalysts is necessary to achieve emission limits. Such emission limits are set, for example, by the EU emissions standard EU6. These three-way catalysts enable the conversion of the relevant gaseous pollutants, such as nitrogen oxide NOx, hydrocarbons HC and carbon monoxide CO into harmless products such as nitrogen N2, water H2O and carbon dioxide CO2. In order for the catalytic reactions required for this to take place, the temperature in the catalyst, the so-called light-off temperature, must exceed typically 300°C to 400°C. As soon as this temperature is reached, the catalyst converts the relevant pollutants almost completely and a light going out can signal that the catalyst is ready for operation (light-off). In order to achieve this state as quickly as possible, it has already been proposed to use so-called internal engine catalyst heating measures. These internal catalyst heating measures change the efficiency of the internal combustion engine (particularly the gasoline engine) through so-called late ignition angles in such a way that the exhaust gas is relatively warm, thus increasing the exhaust gas temperature and the so-called enthalpy input into the catalyst. At the same time, stable combustion is ensured through intelligent injection strategies (e.g. multiple injections). With the test cycles that have been valid to date (NEDC, FDP 75), which all begin with an extended idling phase, a rapid light-off temperature with low emissions could be ensured.

In addition to these internal engine catalyst heating measures, external engine catalyst heating measures have also been investigated in the past. These include, for example, electrically heated catalysts, but also so-called exhaust gas burners, such as those described in the published documents DE 41 32 814 A1 and DE 195 04 208 A1 are known.

In connection with the exhaust gas standards that have been in force up to now, it was still possible to comply with these standards simply by heating the catalytic converter inside the engine, despite the increasingly strict requirements in the past. For this reason, the external catalytic converter heating measures mentioned above, such as the electrically heated catalytic converter or the exhaust gas burner, or burner for short, have not yet been able to establish themselves on the market. With the introduction of the determination of emissions that are determined under realistic driving conditions (real driving emissions, RDE), driving situations in which the conversion of various exhaust gas components by the three-way catalytic converters mentioned above is not possible solely by heating the catalytic converter inside the engine are becoming more important. These so-called RDE boundary conditions include, for example, the so-called urban spontaneous cold start of a motor vehicle, which takes place with a high engine load without a prior idling phase. Such real driving conditions push the familiar internal catalyst heating to its limits, especially when further reduced emission limits are to be expected at the same time, which must be complied with. This is expected for the EU emissions standard EU7, for example. In connection with these requirements, a so-called exhaust gas burner turns out to be an extremely effective measure. Using such an exhaust gas burner, it is possible to bring a three-way catalyst extremely quickly to the aforementioned light-off temperature, at which the pollutants are converted very early.

Embodiments of the invention

According to a first aspect of the invention, a method is provided for operating a system for supplying air to a burner, in particular for conditioning a catalyst, which is designed in particular as a three-way catalyst. A pump conveys air between an air inlet in the system and the burner. A defect, in particular a leak or a defective pump, in the system is determined using two different air mass flows, which are based in particular on different models.

According to a further aspect of the method, it is provided that one air mass flow, for example referred to as the actual mass flow, is determined using a signal from a sensor element - in particular via a first determination path - and the other air mass flow is determined using a characteristic curve of the pump. In this case, it is particularly provided that the signal is processed in a first air mass flow model. This has the advantage that if the air mass flows are the same in terms of amount, it can be concluded that the system is functioning and error-free.

According to a further aspect of the method, it is provided that in the second determination method, the characteristic curve of the pump for determining the other air mass flow is influenced by a speed of the pump and a counter pressure of the pump. In particular, it can be provided that the other air mass flow is additionally is determined depending on the temperature of the air mass flow.

According to a further aspect of the method, an air mass flow difference is determined from the two air mass flows determined using different determination methods, which is then compared with a threshold value. By comparing with a threshold value, significant air mass flow differences can advantageously be distinguished from insignificant ones, and a leak or a defective pump can thus be concluded if a deviation exceeds the threshold value.

According to a further aspect of the method, it is provided that one air mass flow is smaller than the other air mass flow and therefore a leak in the section of the system between the sensor element and the pump or a defective sensor element is concluded.

According to a further aspect of the method, it is provided that one air mass flow is greater than the other air mass flow and therefore a defective pump is concluded.

In addition, a computer program is provided which is designed to carry out all the steps of one of the methods or which is programmed to carry out a method when executed on a computer.

In addition, a machine-readable storage medium is provided on which the computer program is stored or on which the computer program is stored for use in a method.

Furthermore, a control device is provided which is designed to carry out all steps of one of the methods or which is programmed for use in a method.

• 1 eine schematische Ansicht der Anlage zur Zuführung von Luft zu einem Brenner,
• 2 eine schematische Darstellung des erfindungsgemäßen Verfahrens.

The invention is explained in more detail below with reference to the two figures shown. They show:

• 1 a schematic view of the system for supplying air to a burner,
• 2 a schematic representation of the method according to the invention.

In 1 a device 10 is shown which is in particular a motor vehicle. This device 10 has an internal combustion engine 13 which is supplied with air via an intake device 16. This intake device 16 has an air inlet 19. In the air supply to the internal combustion engine 13 there is also a sensor element 22 and then a valve 25 which is typically designed as a so-called throttle valve. The air inlet 19 typically leads into a so-called box 28 (air filter box) so that the admitted air first flows through the air inlet 19 and then flows through an air filter not described in more detail here. The intake device 16 has an intake pipe 31 in which the aforementioned sensor element 22 is arranged. The valve 25 is also arranged in this intake pipe 31. The exhaust gases or combustion gases generated by the internal combustion engine 13 are introduced into an exhaust system 34. One part of this exhaust system is, for example, a catalyst 37. After passing through the catalyst 37, the converted exhaust gases are released into the environment (arrow).

In 1 the system 40 for supplying air to a burner 43 is also shown. This system 40 also has an air inlet 46, which represents an entrance to a box 49. An air filter can also be arranged in this box 49. The boxes 28, 49 can also be designed as one box, as is symbolically shown by the dashed rectangle around both boxes 28, 49 without any further designation. Accordingly, such a combined box can also have only one air inlet, which combines the two air inlets 19, 46. In addition, such a box can also have a single air filter, which represents the two air filters mentioned above. The air passing through the air inlet 46 into the box 49 then enters an intake pipe 52, in which a sensor element 55 is also arranged. The sensor element 55 can, for example, be designed as a sensor element for detecting pressure. If this sensor element 55 is, for example, part of a so-called hot film measuring probe, this can be used as a whole to determine the pressure, temperature and humidity of the air. The incoming air then passes through a pump 58 and is fed by this pump 58 to a valve 61 (shut-off valve). This valve 61 serves - as the name suggests - to shut off the air supply to the burner 43. In a section of the system 40 between the pump 58 and the valve 61 there is a further sensor element 64, which can be designed, for example, as a sensor element for detecting pressure or as a sensor element for detecting temperature. The sensor element 64 can be designed, for example, as a sensor element for detecting pressure. The sensor element 22 can be designed like the sensor element 55. A further sensor element 67 is arranged between the valve 61 and the burner 43, which can, for example, measure a temperature and/or a pressure of the air flowing past. can detect. In the flow direction after the burner 43, a mechanical component is shown, which is, for example, a screw connection with flanges. The device 10 shown here also has a control unit 70, which is connected to individual components of this device 10 via signal lines, which are not described in more detail here. These signal lines are used for communication between the individual components and the control unit 70. This control unit has a machine-readable storage medium 73, on which, for example, a computer program 76 is stored.

The method explained below is intended for the purpose of detecting a leak or a so-called hose drop, i.e. the loosening or falling off of an air-carrying hose of the system, i.e. in the air supply upstream of the pump 58 to the burner 43, or the detection of a defective pump 58. It is intended that two different, in particular differently modeled air mass flows are determined, based on which a defect in the system 40 is determined. Both air mass flows are determined in different ways. For example, one air mass flow is determined in step S1 by means of a signal s55 of the sensor element 55. This sensor element 55 can be designed, for example, as a hot-film mass meter. As such, the sensor element 55 can be arranged in a sensor device that has several different sensor elements or probes. For example, this can be a product from the applicant's company, the BOSCH HFM8-pTH. This product can be used to determine a pressure p, a temperature T and air humidity H. With the help of this sensor element 55, the signal s55 is processed using a first determination path in a first model (first air mass flow model) and an air mass flow ms55 is determined. This air mass flow can be referred to as the actual mass flow, for example. The other air mass flow ms58 is determined in step S2 using the characteristic curve k58 of the pump 58 and thus with a second air mass flow model. Assuming high quality of the two air mass flow models and a functioning, fault-free system 40, the two determined air mass flows ms55, ms58 should be the same.

It is intended that the characteristic curve k58 of the pump 58 used for the second air mass flow model to determine the other air mass flow ms58 is influenced by a speed n58 of the pump 58 and a back pressure p58 of the pump 58. A back pressure p58 of the pump 58 can be determined, for example, by the sensor element 64 and a speed n58 of the pump 58 can be determined by a speed sensor element arranged on a pump shaft (not shown here), by which the speed n58 of the pump 58 is determined. In addition, the characteristic curve k58 of the pump 58 to determine the other air mass flow ms58 can be determined as a function of a temperature T58.

If an air mass flow difference Dms is now determined in step S3 from the two air mass flows ms55, ms58 determined using different determination methods, which is then compared with a threshold value SWms, a decision can be made based on the air mass flow difference Dms and the respective category as to whether there is a defect in the pump 58 or a leak in the system 40. If the air mass flow difference Dms is smaller than the threshold value SWms, it is decided (step S5), for example, that there is no defect in the pump 58 and no leak. If the air mass flow difference Dms is larger than the threshold value SWms, it is decided (step S5), for example, that there is a defect in the pump 58 or a leak.

If one air mass flow ms55 is smaller than the other air mass flow ms58, it is therefore concluded that there is a leak in the section of the system 40 between the sensor element 55 and the pump 58 or that the sensor element 55 is defective (step S5).

If one air mass flow ms55 is greater than the other air mass flow ms58, it is therefore concluded that pump 58 is defective.

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. 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

• DE 4132814 A1 [0002]
• DE 19504208 A1 [0002]

Claims (9)

Method for operating a system (40) for supplying air to a burner (43), in particular for conditioning a catalyst (37), which is designed in particular as a three-way catalyst, wherein a pump (58) conveys air between an air inlet (46) in the system (40) and the burner (43), characterized in that a defect, in particular a leak or a defective pump, in the system (40) is determined by means of two different air mass flows (ms55, ms58), which are based in particular on different models. Procedure according to Claim 1 , characterized in that one air mass flow (ms55) is determined by means of a signal (s55) of a sensor element (55) and the other air mass flow (ms58) is determined by means of a characteristic curve (k58) of the pump (58). Procedure according to Claim 2 , characterized in that the characteristic curve (k58) of the pump (58) for determining the other air mass flow (ms58) is influenced by a rotational speed (n58) of the pump (58) and a back pressure (p58) of the pump (58). Method according to one of the preceding claims, characterized in that an air mass flow difference (Dms) is determined from the two air mass flows (ms55, ms58) determined on different determination paths, which air mass flow difference is compared with a threshold value (SWms). Method according to one of the preceding claims, characterized in that one air mass flow (ms55) is smaller than the other air mass flow (ms58) and therefore a leak in the section of the system (40) between the sensor element (55) and the pump (58) or a defective sensor element (55) is concluded. Procedure according to Claim 4 , characterized in that one air mass flow (ms55) is greater than the other air mass flow (ms58) and therefore a defective pump (58) is concluded. Computer program (76) which is designed to carry out all the steps of one of the methods according to one of the Claims 1 until 6 or that it is programmed in such a way that it carries out a method according to any of the Claims 1 until 6 when run on a computer. Machine-readable storage medium (73) on which the computer program (76) according to Claim 7 or that the computer program (76) is stored on it according to Claim 7 for use in a procedure of Claims 1 until 6 is saved. Control device (70) which is designed to carry out all the steps of one of the methods according to one of the Claims 1 until 6 or that it is intended for use in a procedure under any of the Claims 1 until 6 is programmed.

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