DE102018005111A1 - Method for checking a particle filter of an internal combustion engine, in particular for a motor vehicle - Google Patents

Abstract

The invention relates to a method for checking a particle filter (18) of an internal combustion engine (10) having an exhaust gas system (16), the particle filter (18) arranged in the exhaust system (16) and at least one exhaust gas turbocharger (20), in which the exhaust gas turbocharger (20 ) a turbine (22) arranged in the exhaust gas system (16) through which exhaust gas from the internal combustion engine (10) can flow, with a turbine wheel (24), a bypass line (38) via which the turbine wheel (22) is connected by at least one Part of the exhaust gas is to be bypassed, and has a bypass valve (40) which can be moved into a plurality of different positions and by means of which a quantity of the exhaust gas flowing through the bypass line (38) can be set, with the steps: determining the position of the bypass valve (40); and checking the particle filter (18) as a function of the determined position of the bypass valve (40).

Description

The invention relates to a method for checking a particle filter of an internal combustion engine, in particular for a motor vehicle, according to the preamble of patent claim 1.

Such a method for checking a particle filter of an internal combustion engine having an exhaust system, the particle filter arranged in the exhaust system and at least one exhaust gas turbocharger, in particular for a motor vehicle, is already the example DE 10 2008 059 697 A1 as known. In the method, the exhaust gas turbocharger has a turbine with a turbine wheel arranged in the exhaust gas system through which exhaust gas of the internal combustion engine can flow, upstream of the particle filter. In addition, the exhaust gas turbocharger has a bypass line, via which the turbine wheel can be bypassed by at least part of the exhaust gas. This means that the exhaust gas flowing through the bypass line bypasses the turbine wheel and thus does not drive the turbine wheel. In addition, the exhaust gas turbocharger has a bypass valve which can be moved into a plurality of different positions and which is also referred to as a waste gate or waste gate valve. A quantity of the exhaust gas flowing through the bypass line can be set by means of the valve, in particular depending on the position of the bypass valve.

Furthermore, the DE 10 2015 215 373 A1 a method for exhaust gas aftertreatment of a chargeable, spark-ignited internal combustion engine.

The object of the present invention is to further develop a method of the type mentioned at the outset in such a way that the particle filter can be checked in a particularly simple manner.

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

In order to further develop a method of the type specified in the preamble of patent claim 1 in such a way that the particle filter, for example a diesel particle filter or gasoline particle filter, can be checked, that is to say diagnosed, in a particularly simple manner, the invention provides that, in particular by means of an electronic computing device, the particular, in particular current position of the bypass valve is determined. In addition, the particle filter is checked depending on the determined position of the bypass valve.

The determined position is used, for example, as an actual position, which is compared with at least one target position. The particle filter is checked, for example, depending on the comparison.

The desired position is called up, for example, from a map stored in a memory device of the electronic computing device. It has proven to be particularly advantageous if the setpoint position is called up from the characteristic diagram as a function of a current operating point, in particular as a function of a current load.

The invention is based in particular on the following findings: When using a particle filter, for example for a gasoline or gasoline engine or for a diesel engine, the particle filter should be able to be diagnosed, that is to say checked, depending on the exhaust gas legislation. Checking the particle filter includes, for example, checking whether the particle filter is installed or not, that is to say is arranged in the exhaust system or not. Furthermore, the check can include monitoring the filtration efficiency of the particle filter and / or monitoring a degree of loading of the particle filter. The degree of loading is also referred to as loading and characterizes an amount of particles, in particular soot particles, which have been taken up in the particle filter and which have been filtered out of the exhaust gas by means of the particle filter and have been deposited in the particle filter. The degree of loading is relevant to assess whether particle storage can still be made possible. On the one hand, the filtration efficiency can drop at high loading levels. On the other hand, a greatly increased exhaust gas back pressure can lead to component damage.

The particle filter, in particular its degree of loading, is usually determined by means of a delta pressure sensor, which is also referred to as a differential pressure sensor and which can determine a pressure difference, also known as a pressure delta, via a pressure measurement upstream and downstream of the particle filter. The degree of loading can be determined from the pressure delta. If the pressure delta falls below a predeterminable threshold, for example, it can be concluded that the particle filter is not installed, is damaged or has been removed, since even an unloaded particle filter causes a pressure change or a pressure delta that is greater than zero. It is desirable to have a further and / or alternative diagnostic option for which the delta pressure sensor is not required. Such a further or alternative diagnostic option is advantageous if, for example, one of the delta pressure sensor provided and the signal characterizing by means of the delta pressure sensor characterizing at least temporarily cannot be evaluated, the delta pressure sensor fails or such a delta pressure sensor is to be dispensed with.

The method according to the invention represents such an alternative diagnostic option since the position of the bypass valve, in particular a change in the position of the bypass valve, is used as a measure of the changing exhaust gas back pressure or for a change in the exhaust gas back pressure, such a change in the exhaust gas back pressure usually being effected by the particle filter or caused by its loading and / or its damage. In other words, the invention is based on the knowledge that the particle filter influences the exhaust gas back pressure, so that, for example, there is a change in the exhaust gas back pressure if the particle filter is initially installed and is removed from the exhaust system and / or is damaged or if the loading of the Particulate filter increases. The exhaust gas back pressure or its change leads to a change in the position of the bypass valve, so that the particle filter can be diagnosed on the basis of the position of the bypass valve, in particular on the basis of a change in the position of the bypass valve.

By increasing the pressure after the turbine ( p4 ) due to the particle filter or its loading, the pressure drop from the pressure decreases p3 (in front of the turbine) to the pressure p4 , As a result, this must also be called a waste gate ( WG ) designated bypass valve depending on the change in the pressure gradient or in dependence on a change in the pressure p4 be closed further to keep the speed of the exhaust gas turbocharger constant so that, for example, the intake manifold pressure does not drop. Closing the waste gate in turn increases the exhaust gas back pressure p3 , Thereupon the gas exchange work increases because the exhaust gas has to be pushed out of the combustion chamber against a higher pressure. The result would be a lower effective medium pressure and thus a lower effective torque. The load detection of the engine control system compensates for this with a higher intake manifold pressure. This causes a higher high pressure work, which compensates for the higher charge exchange work. In total, the same effective mean pressure can be set despite a higher exhaust gas back pressure. The higher intake manifold pressure can be achieved by closing the waste gate even more. In the event of a drop in pressure p4 For example, what results from an expansion of the particle filter, the effects described above are reversed, and the waste gate has to be opened further and the required intake manifold pressure drops.

In summary, the change in the position of the bypass valve can provide information about how heavily the particle filter is loaded or whether the particle filter is installed at all, that is to say is arranged in the exhaust system. For this purpose, the position of the bypass valve is compared with a reference position in the form of the target position, which can be generated, for example, at the beginning of the vehicle life with a new, unloaded particle filter. From the deviation of the actual position from the reference position, the load can be calculated back, or a removed or damaged particle filter can be diagnosed.

Another object of the invention is to use the above-described change in the intake manifold pressure by the particle filter or its loading as a diagnostic option, in particular for a delta pressure calculation. The reasons for a possible change in intake manifold pressure have already been described above. For example, a pressure currently prevailing in the intake manifold is determined, in particular measured, and compared with a reference pressure. The reference pressure is, for example, a pressure prevailing in the intake manifold when the new particle filter is unloaded. The degree of loading of the particle filter can be inferred from the deviation of the measured pressure from the reference pressure or a diagnosis can be made as to whether the particle filter is damaged or not installed at all.

Since the particle filter causes a significant back pressure, especially with high exhaust gas volume flows, the pressure change determination via the position of the waste gate or via the change in the intake manifold pressure is particularly useful in high load ranges at higher speeds. Load ranges in which no charging and therefore no waste gate control is required cannot be used for the diagnosis.

• - bei Entfall des Deltadrucksensors deutliche Kosteneinsparung
• - Anwendung als Ersatzdiagnose möglich
• - Im Vergleich zur Druckmessung über Deltadrucksensor ist ein Diagnoseergebnis bei hohen Abgasvolumenströmen und Beladungsraten möglich.
• - Im Vergleich zur Druckmessung über Deltadrucksensor kann je nach Zyklus ein Diagnoseergebnis schneller ermittelt werden, da beispielsweise auch ein Warten auf ein Taupunktende am Deltadrucksensor verzichtet werden kann.

The type of diagnosis described should take place under similar environmental conditions, which were also used for the reference determination, since the height above sea level and the intake air temperature can influence the position of the bypass valve and the intake manifold pressure. The reference values can be determined in different or several engine operating points in order to increase the possibility of diagnosis. In particular, the following advantages can be realized by means of the method according to the invention:

• - Significant cost savings if the delta pressure sensor is omitted
• - Can be used as a replacement diagnosis
• - In comparison to pressure measurement via delta pressure sensor, a diagnostic result is included high exhaust gas volume flows and loading rates possible.
• - In comparison to the pressure measurement using the delta pressure sensor, depending on the cycle, a diagnostic result can be determined more quickly, since, for example, there is also no need to wait for the end of the dew point at the delta pressure sensor.

Overall, it can be seen that a delta pressure detection by particle filter can be detected by changing the waste gate position and / or changing the intake manifold pressure, so that, for example, a removal detection of the particle filter, a determination of the degree of loading and a determination of the aging of the particle filter can be realized.

Further advantages, features and details of the invention emerge from the following description of a preferred exemplary embodiment and from the drawing. 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 combination specified in each case, but also in other combinations or on their own, without the frame to leave the invention.

In the single figure, the drawing shows a schematic representation of an internal combustion engine which is designed to carry out a method according to the invention.

The only FIG. Shows a schematic illustration of an internal combustion engine 10 of a motor vehicle, which can preferably be designed as a motor vehicle and thereby as a passenger car. The internal combustion engine 10 has a motor housing 12 which has at least one combustion chamber, for example a cylinder 14 forms. During fired operation of the internal combustion engine 10 run in the combustion chamber 14 Combustion processes from which exhaust gas from the internal combustion engine 10 results. The internal combustion engine 10 has an exhaust tract through which the exhaust gas can flow, which also serves as an exhaust system 16 referred to as. The exhaust system 16 has a particle filter through which the exhaust gas can flow 18 by means of which any particles contained in the exhaust gas, in particular soot particles, can be at least partially filtered out of the exhaust gas. The internal combustion engine 10 is designed as a supercharged internal combustion engine and for this purpose comprises at least or exactly one exhaust gas turbocharger 20 which is a turbine 22 with a turbine wheel 24 having. The turbine 22 and especially the turbine wheel 24 are in the exhaust system 16 arranged so that the turbine 22 can be flowed through by at least part of the exhaust gas. The the turbine 22 Part of the exhaust gas flowing through the turbine wheel 24 drive.

The internal combustion engine 10 also has an intake tract also referred to as an intake tract 26 on which air can flow. By means of the intake tract 26 becomes the intake tract 26 Air flowing through and in particular into the combustion chamber 14 directed. It is in the intake tract 26 an air filter 28 for filtering the intake tract 26 arranged flowing air. The exhaust gas turbocharger 20 has one in the intake tract 26 arranged compressor 30 on which is a compressor wheel 32 includes. By means of the compressor wheel 32 can the intake tract 26 flowing air can be compressed. For this the compressor wheel 32 from the turbine wheel 24 driven. The intake tract 26 comprises at least one conduit element through which the air can flow 34 , which is also called a suction pipe. During the fired operation, a pressure prevails in the intake manifold, which is also referred to as intake manifold pressure.

It can be seen from the figure that the particle filter 18 in the flow direction of the exhaust system 16 exhaust gas flowing downstream of the turbine 22 and especially downstream of the turbine wheel 24 is arranged.

The exhaust gas turbocharger 20 has a bypass facility 36 on which is at least or exactly a bypass line 38 includes. The bypass line 38 is at a junction A and at an introduction point e fluid with the exhaust system 16 connected. At the junction A can be at least part of the exhaust system 16 flowing exhaust gas from the exhaust system 16 branched off and into the bypass line 38 be initiated. The bypass line 38 Exhaust gas flowing through bypasses the turbine wheel 24 so that the turbine wheel 24 not by which the bypass line 38 flowing exhaust gas driven, but from which the bypass line 38 flowing exhaust gas is bypassed. At the discharge point e can the bypass 38 Exhaust gas flowing through the bypass line 38 flow out and back into the exhaust system 16 flow. The junction A is upstream of the turbine wheel 24 arranged, the discharge point e downstream of the turbine wheel 24 and upstream of the particle filter 18 is arranged. Upstream of the turbine wheel 24 there is also one p3 designated first pressure of the exhaust gas, the first pressure also being referred to as the first exhaust gas pressure. Downstream of the turbine wheel 24 and upstream of the particle filter 18 there is a second pressure of the exhaust gas in the exhaust system 16 , the second pressure is also referred to as the second exhaust gas pressure. Because the exhaust gas by means of the turbine wheel 24 is relaxed, the first exhaust gas pressure is usually lower than the second exhaust gas pressure, which also with p4 referred to as.

The bypass facility 36 further includes a bypass valve, also referred to as a waste gate or waste gate valve 40 which, for example, to the bypass line 38 is arranged. By means of the bypass valve 40 can the bypass line 38 flowing amount of the exhaust gas can be set. As a result, the boost pressure of the exhaust gas turbocharger 20 set, in particular regulated.

The bypass valve 40 can, in particular by means of an actuator, not shown in the figure, be moved into several different positions.

For example, each of the positions of the bypass valve corresponds 40 with exactly one bypass line 38 flowing amount of the exhaust gas.

Around the particle filter 18 in a particularly simple manner and, for example, without being able to check and, in particular, to be able to diagnose the use of a differential pressure sensor, it is within the scope of a method for checking the particle filter 18 provided that the current position of the bypass valve 40 is determined. In addition, the particle filter 18 depending on the determined position of the bypass valve 40 checked. For this purpose, for example, the determined position as the actual position is compared with a target position, in particular as a function of a current operating point, in particular as a function of a current load, of the internal combustion engine 10 , Alternatively or additionally, it is conceivable that, in particular by means of a pressure sensor, at least one pressure prevailing in the intake manifold and also referred to as intake manifold pressure is determined, in particular measured. It is conceivable that the particle filter 18 is checked as a function of the determined, in particular measured, intake manifold pressure. For this purpose, for example, the measured intake manifold pressure is compared with a target pressure or reference pressure, in particular as a function of the current operating point or the current load of the internal combustion engine 10 ,

In particular, as part of the checking of the particle filter 18 whose degree of loading can be determined. Alternatively or additionally, damage to the particle filter can occur 18 can be determined and / or a removal detection can be carried out, in the course of which it is checked whether the particle filter 18 actually in the exhaust system 16 arranged or not installed.

LIST OF REFERENCE NUMBERS

10

Internal combustion engine

12

motor housing

14

combustion chamber

16

exhaust system

18

particulate Filter

20

turbocharger

22

turbine

24

turbine

26

intake system

28

air filter

30

compressor

32

compressor

34

line element

36

bypass means

38

bypass line

40

bypass valve

A

branching point

e

inlet point

QUOTES INCLUDE IN THE DESCRIPTION

This list of documents listed by the applicant has been generated automatically and is only included for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 102008059697 A1 [0002]
• DE 102015215373 A1 [0003]

Claims (4)

Method for checking a particle filter (18) of an internal combustion engine (10) having an exhaust gas system (16), the particle filter (18) arranged in the exhaust system (16) and at least one exhaust gas turbocharger (20), in which the exhaust gas turbocharger (20) is one in the Exhaust system (16) through which exhaust gas from the internal combustion engine (10) can flow and upstream of the particle filter (18) has a turbine (22) with a turbine wheel (24), a bypass line (38) via which the turbine wheel (22) is connected to at least part of the exhaust gas is bypassed, and has a bypass valve (40) which can be moved into several different positions and by means of which an amount of the exhaust gas flowing through the bypass line (38) can be set, characterized by the steps: - determining the position of the bypass valve (40); and - checking the particle filter (18) as a function of the determined position of the bypass valve (40). Procedure according to Claim 1 , characterized in that the determined position is compared as an actual position with at least one target position, the particle filter (18) being checked as a function of the comparison. Procedure according to Claim 2 , characterized in that the target position is called up from a map stored in a memory device of an electronic computing device. Procedure according to Claim 3 , characterized in that the setpoint position is called up as a function of a current operating point, in particular as a function of a current load, of the internal combustion engine (10) from the characteristic diagram.

Images