DE102018133041A1 - Exhaust system with a particle filter and a particle measuring device for an internal combustion engine and motor vehicle internal combustion engine with an exhaust system - Google Patents

Abstract

Exhaust system of an internal combustion engine (9) for a motor vehicle with a particle filter (12), the exhaust system for guiding exhaust gas from the internal combustion engine (9) to the environment in an exhaust gas flow direction and having an exhaust gas measurement sensor (1) for measuring exhaust gas properties, wherein this exhaust gas measurement sensor (1) for measuring the exhaust gas properties is flowed through by a carrier gas and has a carrier gas supply (6) and a sample gas outlet (7), the sample gas outlet (7) being set up for discharging at least the carrier gas from the exhaust gas measurement sensor (1), thereby characterized in that the exhaust gas measuring sensor (1), in relation to the exhaust gas flow direction, is arranged in the exhaust line such that the measuring gas outlet (7) is arranged upstream of the particle filter (2) and that the carrier gas is a non-reactive gas.

Description

The invention relates to an exhaust system with a particle filter for an internal combustion engine and a motor vehicle internal combustion engine with such an exhaust system. From the DE 10 2014 015 634 A1 a particle measuring device and an exhaust line according to the preamble of claim 1 is known.

The invention is described below in connection with a known exhaust line of an internal combustion engine of a motor vehicle; this should not be understood as a restriction of the invention to such an application. Such an internal combustion engine burns fuel with ambient air in at least one combustion chamber and converts the energy released in the process into mechanical drive power for driving the motor vehicle. The exhaust gases released during the combustion of the fuel can be measured during a test cycle (NEDC, WLTP, etc.) or during real operation (RDE, etc.) of the internal combustion engine, in particular the number and mass of the small and smallest contained in the exhaust gas of the internal combustion engine Solid particles, in particular the soot particles, are of interest. An exhaust gas measuring sensor is known from the prior art for measuring this exhaust gas, which sensor is flushed with compressed air or ambient air due to its measuring principle. This air supplied to the exhaust gas measuring sensor is ionized for measurement and then combined with the particulate-containing exhaust gas from the internal combustion engine, which is led through the sensor for measurement, and the abovementioned exhaust gas properties (particle mass concentration, particle number concentration) are determined.

To filter the exhaust gas, a so-called particle filter is arranged in the exhaust line, which can be cleaned alternately by burning the filtered-out and stored particles in the particle filter. The burning off of the particles in the particle filter is promoted by the supply of fresh air. This cleaning of the particle filter on the one hand reduces the exhaust gas back pressure, since the exhaust gas from the internal combustion engine flows more easily through the cleaned filter and this can improve the efficiency of the internal combustion engine, on the other hand the filtration effect of the cleaned particle filter temporarily deteriorates and the completely cleaned particle filter can initially have fewer particles filter out of the exhaust gas. It is therefore a general goal to operate a particle filter within narrow limits between good filtering efficiency (filtration efficiency) and low exhaust gas back pressure, in particular to minimize disturbances to the loading (particles captured in the particle filter) of the particle filter. Another or further aim of the invention can be to obtain the best possible understanding of the processes for soot build-up and breakdown in the particle filter and to provide a model that is as accurate as possible. It is also advantageous for controlling or examining the internal combustion engine to measure exhaust gases from it as "untreated" as possible. The untreated exhaust gas allows conclusions to be drawn about the combustion taking place in the internal combustion engine.

Overall, the problem arises that when an exhaust gas measurement sensor through which carrier gas flows is arranged upstream of the particle filter, the loading of the particle filter can be influenced by the carrier gas introduced into the exhaust gas line, and that when the exhaust gas measurement sensor is arranged downstream of the particle filter, only that which has already been filtered and thus treated is left Exhaust gas can be measured. In this context, upstream of the particle filter is to be understood in particular in such a way that the exhaust gas supplied to the exhaust gas measurement sensor comes from the exhaust line upstream of the particle filter and is therefore not yet cleaned by the particle filter.

It is an object of the invention to provide an exhaust line of an internal combustion engine with which the internal combustion engine can be operated efficiently. This object is achieved by an exhaust system according to patent claim 1 and by a motor vehicle internal combustion engine according to patent claim 9; preferred developments of the invention are the subject of the dependent patent claims.

In the case of a conventional measurement, purging the exhaust gas measuring sensor with oxygen-containing gas, the additional oxygen introduced by this purging would have to be taken into account for the soot build-up or breakdown in the particle filter in the form of an adaptation of the model. In the case of the proposed invention, a model adaptation can be dispensed with, since the non-reactive gas (inert gas or exhaust gas) used for the purging does not take part in the reaction, in particular in the soot build-up or breakdown in the particle filter. but also in real engine operation by the invention an advantage over conventional systems.

In the sense of the invention, an internal combustion engine is to be understood as a thermal engine for burning fuel, preferably gasoline or diesel fuel, with ambient air in at least one combustion chamber and for delivering mechanical drive power which is obtained from this combustion of the fuel. Such an internal combustion engine is preferably a so-called reciprocating piston engine, which is preferably after the two-stroke or preferably after is operable according to the four-stroke principle, and more preferably this reciprocating piston engine can be operated according to the diesel or, preferably, according to the petrol principle. When the fuel is burned in the at least one combustion chamber, exhaust gases are produced which are discharged from the combustion chamber into the environment by means of an exhaust gas line. Devices for noise reduction and exhaust gas purification are preferably provided in this exhaust line. Such an exhaust system can be colloquially referred to as an exhaust or exhaust system.

An object of the invention is to measure the most untreated exhaust gas from the internal combustion engine with an exhaust gas measurement sensor through which carrier gas flows. A further object of the invention is to introduce no additional oxygen into the exhaust system upstream of a particle filter arranged in the exhaust line, since this additional oxygen, depending on the temperature in the exhaust line, can lead to the undesired burning off of the load of the particle filter, in particular of soot particles . In particular, burning off such particles from the particle filter due to the carrier gas flowing through the exhaust gas measurement sensor can lead to a falsification of the measurement results or to a reduction in the loading of the particle filter and thus to a temporary deterioration in the filtration efficiency of the particle filter. In other words, the use of the measurement technology, in particular the exhaust gas measurement sensor, can lead to a state in the particle filter that is different than without the use of this measurement technology, and the measurement technology can thus influence the results to be measured. Modeling based on results influenced in this way allows only an inaccurate calculation of the loading of the particle filter, it is therefore preferred to design the exhaust system so that the results to be measured are not influenced by the arrangement and operation of the exhaust gas measuring sensor.

In the sense of the invention, an exhaust gas line is to be understood as a device which is set up to discharge the exhaust gas formed during the combustion of the fuel in the internal combustion engine into the environment. During this removal, the internal combustion engine flows through the exhaust system according to plan in an exhaust gas flow direction and preferably has an exhaust gas pipeline and more preferably a plurality of exhaust gas pipelines for parallel routing of exhaust gases. At least one particle filter is arranged in the exhaust line, through which at least one partial exhaust gas stream or all of the exhaust gas flows through the internal combustion engine into the environment. The particle filter preferably has a base body, which further preferably has a coating, preferably a catalytically active coating. Such particle filters are known from the prior art as so-called gasoline or diesel particle filters or also coated particle filters, the coating of the particle filter being designed in particular in such a way that it is catalytically active.

The exhaust line also has an exhaust gas measurement sensor for measuring exhaust gas properties of the exhaust gas flowing through the exhaust line. On the basis of the exhaust gas properties to be measured, the exhaust gas measurement sensor is designed such that a carrier gas flows through it for the measurement, this carrier gas being mixed with the exhaust gas to be measured before or during the measurement. More preferably, the carrier gas is ionized by the exhaust gas measurement sensor before the measurement and the exhaust gas measurement sensor is set up in particular for measuring the particle number concentration or for measuring the particle mass concentration or both for measuring the particle number concentration and mass concentration. Such an exhaust gas measuring sensor is known in particular from DE 10 2014 015 634 A1 known. In a modification of the device, the measurement of the lung-deposited surface area (LDSA) is also conceivable as a measurement variable.

Due to the system, such an exhaust gas measurement sensor has a carrier gas supply through which the carrier gas can enter the exhaust gas measurement sensor and a sample gas outlet through which at least the carrier gas or the mixture of the measured exhaust gas and the carrier gas can exit the exhaust gas measurement sensor again. The sample gas outlet is thus set up at least to discharge the carrier gas from the exhaust gas measurement sensor.

The exhaust gas measurement sensor is arranged in the exhaust line in relation to the exhaust gas flow direction in such a way that the measurement gas outlet is arranged upstream of the particle filter. Furthermore, the carrier gas used to measure the exhaust gas properties is a non-reactive gas. In the sense of the invention, such a non-reactive gas is to be understood as meaning an inert gas or exhaust gas from the internal combustion engine, since in particular inert gas or exhaust gas leads to no or almost no reactions with the components filtered out of the exhaust gas in the particle filter, and so its loading by the carrier gas becomes temporary unaffected. This non-reactive gas can be supplied to the exhaust gas measuring sensor via a carrier gas supply line. In particular, with such a configuration, measurement results with high quality can be achieved, whereby high quality means in particular that the results recorded with the exhaust gas measurement sensor correspond to the results as shown in would result in a system without exhaust gas measuring sensor.

In a preferred embodiment of the invention, the carrier gas used in the exhaust gas measurement sensor is an inert gas, preferably this inert gas is nitrogen, or molecular di-nitrogen. Depending on the supplied non-reactive gas (inert gas), the carrier gas supply line can be referred to as an inert gas supply line.

The exhaust line preferably has an inert gas storage, or an inert gas tank, or such an inert gas storage is assigned to the exhaust line in or on the motor vehicle. This inert gas storage device is in particular set up for receiving the non-reactive gas, which can be supplied to the exhaust gas measurement sensor for purging it. More preferably, the exhaust line has an inert gas metering valve, or such an inert gas valve is assigned to the exhaust line in or on the motor vehicle. In this sense, “assigned” means that the assigned elements functionally interact with the exhaust line. Further preferably, “in or on the motor vehicle” is not only to be understood as an only temporary, that is to say temporary, recording in or on the motor vehicle, in particular for a test drive or a test cycle. In particular, the inert gas accumulator and preferably also the inert gas metering valve can be accommodated in a measuring device which can be accommodated in the trunk or in the interior of the motor vehicle or which is preferably on a rear carrier device, preferably on a trailer coupling or by means of a towing eye or by means of a vehicle body component a trunk lid, mounted holder or the like, is receivable on the motor vehicle.

In particular, by means of such an embodiment of the invention, an inert gas can be fed to the exhaust gas measurement sensor in a simple manner and used as a carrier gas. The inert gas is preferably conditioned in or on the motor vehicle or preferably outside of the motor vehicle, in particular brought to a predetermined initial state, and it can thus be ensured that this has no influence on the measurement results of the exhaust gas measurement sensor, since it is supplied to it in a quasi-standardized state .

In a preferred embodiment of the invention, exhaust gas from the exhaust line is used as carrier gas, and further preferably the exhaust line has a carrier gas extraction point with which exhaust gas can be extracted from this. According to the supplied non-reactive gas (exhaust gas), the carrier gas supply line can be referred to as an exhaust gas supply line. In this embodiment, the exhaust gas line preferably has an exhaust gas supply line, by means of which the exhaust gas removed from the exhaust gas line can be supplied from the carrier gas removal point to the exhaust gas measurement sensor as carrier gas via the carrier gas supply; such a line can also be referred to as an exhaust gas supply line. In particular, exhaust gas from the exhaust line has already reacted with the fuel in the combustion chamber of the internal combustion engine and is not or only slightly reactive with the substances from the exhaust gas deposited in the particle filter and thus does not influence the loading of the particle filter. There is also "sufficient" exhaust gas in the exhaust system and "refilling" or "refilling", as would be necessary in particular when using conditioned inert gas from an inert gas storage, can be omitted.

In a preferred embodiment, a carrier gas treatment device is arranged in the exhaust gas supply line, which is set up to supply exhaust gas from the carrier gas extraction point to the carrier gas supply. The carrier gas treatment device is preferably set up to dehumidify the extracted exhaust gas and further preferably the carrier gas treatment device is set up to clean the removed exhaust gas and the carrier gas treatment device is preferably set up to dehumidify and clean the removed exhaust gas. The cleaning of the exhaust gas is of particular importance since the exhaust gas used should be as particle-free as possible. A high-efficiency particulate filter (HEPA filter) is preferably provided for filtering the exhaust gas used as carrier gas. In particular, by conditioning the extracted exhaust gas in the carrier gas processing device, it can be achieved that the exhaust gas supplied to the exhaust gas measurement sensor as carrier gas does not influence the loading or the measurement results or only influences it slightly. Further preferably, a delivery device, preferably a pump device, is arranged in the exhaust gas supply line, which is set up for the targeted delivery of exhaust gas through the exhaust gas supply line for the carrier gas supply of the exhaust gas measurement sensor.

In a preferred embodiment of the invention, the carrier gas extraction point is arranged upstream of the particle filter, based on the exhaust gas flow direction of the exhaust line. In particular with such an arrangement of the carrier gas extraction point, the exhaust gas measurement sensor, which is also arranged upstream of the particle filter, is at the same or at least at a similar pressure level as the carrier gas extraction point and the exhaust gas used as carrier gas is conveyed by the Exhaust gas supply line is made possible with little effort.

In a preferred embodiment of the invention, the carrier gas extraction point, in relation to the exhaust gas flow direction of the exhaust line, is arranged downstream of the sample gas outlet, the exhaust gas measurement sensor being arranged upstream of the exhaust gas particle filter.

In a preferred embodiment of the invention, the carrier gas extraction point is arranged upstream of the sample gas outlet, based on the exhaust gas flow direction of the exhaust line. In particular, in the case of a carrier gas extraction point arranged upstream of the sample gas outlet, there is generally a pressure drop from the carrier gas extraction point to the sample gas outlet, which promotes a flow of the exhaust gas used as carrier gas through the exhaust gas measurement sensor.

In a preferred embodiment of the invention, the carrier gas extraction point is arranged downstream of the particle filter, based on the direction of exhaust gas flow through the exhaust line. In other words, the exhaust gas first flows through the particle filter and is cleaned by it, or at least pre-cleaned, and is only then removed via the carrier gas extraction point and fed to the exhaust gas measurement sensor. In this embodiment, too, a carrier gas processing device can preferably also be provided. In particular in the case of a carrier gas extraction point arranged downstream of the particle filter, the exhaust gas used as carrier gas has already been pre-cleaned.

Furthermore, a motor vehicle internal combustion engine is provided, which has an exhaust line according to one of the previously described embodiments. A good measurement of the exhaust gas properties is made possible in particular by the described construction of the exhaust gas line; the loading of the particle filter is not influenced by the exhaust gas measurement.

The invention can be extended analogously to an exhaust gas system with several lines. For this purpose, several exhaust gas measuring sensors can be installed in the system at the same time. Further preferably, exhaust gas measurement sensors are installed simultaneously before and after such a particle filter. Further preferably, it is possible to install one or more exhaust gas measurement sensors in different lines of such an exhaust system. In particular, such a design makes it possible to operate these exhaust gas measurement sensors with a single extraction point or conveying device, etc., and to supply them with non-reactive gas.

• 1: Eine schematisierte Darstellung einer ersten Ausführungsform der Erfindung,
• 2: Eine schematisierte Darstellung einer zweiten Ausführungsform der Erfindung,
• 3: Eine schematisierte Darstellung einer dritten Ausführungsform der Erfindung,
• 4: Eine schematisierte Darstellung einer vierten Ausführungsform der Erfindung,
• 5: Am Kraftfahrzeug angeordneter und dem Abgasstrang zugeordneter Inertgasspeicher.

Individual features and embodiments of the invention are explained in more detail below with reference to the figures, in which case:

• 1 : A schematic representation of a first embodiment of the invention,
• 2nd : A schematic representation of a second embodiment of the invention,
• 3rd : A schematic representation of a third embodiment of the invention,
• 4th : A schematic representation of a fourth embodiment of the invention,
• 5 : Inert gas storage arranged on the motor vehicle and assigned to the exhaust line.

In 1 is a schematic representation of a first embodiment of the invention. The exhaust line points to the targeted guidance of the exhaust gas flow 8th from the internal combustion engine 9 an exhaust pipe in the environment 3rd with a particle filter 2nd on. The particle filter 2nd is for filtering out small solid particles, especially soot particles, from this exhaust gas flow 8th set up.

An exhaust gas measuring sensor is used to measure exhaust gas properties 1 in this exhaust pipe 3rd arranged. The exhaust gas measuring sensor 1 has a carrier gas supply 6 through which a carrier gas required for exhaust gas measurement into the exhaust gas measurement sensor 1 can flow in. The exhaust gas measuring sensor also has 1 a sample gas outlet 7 through which a mixture of measured exhaust gas and carrier gas into the exhaust pipe 3rd and thus into the exhaust gas flow 8th is fired.

The exhaust line has the exhaust gas feed line for supplying carrier gas 12th with which from the exhaust pipe 3rd at the carrier gas sampling point 14 Exhaust gas is removed. In the exhaust gas supply line 12th is the carrier gas processing device 4th arranged with which the extracted exhaust gas is cleaned and dehumidified before it from the carrier gas delivery device 5 via the carrier gas supply 6 as carrier gas in the exhaust gas measuring sensor 1 is promoted.

In the exhaust gas measuring sensor 1 becomes the particle number concentration and / or the particle mass concentration and / or the LDSA of the exhaust gas flow 8th determined before this exhaust gas flow 8th through the particle filter 2nd occurs. Via the sample gas outlet 7 occurs, due to the measuring principle of the exhaust gas measuring sensor 1 , a mixture of carrier gas (cleaned and dehumidified exhaust gas) and exhaust gas to be measured back into the exhaust gas flow 8th out. Here is the sample gas outlet 7 upstream to the particle filter 2nd arranged and all exhaust gas from the internal combustion engine 9 is through the particle filter 2nd cleaned.

In 2nd is a schematic representation of a second embodiment of the invention. The exhaust line points to the targeted guidance of the exhaust gas flow 8th from the internal combustion engine 9 an exhaust pipe in the environment 3rd with a particle filter 2nd on. The particle filter 2nd is for filtering out small solid particles, especially soot particles, from this exhaust gas flow 8th set up. The second embodiment ( 2nd ) of the invention differs from the first embodiment ( 1 ) regarding the arrangement of the carrier gas sampling point 14 and the carrier gas supply 6 , or the sample gas outlet 7 .

The carrier gas sampling point 14 is based on the exhaust gas flow 8th , downstream of the exhaust gas measuring sensor 1 and thus downstream to the sample gas outlet 7 arranged. Regarding the further components of this embodiment, reference is made to the in 1 illustrated embodiment referred.

In 3rd is a schematic representation of a third embodiment of the invention. The exhaust line points to the targeted guidance of the exhaust gas flow 8th from the internal combustion engine 9 an exhaust pipe in the environment 3rd with a particle filter 2nd on. The particle filter 2nd is for filtering out small solid particles, especially soot particles, from this exhaust gas flow 8th set up. The third embodiment ( 3rd ) of the invention differs from the first embodiment ( 1 ) regarding the arrangement of the carrier gas sampling point 14 and the carrier gas supply 6 or the sample gas outlet 7 .

The carrier gas sampling point 14 is based on the exhaust gas flow 8th , downstream to the particulate filter 2nd arranged, ie it is only cleaned or pre-cleaned exhaust gas via the carrier gas extraction point 14 from the exhaust gas flow 8th taken. Regarding the further components of this embodiment, reference is made to the in 1 illustrated embodiment referred.

In 4th shows a fourth embodiment of the invention. The exhaust line points to the targeted guidance of the exhaust gas flow 8th from the internal combustion engine 9 an exhaust pipe in the environment 3rd with a particle filter 2nd on. The particle filter 2nd is for filtering out small solid particles, especially soot particles, from this exhaust gas flow 8th set up. The fourth embodiment ( 4th ) of the invention differs from the first embodiment ( 1 ) with regard to the introduced carrier gas. In the fourth embodiment, the carrier gas used is molecular nitrogen N ₂ , that is to say an inert gas, and not exhaust gas as in the embodiments 1 to 3rd .

This inert gas is in the inert gas tank 10th stored and is via an inert gas connection 15 the exhaust gas measuring sensor 1 controlled via the carrier gas metering valve 11 and the inert gas supply line 13 fed. The inert gas connection 15 can be a standardized connection, so that it is easy to use an inert gas tank designed as a gas bottle 10th to connect to it. The inert gas serving as carrier gas passes through the carrier gas supply 6 in the exhaust gas measuring sensor 1 on and after the exhaust gas measurement via the sample gas outlet 7 out again. Regarding the further components of this embodiment, reference is made to the in 1 illustrated embodiment referred.

In 5 An embodiment of the invention is shown, in which the inert gas tank (not shown) and the inert gas metering valve (not shown) and further elements of a measuring device 16 on the motor vehicle 17th are temporarily arranged. In the proposed embodiment, the rear carrier device 18th designed as a trailer hitch. With such an embodiment of the invention, the motor vehicle is particularly simple 17th for a test facility on a test bench or on the road and to carry out measurements with the exhaust gas measurement sensor in this test facility. From the exhaust line 3rd occurs the exhaust gas flow measured by the exhaust gas measuring sensor (not shown) 8th in the direction of travel of the motor vehicle 17th towards the back. From the measuring device 16 is the exhaust line 3rd and thus the exhaust gas measuring sensor, through the inert gas supply line 13 , can be supplied with non-reactive gas for the measurement. The exhaust gas measuring sensor through the inert gas supply line 13 The amount of non-reactive gas supplied can be regulated via the inert gas metering valve.

Reference list

1

Exhaust gas measurement sensor

2nd

Particle filter

3rd

Exhaust pipe

4th

Carrier gas processing device

5

Carrier gas conveyor

6

Carrier gas supply

7

Sample gas outlet

8th

Exhaust gas flow

9

Internal combustion engine

10th

Inert gas tank

11

Carrier gas metering valve

12th

Exhaust gas supply line

13

I nert gas supply line

14

Carrier gas sampling point

15

Inert gas connection

16

Measuring device with inert gas tank and inert gas metering valve

17th

Motor vehicle

18th

Rear carrier device

QUOTES INCLUDE IN THE DESCRIPTION

This list of documents listed by the applicant has been generated automatically and is only included for better information for 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 102014015634 A1 [0001, 0010]

Claims (9)

Exhaust system of an internal combustion engine (9) for a motor vehicle with a particle filter (12), the exhaust system for guiding exhaust gas from the internal combustion engine (9) into the environment in an exhaust gas flow direction and having an exhaust gas measurement sensor (1) for measuring exhaust gas properties, wherein this exhaust gas measurement sensor (1) for measuring the exhaust gas properties is flowed through by a carrier gas and has a carrier gas supply (6) and a sample gas outlet (7), the sample gas outlet (7) being set up for discharging at least the carrier gas from the exhaust gas measurement sensor (1), thereby characterized in that the exhaust gas measuring sensor (1), in relation to the exhaust gas flow direction, is arranged in the exhaust line such that the measuring gas outlet (7) is arranged upstream of the particle filter (2) and that the carrier gas is a non-reactive gas. Exhaust system after Claim 1 , characterized in that the carrier gas is an inert gas. Exhaust system after Claim 1 , characterized in that the exhaust gas line has a carrier gas extraction point (14) with which exhaust gas can be extracted from the exhaust gas line and an exhaust gas supply line (12) with which this exhaust gas from the carrier gas extraction point (14) passes to the exhaust gas measurement sensor (1) via the carrier gas supply (6) can be supplied as carrier gas. Exhaust system after Claim 3 , characterized in that a carrier gas treatment device (4) is arranged in the exhaust gas supply line (12), that this is set up at least for cleaning or at least for dehumidifying or for cleaning and dehumidifying exhaust gas guided in the exhaust gas supply line (12). Exhaust system according to one of the Claims 3 or 4th , characterized in that the carrier gas extraction point (14), based on the exhaust gas flow direction, is arranged upstream of the particle filter (2). Exhaust system after Claim 5 , characterized in that the carrier gas extraction point (14), relative to the exhaust gas flow direction, is arranged downstream of the sample gas outlet. Exhaust system after Claim 5 , characterized in that the carrier gas extraction point (14), relative to the exhaust gas flow direction, is arranged upstream of the sample gas outlet (7). Exhaust system according to one of the Claims 3 or 4th , characterized in that the carrier gas extraction point (14), relative to the exhaust gas flow direction, is arranged downstream of the particle filter (2). Motor vehicle internal combustion engine with an exhaust line according to one of the preceding claims.

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