DE102019126746B4 - Exhaust pipe arrangement of an internal combustion engine - Google Patents

Abstract

Exhaust line arrangement (1) of an internal combustion engine (2), at least comprising an exhaust line (3) running along a direction of flow (4) starting from a first end (5) connected to the internal combustion engine (2) and towards a second end (6) of an exhaust gas (7) of the internal combustion engine (2) can flow through, at least one NOx adsorber (8) and downstream of which an SCR catalytic converter (9) being arranged in the exhaust pipe (3); wherein the exhaust pipe arrangement (1) comprises a temperature control device (10) which is connected to the exhaust pipe (3) via a first inlet point (11) arranged upstream of the NOx adsorber (8) and between the NOx adsorber (8) and the SCR Catalyst (9) arranged second introduction point (12), wherein a heated gas (13) can be fed into the exhaust pipe (3) at least optionally via the first introduction point (11) or the second introduction point (12) via the temperature control device (10). ; wherein the SCR catalytic converter (9) can be heated by the temperature control device (10) to a minimum temperature, referred to as the first limit temperature, which is at least required for converting the nitrogen oxides; wherein the gas (13) via the second inlet point (12) for heating the SCR catalytic converter (9) and, as soon as the SCR catalytic converter (9) exceeds a second limit temperature which corresponds at least to the first limit temperature, via the first inlet point (11 ) for heating the NOx adsorber (8) is conductive; wherein at least - the gas (13) can be heated outside the exhaust pipe (3) if necessary, or - the temperature control device (10) comprises a burner or an electric heating device.

Description

The invention relates to an exhaust pipe arrangement of an internal combustion engine, in particular in a motor vehicle. The internal combustion engine is in particular a diesel engine.

There is a constant need to reduce or avoid pollutant emissions when operating internal combustion engines. There is a current need to reduce nitrogen oxide (NOx) emissions, especially when driving dynamically and when the exhaust gas aftertreatment is cold or not fully active. This problem is exacerbated even further, especially with short-distance operation of the motor vehicle, because then cleaning z. B. a NOx storage while driving is not possible.

The DE 10 2007 039 081 A1 is directed to an internal combustion engine system in a motor vehicle. The internal combustion engine system includes a reformer for generating hydrogen gas and a reformate introduction device for introducing the reformate gas into an exhaust pipe, an ignition element for igniting the reformate gas being provided in the exhaust pipe and downstream of the introduction point and upstream of an exhaust gas treatment device. The internal combustion engine is operated depending on the supply of the reformate gas.

From the DE 10 2016 205 182 A1 a method for exhaust gas aftertreatment is known. A NOx storage catalyst is arranged in an exhaust pipe. To regenerate the NOx storage catalytic converter, the exhaust gas can be diverted to a bypass, with the NOx storage catalytic converter being regenerated by a reformate gas.

The EP 1 594 594 B1 is directed to a system for reducing NOx. The system includes an internal combustion engine with an exhaust pipe in which a NOx adsorber and an SCR catalytic converter can be arranged one after the other.

The DE 10 2016 210 188 A1 discloses a method for aftertreatment of exhaust gas from an internal combustion engine.

The object of the present invention is to at least partially solve the problems cited with reference to the prior art. In particular, an exhaust pipe arrangement is to be proposed through which pollutant emissions can be further reduced or prevented. In particular, the NOx emissions should be reduced or prevented over short distances and during cold departures.

An exhaust pipe arrangement with the features according to patent claim 1 contributes to the solution of these tasks. Advantageous developments are the subject matter of the dependent patent claims. The features listed individually in the patent claims can be combined with one another in a technologically meaningful manner and can be supplemented by explanatory facts from the description and/or details from the figures, with further embodiment variants of the invention being shown.

An exhaust pipe arrangement of an internal combustion engine is proposed. The exhaust gas line arrangement comprises at least one exhaust gas line through which an exhaust gas of the internal combustion engine can flow along a flow direction starting from a first end connected to the internal combustion engine and towards a second end. At least one NOx adsorber and, downstream thereof, an SCR catalytic converter are arranged in the exhaust pipe. The exhaust gas line arrangement also includes a temperature control device which is connected to the exhaust gas line via a first inlet point arranged upstream of the NOx adsorber and a second inlet point arranged between the NOx adsorber and the SCR catalytic converter. A heated gas can be introduced at least selectively via the first introduction point or the second introduction point into the exhaust pipe via the temperature control device.

The internal combustion engine is in particular a diesel engine.

The exhaust pipe is in particular arranged immediately downstream of the internal combustion engine with respect to a direction of flow of the exhaust gas generated by the internal combustion engine. The exhaust gas is collected via the exhaust gas line and discharged to an environment via exhaust gas treatment units.

Exhaust gas treatment units are known in principle. Exhaust gas treatment units are components that are arranged in the exhaust gas line and are intended to convert or store pollutants in the exhaust gas. As exhaust gas treatment units z. B. storage, ie NOx storage or NOx adsorber, particle filter, particle traps and catalysts. Multi-way or one-way catalysts can be used as catalysts. In doing so, e.g. B. oxidation catalysts, diesel oxidation catalysts and SCR catalysts (Selective Catalytic Reaction) are used.

The exhaust gas enters the exhaust pipe via a first end and exits to the environment via a second end. Between the first end At least two exhaust gas treatment units are arranged at the second end, at least one NOx adsorber, ie a storage device for nitrogen oxides, and at least one SCR catalytic converter.

The NOx adsorber is used in particular for at least temporarily storing nitrogen oxides. The nitrogen oxides are separated from the exhaust gas and retained in the NOx adsorber.

The NOx adsorber is arranged in particular directly downstream of the first introduction point.

The NOx adsorber is arranged in particular directly upstream of the second introduction point.

The SCR catalytic converter is used in particular to convert nitrogen oxides. In particular, ammonia is added as a reactant to the exhaust gas upstream of an SCR catalytic converter. A minimum temperature is required at least for the conversion of the nitrogen oxides in the SCR catalytic converter. This minimum temperature is referred to below as the first limit temperature.

The SCR catalytic converter can in particular comprise at least one hydrolysis catalytic converter arranged upstream, for converting an added urea-water solution into ammonia, and an ammonia blocking catalytic converter arranged downstream.

The SCR catalytic converter is arranged in particular directly downstream of the second introduction point.

In particular, a temperature control arrangement is provided with which a heated gas can be supplied to the exhaust pipe. The heated gas is used to heat an exhaust aftertreatment component. If necessary, the gas is heated outside of the exhaust pipe and introduced into the exhaust pipe at least optionally via the first introduction point or the second introduction point.

If the heated gas is introduced into the exhaust gas line via the first introduction point, the NOx adsorber arranged downstream of the first introduction point can be heated. If the heated gas is introduced into the exhaust gas line via the second introduction point, the SCR catalytic converter arranged downstream of the second introduction point can be heated.

In particular, the SCR catalytic converter should be heated to a minimum temperature by the temperature control device, which is at least required for the conversion of the nitrogen oxides, e.g. B. at least 130 degrees Celsius, preferably at least 180 degrees Celsius. This minimum temperature is referred to as the first limit temperature.

In particular, the temperature control device is operated at least until the SCR catalytic converter has reliably and completely reached the first limit temperature. In particular, the heated gas is applied to the SCR catalytic converter until the SCR catalytic converter exceeds a second limit temperature. The second limit temperature corresponds at least to the first limit temperature. In order to prevent the SCR catalytic converter from cooling down in the meantime, e.g. B. due to switching between the second point of introduction and the first point of introduction, the second limit temperature should be greater than the first limit temperature, z. B. by at least 10 Kelvin, preferably at least 20 Kelvin.

In particular, after the SCR catalytic converter has exceeded the second limit temperature, the temperature control device is switched over so that the heated gas can be introduced into the exhaust gas line via the first introduction point upstream of the NOx adsorber. In particular, the heated gas is applied to the NOx adsorber until the NOx adsorber exceeds a third limit temperature.

The third limit temperature is in particular the minimum temperature from which desorption of the nitrogen oxides stored in the NOx adsorber begins. The heating of the NOx adsorber above the third limit temperature means that the nitrogen oxides stored in the NOx adsorber are desorbed and get back into the exhaust gas. The nitrogen oxides thus reach the already sufficiently heated SCR catalytic converter further downstream and can be converted. In this way, NOx emissions can at least be reduced or even prevented.

In particular, a very rapid heating of the relevant exhaust gas aftertreatment units is possible via the temperature control device, so that z. B. at short distances and also during a cold departure, NOx emissions can at least be reduced or even prevented.

The temperature control device or at least the first introduction point is arranged in particular in the underbody area of a motor vehicle, preferably at a distance along the exhaust pipe of at least 100 centimeters from the first end of the exhaust pipe or from an outlet of the nearest combustion chamber of the internal combustion engine.

In particular, it is also possible to quickly heat up exhaust gas aftertreatment units that are located at a large distance from the combustion engine voltage engine are arranged and heat accordingly slowly by the exhaust gas.

In particular, the temperature control device includes a fan, through which the heated gas can be transported from the temperature control device into the exhaust pipe. In particular, operation of the temperature control device and heating of the exhaust gas aftertreatment units is also possible when the internal combustion engine is at a standstill.

In particular, the SCR catalytic converter can be acted upon by the heated gas in partial flow or in full flow. In the partial flow, only part of the cross section through which the SCR catalytic converter can flow is acted upon, with the full cross section through which the flow can flow being acted upon.

In particular, a thermal output of the temperature control device is between 10 and 100 kilowatts, in particular between 20 and 70 kilowatts, preferably between 30 and 50 kilowatts. In particular, this applies to a rated output of the internal combustion engine of up to 200 kilowatts.

In particular, the thermal power per 100 kilowatts of nominal power of the internal combustion engine is 5 to 50 kilowatts, in particular 10 to 35 kilowatts, preferably 15 to 25 kilowatts.

In particular, a volume of the NOx adsorber that can be acted upon by the exhaust gas is 0.7 to 2 cu.

In particular, only the first point of introduction or only the second point of introduction can be used for introducing the heated gas into the exhaust pipe due to the temperature control device.

In particular, only the first point of introduction or only the second point of introduction or else both points of introduction can be used at the same time for introducing the heated gas into the exhaust pipe by means of the temperature control device. In particular, a volume flow of the heated gas can be divided between the first point of introduction and the second point of introduction in a controllable manner.

In particular, the temperature control device includes a burner for generating a warm exhaust gas, the exhaust gas being able to be fed to the exhaust pipe as heated gas. The burner can B. be operated with a fuel. Alternatively, other heating means can be used to generate the heated gas, e.g. B. electric heaters.

In particular, the temperature control device comprises at least one switching device, through which the gas can be routed either to the first point of introduction or to the second point of introduction. In particular, the switching device comprises at least one flap through which the gas can be routed to the first point of introduction or to the second point of introduction. In particular, a flap is provided for each discharge point.

In particular, the switching device comprises at least one or more controllable flaps, so that a volume flow of the heated gas can be controllably divided between the first inlet point and the second inlet point.

In particular, a first reactant introduction point for introducing a reactant into the exhaust line is arranged along the exhaust line between the second introduction point and the SCR catalytic converter.

In particular, a particle filter with SCR activity is arranged along the exhaust line upstream of the first introduction point, a second reactant introduction point for introducing a reactant into the exhaust line being arranged upstream of the particle filter.

The reactant comprises in a known manner, for. B. a hydrocarbon, ammonia, or a urea-water solution.

The reactant is particularly suitable for converting nitrogen oxides, particularly in connection with an SCR catalytic converter or an exhaust gas aftertreatment unit with SCR activity.

1. a) Ermitteln einer Temperatur zumindest des SCR-Katalysators und, wenn die Temperatur unterhalb einer ersten Grenztemperatur liegt,
2. b) Betreiben der Temperiereinrichtung und Zuleiten des erwärmten Gases über die zweite Einleitstelle zur Erwärmung des SCR-Katalysators und, sobald der SCR-Katalysator eine zweite Grenztemperatur überschreitet,
3. c) Zuleiten des erwärmten Gases über die erste Einleitstelle zur Erwärmung des NOx-Adsorbers.

A method for operating the described exhaust pipe arrangement is also proposed. The procedure comprises at least the following steps:

1. a) determining a temperature of at least the SCR catalytic converter and, if the temperature is below a first limit temperature,
2. b) operating the temperature control device and feeding in the heated gas via the second inlet point to heat the SCR catalytic converter and as soon as the SCR catalytic converter exceeds a second limit temperature,
3. c) Feeding in the heated gas via the first introduction point for heating the NOx adsorber.

Reference is made to the statements on the arrangement of the exhaust pipe.

The above (non-exhaustive) classification of the process steps into a) to c) should primarily only serve to differentiate and do not enforce any order and/or dependency. The frequency of the process steps, e.g. B. during setup and / or operation of the system may vary. It is also possible for method steps to at least partially overlap one another in terms of time. Process steps a) and b) very particularly preferably take place at the same time and step c) takes place at a different time than steps a) and b). Steps b) and c) can be conditional and possibly only executed if the condition specified in the previous step a) or b) is met. In particular, steps a) to c) are carried out in the order listed.

In particular, in step b) the heated gas is conducted exclusively via the second introduction point and in step c) exclusively via the first introduction point.

A parallel introduction of the heated gas via the first introduction point and the second introduction point is, in particular, alternatively or additionally possible within the scope of the method.

The method can be carried out by a control unit of a motor vehicle. Furthermore, the method can also be carried out by a computer or with a processor of a control unit.

Accordingly, a system for data processing is also proposed which includes a processor which is adapted/configured in such a way that it carries out the method or part of the steps of the proposed method.

A computer-readable storage medium can be provided which comprises instructions which, when executed by a computer/processor, cause the latter to carry out the method or at least part of the steps of the proposed method.

A motor vehicle is also proposed, at least comprising an internal combustion engine and the exhaust gas line arrangement described and connected to the internal combustion engine.

In particular, the motor vehicle additionally includes a control unit that is suitably equipped or configured or programmed to carry out the described method.

The explanations regarding the exhaust pipe arrangement can be transferred in particular to the method, the motor vehicle or the computer-implemented method (ie the computer or the processor, the data processing system, the computer-readable storage medium) and vice versa.

The use of indefinite articles (“a”, “an”, “an” and “an”), particularly in the claims and the description reflecting them, is to be understood as such and not as a numeral. Correspondingly introduced terms or components are to be understood in such a way that they are present at least once and in particular can also be present several times.

As a precaution, it should be noted that the numerals used here (“first”, “second”, ...) primarily (only) serve to distinguish between several similar objects, sizes or processes, i.e. in particular no dependency and/or sequence of these objects, sizes or make processes mandatory for each other. Should a dependency and/or order be necessary, this is explicitly stated here or it is obvious to the person skilled in the art when studying the specifically described embodiment. If a component can occur several times (“at least one”), the description of one of these components can apply equally to all or part of the majority of these components, but this is not mandatory.

• 1: ein bekanntes Kraftfahrzeug;
• 2 ein Kraftfahrzeug mit einer Abgasleitungsanordnung in einem ersten Zustand;
• 3: das Kraftfahrzeug nach 2 mit einer Abgasleitungsanordnung in einem zweiten Zustand;
• 4: das Kraftfahrzeug nach 2 und 3 mit einer Abgasleitungsanordnung in einem dritten Zustand;
• 5: das Kraftfahrzeug nach 2 bis 4 mit einer Abgasleitungsanordnung in einem vierten Zustand.

The invention and the technical environment are explained in more detail below with reference to the attached figures. It should be pointed out that the invention should not be restricted by the exemplary embodiments given. In particular, unless explicitly stated otherwise, it is also possible to extract partial aspects of the facts explained in the figures and to combine them with other components and findings from the present description. In particular, it should be pointed out that the figures and in particular the proportions shown are only schematic. Show it:

• 1 : a well-known motor vehicle;
• 2 a motor vehicle with an exhaust pipe arrangement in a first state;
• 3 : the motor vehicle after 2 with an exhaust pipe arrangement in a second state;
• 4 : the motor vehicle after 2 and 3 with an exhaust pipe arrangement in a third state;
• 5 : the motor vehicle after 2 until 4 with an exhaust pipe arrangement in a fourth state.

The 1 shows a known motor vehicle 19 with an exhaust pipe arrangement 1. The exhaust pipe arrangement 1 comprises an exhaust pipe 3, through which an exhaust gas 7 of the internal combustion engine 2 can flow along a flow direction 4 starting from a first end 5 connected to the internal combustion engine 2 and towards a second end 6 . Starting from the first end 5, an exhaust gas turbocharger 24, a heated catalytic converter 26, a diesel oxidation catalytic converter 27, a second reactant introduction point 18, a particle filter 17 with SCR activity, a first reactant introduction point 16 and an SCR catalytic converter 9 are arranged in succession in the exhaust pipe 3 . The internal combustion engine 2 is a diesel engine. The exhaust pipe 7 is connected to the exhaust side of the internal combustion engine 2 . A fresh air duct 23 is connected to the intake side of the internal combustion engine 2 . Fresh air 21 enters the fresh air line 23 via an air filter 22 and is supplied to the internal combustion engine 2 via an exhaust gas turbocharger 24 and an intercooler 25 .

2 shows a motor vehicle 19 with an exhaust pipe arrangement 1 in a first state. 3 shows the motor vehicle 19 after 2 with an exhaust pipe arrangement 1 in a second state. 4 shows the motor vehicle 19 after 2 and 3 with an exhaust pipe arrangement 1 in a third state. 5 shows the motor vehicle 19 after 2 until 4 with an exhaust pipe arrangement 1 in a fourth state. The 2 until 5 are described together below. To the remarks 1 is referred to.

In contrast to 1 A NOx adsorber 8 is additionally arranged in the exhaust line 3 upstream of the SCR catalytic converter 9 . The exhaust pipe arrangement 1 also includes a temperature control device 10 which is connected to the exhaust pipe 3 via a first inlet point 11 arranged upstream of the NOx adsorber 8 and a second inlet point 12 arranged between the NOx adsorber 8 and the SCR catalytic converter 9 . A heated gas 13 can be introduced into the exhaust pipe 3 at least optionally via the first introduction point 11 or the second introduction point 12 via the temperature control device 10 . The temperature control device 10 is regulated or controlled via a control unit 20 .

The temperature control device 10 comprises a burner 14 for generating a warm exhaust gas, the exhaust gas being able to be fed to the exhaust pipe 3 as heated gas 13 .

The temperature control device 10 includes a switching device 15 through which the gas 13 can be routed either to the first point of introduction 11 or to the second point of introduction 12 . The switching device 15 comprises an adjustable first flap 28 through which the gas 13 can be directed to the first introduction point 11 and an adjustable second flap 29 through which the gas 13 can be guided to the second introduction point 12 .

In the first state according to 2 the heated gas 13 is transferred into the exhaust pipe 3 via both inlet points 11, 12.

In the second state according to 3 the temperature control device 10 is out of operation, so that no gas 13 is heated.

In the third state according to 4 the heated gas 13 is transferred into the exhaust pipe 3 only via the second introduction point 12 .

In the fourth state according to 5 the heated gas 13 is transferred into the exhaust pipe 3 only via the first introduction point 11 .

If the heated gas 13 is introduced into the exhaust pipe 3 via the first introduction point 11, the NOx adsorber 8 arranged downstream of the first introduction point 11 can be heated. If the heated gas 13 is introduced into the exhaust pipe 3 via the second introduction point 12, the SCR catalytic converter 9 arranged downstream of the second introduction point 12 can be heated.

Reference List

1

exhaust pipe arrangement

2

internal combustion engine

3

exhaust pipe

4

flow direction

5

first end

6

second end

7

exhaust

8th

NOx adsorber

9

SCR catalytic converter

10

temperature control device

11

first entry point

12

second entry point

13

gas

14

burner

15

switching device

16

first reactant introduction point

17

particle filter

18

second reactant introduction point

19

motor vehicle

20

control unit

21

fresh air

22

air filter

23

fresh air line

24

exhaust gas turbocharger

25

intercooler

26

heated catalyst

27

oxidation catalyst

28

first take

29

second flap

Claims (8)

Exhaust line arrangement (1) of an internal combustion engine (2), at least comprising an exhaust line (3) running along a direction of flow (4) starting from a first end (5) connected to the internal combustion engine (2) and towards a second end (6) of an exhaust gas (7) of the internal combustion engine (2) can flow through, at least one NOx adsorber (8) and downstream of which an SCR catalytic converter (9) being arranged in the exhaust pipe (3); wherein the exhaust pipe arrangement (1) comprises a temperature control device (10) which is connected to the exhaust pipe (3) via a first inlet point (11) arranged upstream of the NOx adsorber (8) and between the NOx adsorber (8) and the SCR Catalyst (9) arranged second introduction point (12), wherein a heated gas (13) can be fed into the exhaust pipe (3) at least optionally via the first introduction point (11) or the second introduction point (12) via the temperature control device (10). ; wherein the SCR catalytic converter (9) can be heated by the temperature control device (10) to a minimum temperature, referred to as the first limit temperature, which is at least required for converting the nitrogen oxides; wherein the gas (13) via the second inlet point (12) for heating the SCR catalytic converter (9) and, as soon as the SCR catalytic converter (9) exceeds a second limit temperature which corresponds at least to the first limit temperature, via the first inlet point (11 ) for heating the NOx adsorber (8) is conductive; where at least - The gas (13) can be heated outside the exhaust pipe (3) if necessary, or - The temperature control device (10) comprises a burner or an electric heating device. Exhaust line arrangement (1) according to Claim 1 , wherein the temperature control device (10) comprises at least one switching device (15) through which the gas (13) can be selectively routed to the first inlet point (11) or to the second inlet point (12). Exhaust line arrangement (1) according to one of the preceding claims, wherein a first reactant inlet point (16) for introducing a reactant into the exhaust line (3) is arranged along the exhaust line (3) between the second inlet point (12) and the SCR catalytic converter (9). . Exhaust line arrangement (1) according to one of the preceding claims, wherein a particle filter (17) with SCR activity is arranged along the exhaust line (3) upstream of the first introduction point (11), wherein upstream of the particle filter (17) there is a second reactant introduction point (18) for Introduction of a reactant is arranged in the exhaust pipe (3). Method for operating an exhaust pipe arrangement (1) according to one of the preceding claims, at least comprising the following steps: a) determining a temperature of at least the SCR catalytic converter (9) and, if the temperature is below a first limit temperature, b) operating the temperature control device (10) and feeding in the heated gas (13) via the second inlet point (12) to heat the SCR catalytic converter (9) and as soon as the SCR catalytic converter (9) exceeds a second limit temperature, c) supplying the heated gas (13) via the first introduction point (11) to heat the NOx adsorber (8). procedure after Claim 5 , wherein the heated gas (13) in step b) is passed exclusively through the second inlet point (12) and in step c) exclusively through the first inlet point (11). Motor vehicle (19), at least comprising an internal combustion engine (2) and an exhaust pipe arrangement (1) connected thereto according to one of the preceding patent claims 1 until 4 . Motor vehicle (19) after Claim 7 , additionally comprising a control unit (20) for carrying out the method according to any one of the preceding patent claims 5 and 6 is suitably equipped.

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