DE102010008277B4 - Exhaust system of an internal combustion engine - Google Patents

Abstract

Exhaust system (10) of an internal combustion engine, with a first exhaust line (13) assigned to a first cylinder group (11) of the internal combustion engine and with a second exhaust line (14) assigned to a second cylinder group (12) of the internal combustion engine, each exhaust line (13, 14) being at least an exhaust gas purification device (15, 16; 15a, 15b; 16a, 16b) downstream of the respective cylinder group and at least one silencer (17, 18) downstream of the respective exhaust gas purification device (15, 16; 15a, 15b; 16a, 16b), characterized in that that each exhaust line (13, 14) comprises a NOx storage catalytic converter (19, 20) arranged downstream of the respective silencer (17, 18); each exhaust line (13, 14) comprises a bypass line (29, 30), via which the respective silencer is bypassed (17, 18) exhaust gas from the respective exhaust gas purification device (15, 16; 15a, 15b; 16a, 16b) can be fed to the respective NOx storage catalytic converter (19, 20); each exhaust gas line (13, 14) has one between the respective exhaust gas purification device (15 , 16; 15a, 15b, 16a, 16b) and the respective silencer (17, 18) switched shut-off device (31, 32; 31a, 31b, 32a, 32b), which depends on an operating point in which the exhaust system (10) and / or the internal combustion engine is operated, is closed or open.

Description

The invention relates to an exhaust system of an internal combustion engine according to the preamble of claim 1.

From the DE 102 44 021 A1 as well as the DE 10 2007 026 812 A1 Exhaust systems of an internal combustion engine are known according to the preamble of claim 1.

US 5,325,666 A discloses another exhaust system of an internal combustion engine. A first cylinder group of the internal combustion engine is assigned a first exhaust gas train and a second cylinder group of the internal combustion engine is assigned a second exhaust gas train, each exhaust gas train comprising at least one exhaust gas purification device arranged downstream of the respective cylinder group. Rear silencers are arranged downstream of the respective exhaust gas purification device.

The subsequently published ones DE 10 2009 032 215 A1 and DE 10 2009 037 285 A1 reveal further exhaust systems from internal combustion engines.

Based on this, the present invention is based on the object of creating a new type of exhaust system for an internal combustion engine with improved exhaust gas purification.

This object is achieved by an exhaust system of an internal combustion engine according to claim 1. According to the invention, each exhaust system of the exhaust system comprises: a NOx storage catalytic converter arranged downstream of the respective silencer; a bypass line via which exhaust gas from the respective exhaust gas purification device can be fed to the respective NOx storage catalytic converter, bypassing the respective silencer; and a shut-off device connected between the respective exhaust gas purification device and the respective silencer, which is closed or opened depending on an operating point in which the exhaust system and/or the internal combustion engine is operated.

The exhaust system according to the invention allows more effective, improved exhaust gas purification. In particular, it is possible to operate NOx storage catalysts, which are also referred to as DeNOx catalysts, in an optimal temperature range, which, on the one hand, improves exhaust gas purification and, on the other hand, increases the service life of the temperature-sensitive NOx storage catalysts.

According to an advantageous further development of the invention, each exhaust line comprises a further bypass line, via which exhaust gas can be discharged into the environment via at least one exhaust tailpipe, bypassing the NOx storage catalytic converter of the respective exhaust line. This makes it possible to further improve exhaust gas purification and increase the service life of the temperature-sensitive NOx storage catalytic converters, since the optimal temperature range for operating the NOx storage catalytic converters can be better maintained.

The bypass lines, via which exhaust gas from the respective exhaust gas purification device can be fed to the respective NOx storage catalytic converter while bypassing the silencer, preferably have a smaller flow cross section than other exhaust gas-carrying lines. This also makes it possible to further improve exhaust gas purification and increase the service life of the temperature-sensitive NOx storage catalytic converters, since the optimal temperature range for operating the NOx storage catalytic converters can be better maintained.

• 1 eine schematisierte Darstellung eines ersten Ausführungsbeispiels einer erfindungsgemäßen Abgasanlage einer Brennkraftmaschine;
• 2 eine schematisierte Darstellung eines zweiten Ausführungsbeispiels einer erfindungsgemäßen Abgasanlage; und
• 3 eine schematisierte Darstellung eines dritten Ausführungsbeispiels einer erfindungsgemäßen Abgasanlage.

Preferred developments of the invention result from the subclaims and the following description. Exemplary embodiments of the invention are explained in more detail using the drawing, without being limited to this. This shows:

• 1 a schematic representation of a first exemplary embodiment of an exhaust system according to the invention of an internal combustion engine;
• 2 a schematic representation of a second embodiment of an exhaust system according to the invention; and
• 3 a schematic representation of a third embodiment of an exhaust system according to the invention.

1 shows a diagram of an exhaust system 10 according to the invention of an internal combustion engine with two cylinder groups 11, 12 according to a first exemplary embodiment of the present invention.

Each cylinder group 11, 12 of the internal combustion engine is assigned an exhaust system 13, 14 of the exhaust system 10, namely the cylinder group 11 is the exhaust system 13 and the cylinder group 12 is the exhaust system 14.

Each exhaust line 13 or 14 comprises an exhaust gas purification device 15 or 16, a silencer 17 or 18 downstream of the respective exhaust gas purification device 15 or 16 and a NOx storage catalytic converter 19 or 20 downstream of the respective silencer 17 or 18. NOx storage catalytic converters become also known as DeNOx catalysts.

In the exemplary embodiment 1 The exhaust devices 15 and 16, which are positioned in each exhaust system 13, 14 between the respective cylinder group 11 and 12 and the respective silencer 17 and 18, are 3-way catalytic converters, with the exhaust gas from each cylinder group 11 or 12 is supplied to the respective exhaust gas purification device 15 or 16 via an inlet funnel 21 or 22 of the same and exhaust gas cleaned at the respective exhaust gas purification device 15, 16 leaves the respective exhaust gas purification device 15, 16 via an outlet funnel 23 or 24 of the same.

Exhaust gas emerging from the exhaust gas purification devices 15, 16 can enter the respective silencer 17 or 18 in the area of each exhaust line 13, 14, in the exemplary embodiment 1 each of the silencers 17, 18 comprises an entry area 25 and 26 and two exit areas 27 and 28, respectively. Exhaust gas emerging from the silencer 17 and 18 via the exit areas 27 and 28 can be conveyed in the direction of the NOx storage catalytic converters of the respective exhaust system 13, 14.

Each exhaust line 13, 14 in the 1 The exhaust gas purification system 10 shown also has a bypass line 29 or 30, wherein exhaust gas can be fed to the respective NOx storage catalytic converter 19 or 20 of the respective exhaust gas line 13 or 14 via the respective bypass line 29 or 30, bypassing the respective silencer 17 or 18 .

Each exhaust line 13, 14 of the exhaust system 10 also has a shut-off device 31 or 32, which is connected between the respective exhaust gas purification system 15, 16 of the respective exhaust line 13, 14 and the respective silencer 17, 18 of the same, the shut-off devices 31, 32 being dependent are closed or opened from an operating point in which the exhaust system 10 and/or the internal combustion engine is operated.

Preferably, each NOx storage catalytic converter 19, 20 is assigned a temperature sensor 33 or 34, which in the exemplary embodiment shown is located upstream of the respective NOx storage catalytic converter and detects a temperature of the exhaust gas immediately in front of the respective NOx storage catalytic converter 19, 20, the above shut-off devices 31 , 32 are closed or opened depending on a measured value that the respective temperature sensor 33 or 34 provides.

In the preferred exemplary embodiment shown, each of the NOx storage catalysts 19, 20 is assigned to a further silencer 35 or 36, with the NOx storage catalyst 19, 20 of the respective exhaust system 13 or 14 receiving exhaust gas via an individual silencer prechamber 37 or 38 of the respective further one Silencer 35 or 36 can be supplied. In the exemplary embodiment 2 the exhaust gas flowing through the two NOx storage catalytic converters 19, 20 flows into a common silencer afterchamber 39, and can be discharged into the environment from the common silencer afterchamber 39 via a common exhaust tailpipe 40.

According to 1 In addition to the already mentioned bypass line 29, 30, each exhaust line 13, 14 has a further bypass line 41 or 42, via which exhaust gas is fed into the exhaust line via an exhaust tailpipe 43, bypassing the respective NOx storage catalytic converter 19 or 20 of the respective exhaust line 13, 14 Environment can be derived, with this exhaust tailpipe 43 being assigned a further shut-off device 44. The further bypass lines 41 and 42 of the exhaust gas lines 13 and 14 branch off from the respective silencer antechamber 37 and 38 of the respective further silencer 35, 36, bypassing the respective NOx storage catalytic converter 19, 20.

The shut-off device 44 integrated into the exhaust tailpipe 43, like the shut-off devices 31, 32, is closed or opened depending on the operating point at which the exhaust system 10 and/or the internal combustion engine is operated, preferably depending on the measured values of the temperature sensors 33, 34.

In addition to the assemblies mentioned above, in 1 NOx sensors 45 and lambda sensors 46 are shown, with the help of which the operation of the exhaust system 10 can be controlled or regulated.

As already mentioned, the NOx storage catalysts 19 and 20 are temperature-sensitive assemblies that are intended to be operated in an optimal temperature range to ensure good cleaning quality for the exhaust gas and to ensure a long service life of the NOx storage catalysts 19, 20.

In order to ensure this, the respective shut-off device 31, 32 and the shut-off device 44 are closed in the area of both exhaust gas lines 13 and 14, in particular during a so-called cold start of the exhaust system or the internal combustion engine, with exhaust gas then flowing out from the exhaust gas cleaning devices 15, 16 via the Bypass lines 29, 30 can be supplied directly and via the shortest route to the NOx storage catalysts 19, 20 in order to achieve the same as possible to quickly heat to an optimal operating temperature.

This preferably takes place depending on the measured value that the temperature sensors 33, 34 provide, whereby if the measured value provided by the temperature sensors 33, 34 is smaller than a first limit value, the shut-off devices 31, 32 and 44 are all closed, whereas then, If the measured values recorded by the temperature sensors 33, 34 are greater than this first limit value, only the shut-off device 44 is closed, whereas the shut-off devices 31 and 32 are open. This first limit value is preferably 250 ° C, but can also take on a different value.

Then, when the temperature detected by the temperature sensors 33, 34 is greater than a second limit value, which is above the first limit value, the shut-off device 44, which is assigned to the further bypass lines 41, 42, is additionally opened in order to prevent this the NOx storage catalysts 19, 20 are heated to an impermissibly high temperature. This second temperature limit is in particular 750 ° C, but can also take on a different value.

If the temperature detected by the temperature sensors 33, 34 is smaller than the first limit value, all shut-off devices 31, 32 and 44 are closed. In this case, the NOx storage catalysts 19, 20 are then heated quickly.

However, if the temperature detected by the temperature sensors 33, 34 is greater than the second limit value, the shut-off devices 31, 32 and 44 are all open in order to avoid further heating of the NOx storage catalytic converters 19, 20. Then, when the temperature detected by the temperature sensors 33, 34 is between the first limit value and the second limit value, the shut-off devices 31 and 32 are open, but the shut-off device 44 is closed.

The bypass lines 29, 30 preferably have smaller cross sections than the other exhaust gas-carrying lines of the exhaust system 10. This is important in order to prevent the exhaust gas from cooling in the area of the bypass lines 29, 30 as much as possible during the cold start already mentioned, so that ultimately the NOx -Storage catalysts 19, 20 can be heated quickly to a temperature in the preferred, optimal temperature range.

Another exemplary embodiment of an exhaust system 47 according to the invention shows 2 , where in 2 The same reference numbers are used for the same assemblies as in the exemplary embodiment 1 , and only those details will be discussed below that make the exemplary embodiment of the 2 from the exemplary embodiment of 1 differs.

In the exemplary embodiment of 1 The exhaust gas purification devices 15, 16 of the two exhaust gas lines 13, 14 are each a 3-way catalytic converter in the form of in-line catalytic converters. In the exemplary embodiment 2 Two 3-way catalytic converters are used as exhaust gas purification devices 15a, 15b or 16a, 16b for each exhaust line 13, 14, according to 2 the exhaust gas purification devices or 3-way catalytic converters 15a, 15b and 16a, 16b connected in parallel have a common inlet funnel 21 and 22 but separate outlet funnels 23 and 24.

Another difference between the exhaust system 10 of the exemplary embodiment 1 and the exhaust system 47 of the exemplary embodiment 2 is that in the area of the silencers 17, 18 there are two entry areas 25 and 26, but only one exit area 27 and 28 is formed.

A shut-off device 31a, 31b and 32a, 32b is positioned between the exhaust gas purification devices 15a, 15b and 16a, 16b of the respective exhaust gas lines 13 and 14 and the respective inlet areas 25 and 26 of the respective silencers 17 and 18, which in turn are in accordance with the Embodiment of the 1 are opened or closed depending on the operating point of the exhaust system and / or internal combustion engine, in particular depending on the temperature detected by the temperature sensors 33, 34.

In the exemplary embodiment 2 If the temperature detected by temperature sensors 33, 34 is less than a first limit value, all shut-off devices 31a, 31b, 32a, 32b and 44 are closed. If the temperature detected by the temperature sensors 33, 34 is greater than a second limit value that is above the first limit value, all shut-off devices 31a, 31b, 32a, 32b and 44 are open. However, if the measured value recorded by the temperature sensors 33, 34 is between the first, lower limit value and the second, upper limit value, then the shut-off devices 31a, 32a and 44 are preferably closed, whereas the shut-off devices 31b and 32b are open.

A further exemplary embodiment of an exhaust system 48 according to the invention based on the exemplary embodiment of 2 shows 3 , whereby the exemplary embodiment of the 3 from the exemplary embodiment of 2 differs in that each NOx storage catalytic converter 19, 20 is assigned a separate silencer chamber 39, so that starting from each silencer chamber 39, exhaust gas can then be discharged into the environment via a separate exhaust tailpipe 40.

Furthermore, according to 3 Each of the bypass lines 41 and 42 is assigned a separate shut-off device 44, with separate exhaust tailpipes 43 also being formed in the area of the bypass lines 41, 42.

Other variations of exhaust systems are conceivable. So can also in the exemplary embodiment 3 instead of the parallel catalysts 15a, 15b and 16a, 16b, the series catalysts 15, 16 1 are used.

Furthermore, in the exemplary embodiment the 1 separate silencer chambers 39 with separate exhaust tailpipes 40, 43 may be present.

Even if separate silencer chambers 39 with separate exhaust tailpipes 40 are present, the bypass lines 41 and 42 can open into a common exhaust tailpipe 43.

A further variation of the invention can be seen in the fact that the shut-off devices 31, 32 and 44 or 31a, 31b, 32a, 32b and 44 are not only opened and closed depending on the temperatures detected by the temperature sensors 33, 34, but also depending on the load condition and/or the speed of the internal combustion engine.

For example, it is possible that when the internal combustion engine is operated under full load, all shut-off devices 31, 32, 44 or 31a, 31b, 32a, 32b and 44 are open, preferably when in combination with the full load The temperatures detected by the temperature sensors 33, 34 are greater than a defined limit value.

If the exhaust system according to the invention is used in an internal combustion engine with turbochargers, a turbocharger is preferably positioned between the cylinder groups 11, 12 and the silencers 17, 18 for each exhaust system. In this case, the exhaust gas purification devices 15, 16 or 15a, 15b, 16a, 16b can be relocated to the area of the further silencers 35, 36.

Reference symbol list

10

Exhaust system

11

Cylinder group

12

Cylinder group

13

Exhaust system

14

Exhaust system

15

Exhaust gas purification device

15a

Exhaust gas purification device

15b

Exhaust gas purification device

16

Exhaust gas purification device

16a

Exhaust gas purification device

16b

Exhaust gas purification device

17

silencer

18

silencer

19

NOx storage catalytic converter

20

NOx storage catalytic converter

21

Inlet funnel

22

Inlet funnel

23

discharge funnel

24

discharge funnel

25

Entry area

26

Entry area

27

Exit area

28

Exit area

29

Bypass line

30

Bypass line

31

Shut-off device

31a

Shut-off device

31b

Shut-off device

32

Shut-off device

32a

Shut-off device

32b

Shut-off device

33

Temperature sensor

34

Temperature sensor

35

another silencer

36

another silencer

37

Silencer prechamber

38

Silencer prechamber

39

Silencer chamber

40

Exhaust tailpipe

41

another bypass line

42

another bypass line

43

Exhaust tailpipe

44

Shut-off device

45

NOx sensor

46

Lambda probe

47

Exhaust system

48

Exhaust system

Claims (9)

Exhaust system (10) of an internal combustion engine, with a first exhaust line (13) assigned to a first cylinder group (11) of the internal combustion engine and with a second exhaust line (14) assigned to a second cylinder group (12) of the internal combustion engine, each exhaust line (13, 14) being at least an exhaust gas purification device (15, 16; 15a, 15b; 16a, 16b) downstream of the respective cylinder group and at least one silencer (17, 18) downstream of the respective exhaust gas purification device (15, 16; 15a, 15b; 16a, 16b), characterized in that that each exhaust line (13, 14) comprises a NOx storage catalytic converter (19, 20) arranged downstream of the respective silencer (17, 18); each exhaust line (13, 14) comprises a bypass line (29, 30) via which exhaust gas from the respective exhaust gas purification device (15, 16; 15a, 15b; 16a, 16b) is delivered to the respective NOx, bypassing the respective silencer (17, 18). Storage catalytic converter (19, 20) can be supplied; each exhaust line (13, 14) comprises a shut-off device (31, 32; 31a, 31b, 32a, 32b) connected between the respective exhaust gas purification device (15, 16; 15a, 15b, 16a, 16b) and the respective silencer (17, 18). which is closed or opened depending on an operating point in which the exhaust system (10) and/or the internal combustion engine is operated. Exhaust system (10). Claim 1 , characterized in that each exhaust line (13, 14) has a temperature sensor (33, 34) assigned to the respective NOx storage catalytic converter (19, 20), the respective shut-off device (31, 32; 31a, 31b, 32a, 32b) of respective exhaust system is closed or opened depending on a measured value of the respective temperature sensor (33, 34). Exhaust system (10). Claim 1 or 2 , characterized in that the bypass lines (29, 30), via which exhaust gas from the respective exhaust gas purification device (15, 16; 15a, 15b; 16a, 16b) is fed to the respective NOx storage catalytic converter (19, 20) can be supplied, have a smaller flow cross section than other exhaust gas lines. Exhaust system (10) according to one of the Claims 1 until 3 , characterized in that each exhaust line (13, 14) comprises a further bypass line (41, 42), via which exhaust gas can be discharged into the environment via at least one exhaust tailpipe (43), bypassing the NOx storage catalytic converter (19, 20) of the respective exhaust line is. Exhaust system (10). Claim 4 , characterized in that the further bypass lines (41, 42) are each assigned one or a common further shut-off device (44), which is closed or opened depending on the operating point at which the exhaust system (10) and / or the internal combustion engine is operated is. Exhaust system (10). Claim 5 , characterized in that the or each further shut-off device (44) is also closed or opened depending on a measured value from a temperature sensor (33, 34). Exhaust system (10) according to one of the Claims 4 until 6 , characterized in that the NOx storage catalytic converter (19, 20) of each exhaust line (13, 14) is positioned in a further silencer (35, 36), such that each NOx storage catalytic converter (19, 20) of each exhaust line ( 13, 14) is assigned an individual silencer pre-chamber (37, 38), the further bypass lines (41, 42) branching off from these silencer pre-chambers. Exhaust system (10). Claim 7 , characterized in that each NOx storage catalytic converter (19, 20) of each exhaust line (13, 14) is assigned an individual silencer after-chamber (39), with an individual exhaust tailpipe (40) preferably opening into the environment from each individual silencer after-chamber (39). Exhaust system (10). Claim 7 , characterized in that the NOx storage catalysts (19, 20) of the exhaust lines (13, 14) are assigned a common silencer chamber (39), from which a common exhaust tailpipe (40) preferably opens into the environment.

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