WO2005093229A2

WO2005093229A2 - Exhaust system for an internal combustion engine

Info

Publication number: WO2005093229A2
Application number: PCT/AT2005/000093
Authority: WO
Inventors: Paul Kapus; Thomas Cartus
Original assignee: Avl List Gmbh
Priority date: 2004-03-25
Filing date: 2005-03-17
Publication date: 2005-10-06
Also published as: DE112005000653A5; WO2005093229A3

Abstract

The invention relates to an exhaust system (1), for an internal combustion engine, comprising at least two groups (3, 4) of cylinders (2), whereby each group (3, 4) is provided with a partial exhaust line (5, 6; 12, 13) and the inlet sides of the exhaust lines (5, 6) run separately to a common catalyst housing (7) with a single catalyst block (8). The inlet sides of the exhaust lines (5, 6) run separately to an inlet front face (9) of the catalyst block (8), such that each exhaust line (5, 6) affects a given inlet region (14, 15) of the inlet front face (9) of the catalyst block (8). According to the invention, the service life of the catalyst may be increased and fractures avoided, whereby the inlet regions (14, 15) and/or outlet regions (16, 17) of the catalyst block (8), for different partial exhaust lines (5, 6; 12, 13), are arranged essentially concentric to each other.

Description

Exhaust system for an internal combustion engine

The invention relates to an exhaust system for an internal combustion engine with at least two groups of cylinders, with each group being assigned a partial exhaust gas train and the inlet-side partial exhaust gas strands being routed separately to a common catalyst housing with a single catalyst brick, the inlet-side partial exhaust gas string being separated up to an inlet end of the catalyst brick are guided so that each exhaust gas strand acts on a predefined inlet area of the inlet end of the catalyst brick.

Furthermore, the invention relates to an exhaust system for an internal combustion engine with at least one exhaust aftertreatment system having at least one first particle filter in the exhaust line, wherein at least one second particle filter is arranged downstream of the first particle filter in the exhaust line and at least one first sensor and between the first and second particle filter upstream of the first particle filter at least one second sensor is arranged.

In order to use and maintain the gas dynamic activity of the exhaust system of a multi-cylinder internal combustion engine, the exhaust lines are grouped together and subjected to exhaust aftertreatment separately in groups. A mutual interference of the gas dynamic activity can thereby be avoided.

From EP 0 852 289 AI it is known to arrange a catalyst in each group of partial exhaust gas strands. Furthermore, it is also known from this publication to arrange the catalysts of both groups concentrically to one another in a single catalyst housing, the exhaust gas of one group flowing through a central cylindrical catalyst and the exhaust gas of the second group flowing through a ring catalyst. After the catalytic converter arrangement, the exhaust gases from both groups leave the catalytic converter housing through a common exhaust pipe. Since a catalytic converter is required for each partial exhaust gas train, this exhaust system is, however, relatively expensive.

DE 92 01 320 U1 discloses a catalytic converter device for internal combustion engines, with at least two exhaust gas inlet pipes and at least two gas outlet pipes that can be connected to the internal combustion engine and at least two gas outlet pipes connected to the housing surrounding the catalyst substrate, the cross-sectional areas of which on the inlet and outlet sides are opposite different areas of the associated substrate end faces. No. 5,950,423 A describes an exhaust gas system with a catalytic converter arrangement, into which two exhaust gas lines open concentrically. In one embodiment, a funnel-shaped exhaust gas distribution device is arranged downstream of the catalytic converter. The partial exhaust gas strands are therefore not continued separately downstream of the catalytic converter, but are combined immediately downstream of the catalytic converter and before they enter a further exhaust gas aftertreatment device. However, an early combination of the exhaust gas flows has a disadvantageous effect on the gas dynamic activities.

It is also known to feed the exhaust gas branch of two groups of cylinders to a common catalyst housing containing a single catalyst brick, the exhaust gas of each group acting on one half of the catalyst brick. The exhaust gas from the two groups is separated by a partition up to the inlet end of the catalyst brick, a predefined gap being provided between the partition and the inlet end of the catalyst brick. Due to the different pressures in the exhaust gas lines, however, there is a lateral load on the catalyst brick, which can cause cracks and breaks in the catalyst brick.

It is known to use particle filter systems, in particular in diesel internal combustion engines, to increase the exhaust gas quality. The particle filters are regenerated from a certain soot load, whereby the soot burn-up means that the particle filter is exposed to higher temperatures for a short time. This leads to thermal stresses in the filter substrate, which can lead to hairline cracks, which reduce the efficiency of the particle filter. The filter substrates of particle filter systems mostly consist of silicon carbide or Korderiete ceramics with a honeycomb structure. Such systems have filter efficiencies for the insoluble particle fraction between 90% and 99%. With these high levels of efficiency, the current legal limits for car certification can be reached and even undercut by an order of magnitude. This means that if the macrostructure is damaged, such as hairline cracks, which typically occur during the legally required service life of 120,000 km of a particle filter, the efficiency is adversely affected, but compliance with the limit values is nevertheless guaranteed. This situation changes when the limit values are reduced by an order of magnitude in future exhaust gas regulations. With the particle filter systems currently in use, permanent compliance with the limit values can then no longer be guaranteed.

It is known to connect an oxidation catalytic converter upstream of the particle filter in order to increase the efficiency of the soot filter. The upstream of the particle filter dation catalyst oxidizes NO to NO ₂ . NO ₂ in turn oxidizes the soot, which consists mainly of carbon, to CO ₂ .

An exhaust system is known from JP 60-043113 A, in which a particle filter is arranged downstream of a catalytic converter. Particle filter and catalytic converter are each housed in their own housing.

EP 0 405 310 A2 discloses an exhaust system with an oxidation catalyst, which is connected upstream of the soot filter. Oxidation catalyst and particle filter are arranged in a common housing.

EP 0 154 145 A2 describes a device for cleaning the exhaust gases of diesel engines with filter elements arranged one behind the other for the separation of soot particles, at least one filter element carrying a catalyst which lowers the ignition temperature of the soot and promotes its combustion, and at least one filter element carries the gaseous combustion Catalyst promoting pollutants carries, the filter elements with different catalysts alternate several times. Particle filters of this type with a catalytic coating are, however, more expensive than particle filters which are connected downstream of a catalytic converter for exhaust gas aftertreatment.

Furthermore, from DE 32 03 237 AI an exhaust gas filter for internal combustion engines with a filter insert is known, which consists of a plurality of compressed, axially arranged wire mesh disks, which are surrounded by metallic enclosures of various designs, the adjoining enclosures being welded to one another. The soot retention capacity and thus the efficiency are, however, worse than with standard particle filter systems made of filter substrates, which consist of SiC or Korderiete ceramics.

FR 2 795 132 AI discloses an exhaust system for an internal combustion engine with two particle filters arranged one behind the other in a housing. The second particle filter downstream of the first particle filter is dimensioned smaller than the first. Pressure sensors are arranged in front of the first particle filter and between the two particle filters in order to determine the pressure drop of the first particle filter. As a result, the pressure changes occurring in the event of a filter break can be measured before the first particle filter and between the particle filters and appropriate conclusions can be drawn. However, it is not possible to evaluate the second particle filter or each particle filter for itself.

Exhaust systems with particle filters arranged one behind the other are also known from DE 199 23 781 AI and US 4,887,427 A. The object of the invention is to avoid these disadvantages and to increase the service life of the catalyst in an exhaust system of the type mentioned.

Another object of the invention is to ensure permanent compliance with legal limit values.

According to the invention, this is achieved in that the inlet areas and / or outlet areas of the catalyst brick of different exhaust gas partial strands are arranged essentially concentrically to one another and that each outlet area is designed to be flush with an inlet area of the corresponding inlet-side partial exhaust gas strand. It is preferably provided that an inlet-side first exhaust gas partial strand is guided in the region of the entry into the catalyst brick within a region of an inlet-side second exhaust gas strand preferably formed by an inlet cone. The inlet-side first exhaust gas strand can be inserted into the inlet cone of the inlet-side second exhaust gas strand and welded to it. As an alternative to this, it can be provided that the inlet cone is designed as a cast piece, the inlet cone preferably having a preferably conical inner tube associated with the inlet-side first exhaust gas partial section. Analogously to this, it can further be provided that an outlet-side first exhaust gas strand is guided in the area of the outlet from the catalyst brick within a region of an outlet-side second exhaust gas strand which is preferably formed by an outlet cone, the outlet-side first exhaust gas strand preferably being led into the outlet cone of the outlet-side second tube Exhaust gas strand inserted and welded to it. As an alternative to this, it can be provided that the outlet cone is designed as a cast piece, the outlet cone preferably having a preferably conical inner tube associated with the outlet-side first exhaust gas partial line. The preferably conical inner tube can each be made in one or more parts with the inlet or outlet cone.

A predefined gap is formed between the inlet and the outlet-side first exhaust gas strands and the catalyst brick in order to avoid mechanical stresses in the catalyst brick. In the area of the gaps, a sealing means can be provided between the first partial exhaust gas strands and the catalyst brick in order to separate the first partial exhaust gas strand from the second partial exhaust gas strand. The sealing means can be designed as a labyrinth seal, with a step or groove formed by shaping the catalyst brick particularly preferably improving the sealing of the preferably conical inner tube with respect to the second partial exhaust gas line. The sealant can also be formed as a soft material seal. In a particularly advantageous embodiment variant, it is provided that a λ probe is arranged in the region of the gap in such a way that the exhaust gas flows from all groups of cylinders can be monitored with this λ probe. To accommodate the λ probe, the sealant preferably has at least one material breakthrough. In addition to a λ probe in the area of the entry face, a second λ probe can be arranged in the area of the exit face for diagnostic purposes. Alternatively, it can be provided that at least one λ-probe is arranged in the area of the inlet or outlet cone or in the area of the entry or exit of the first partial exhaust line into or out of the second partial exhaust line such that the exhaust gas flows of both partial exhaust lines are monitored can. It can be provided that the λ probe borders on a flow connection between the first and second partial exhaust gas strands. The cross-section of the flow connection is so small that the gas dynamic activity is not or hardly influenced. The fact that each λ probe can recognize the exhaust gas lines of both groups means that the number of λ probes can be significantly reduced.

The catalyst brick can be made of ceramic.

Permanent compliance with legal limit values can be ensured by arranging at least one third sensor downstream of the second particle filter. The third sensor can be used to separately evaluate each individual particle filter. It is therefore not only possible to immediately detect defects in the first, but also in the second particle filter. The third sensor can be designed to be temperature-sensitive and / or pressure-sensitive. In particular, a pressure sensor can be used to immediately detect unusual pressure drops at the second particle filter. However, it is also possible to design at least one sensor as an acoustic or photoacoustic sensor. At least one oxidation catalyst can be arranged upstream of the first particle filter. The oxidation catalyst increases the efficiency of the particle filter.

The first and second particle filters can thus be arranged in series one behind the other. The dimensioning of the larger first particle filter, which is arranged first in the flow direction, is such that operation is possible without restriction, that is to say the design of the loading and regeneration strategy is based on this first particle filter. Immediately after this first particle filter, the significantly smaller second particle filter is connected in series. This second particle filter increases the filter efficiency in normal operation and ensures the necessary filter effect of the entire system if the first particle filter is damaged. Since this second particle filter has a significantly lower load compared to the upstream first particle filter, the demand is on Regeneration significantly less. In addition, due to the arrangement, the second particle filter is located immediately after the first particle filter during the regeneration in the hot exhaust gas stream, so that soot burn-off in the second particle filter is ensured. Due to the lower soot loading of the second particle filter, temperature peaks, which typically occur during filter regeneration due to the soot burn-off, are avoided.

At least one particle filter has a particle filter structure with filter channels. Due to the particle filter structure, the exhaust gas has to pass the wall between adjacent filter channels.

The particle filters advantageously consist of filter substrates, preferably of sintered metal, silicon carbide, cord rivets or similar ceramics, with at least one particle filter having a catalytic coating to increase the efficiency.

At least two components from the group consisting of an oxidation catalyst, a first particle filter and a second particle filter can be arranged in a common housing. Alternatively, it is also possible to accommodate the components in separate housings. The first and second particle filters are spaced apart in the flow direction in order to compensate for thermal stresses.

The second particle filter is thus less loaded, so damage to the second particle filter is less likely. If an error occurs in the second particle filter, it can be detected immediately via the third sensor.

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

1 shows a known exhaust system;

2 shows an exhaust system according to the invention;

FIG. 3 shows detail III of this exhaust system from FIG. 2;

4 shows detail III in an embodiment variant;

5 shows the detail V from FIG. 3 in a first embodiment variant;

6 shows the detail V from FIG. 3 in a second embodiment variant;

7 shows the detail V from FIG. 3 in a third embodiment variant;

8 shows the detail V from FIG. 3 in a fourth embodiment variant; and 9 shows an exhaust gas aftertreatment device arranged in an exhaust line of an internal combustion engine.

1 shows a known exhaust system 21 with a plurality of cylinders 22. Each exhaust group 23, 24 of cylinders 22 is assigned a partial exhaust line 25, 26. The two exhaust gas strands 25, 26 are guided separately to a catalyst housing 27 common to both exhaust gas strands 25, 26, in which a single catalyst brick 28 is arranged. The two partial exhaust gas strands 25, 26 end immediately in front of an inlet end 29 of the catalyst brick 28, a partition 30 being guided between the two partial exhaust gas strands 25, 26 until just before the catalyst brick 28, but not touching it. Exhaust partial strands 32, 33 are connected to the outlet end 31 of the catalyst brick 28, the inlet regions 34; 35 of the entry face 29 and the exit areas 36; 37 of the outlet end face 31 of the catalyst brick 28 are arranged in alignment with one another in the flow direction, so that each half of the catalyst brick 28 is only flowed through by exhaust gas from a group 23, 24 of cylinders 22. Due to the different pressures in the exhaust gas strands 25, 26, however, there is a lateral load on the catalyst brick 28, which can lead to breaks and jumps within the catalyst brick 28.

FIGS. 2 and 3 show an exhaust system 1 according to the invention for an internal combustion engine with a plurality of cylinders 2, which are combined into two groups 3, 4 in terms of exhaust gas. The exhaust gas from the first group 3 is combined in a first exhaust sub-branch 5, the exhaust gas from the second group 4 in a second exhaust sub-branch 6. The two exhaust gas strands 5, 6 are led separately to a common catalyst housing 7, in which a single catalyst brick 8 is arranged. The two partial exhaust gas strands 5, 6 on the inlet side are routed separately up to just in front of the inlet end face 9 of the catalyst brick 8. Two separate exhaust-side partial strands 12, 13 connect to the outlet end 11 of the catalyst brick 8. The inlet areas 14, 15 and the outlet areas 16, 17 of the first and second exhaust gas strands 5, 12; 6, 13 are designed in alignment with one another in the flow direction, so that the exhaust gas of the two groups 3, 4 flows through the catalyst brick 8 in different areas thereof.

It is essential that the inlet regions 14, 15 of the inlet end face 9 are arranged concentrically with respect to the longitudinal axis 8a of the catalyst brick 8. It is just as important that the outlet regions 16, 17 of the outlet end face 11 are formed concentrically to the longitudinal axis 8a of the catalyst brick 8. It is thereby achieved that the exhaust gas of the first exhaust gas strand 5 only has the catalyst brick 8 in a core area, and the exhaust gas of the second exhaust gas strand 5 6 flows through the catalyst brick 8 in an annular peripheral region 19 surrounding the core region 18. The catalyst brick 8 is thus evenly radially loaded by the different pressures in the exhaust lines 5, 6, whereby breaks can be largely avoided. Since the pressure pulsations of the two exhaust gas strands 5, 6 in the catalyst brick 8 only act radially from the inside to the outside or from the outside to the inside, there is no damage to the catalyst brick 8. Another advantage of this arrangement is that the heat is released to the environment can be kept very low and the heating time of the catalyst can be reduced.

As can be seen from FIGS. 2 and 3, the partial exhaust gas strands 5, 6, 12, 13 are arranged in a tube-in-tube construction in the region of the entry and the exit into or out of the catalyst housing 27, the conical tube 5a of the first exhaust line 5 is inserted and welded into an inlet cone 6a of the second exhaust line 6 on the inlet side. The outlet-side first exhaust gas strand 12 is also inserted into an outlet cone 13a of the outlet-side second exhaust gas strand 13 and welded to it. Alternatively, the inlet and outlet cones 6a, 13a can be designed as castings, the inner tubes 5a, 12a being made in one or more parts with the inlet and outlet cones 6a, 13a. The inner tubes 5a, 12a of the inlet and outlet-side first exhaust gas strand 5 or 12 reach the catalyst brick 8 up to a short distance and are therefore not directly connected to it. In the area of the gap s formed in this way between the inner tube 5a, 12a of the first partial exhaust gas line 5, 12, a λ probe 20a, 20b is arranged in such a way that the air ratio of the exhaust gas of both partial exhaust gas lines 5, 6 can be determined with this. As an alternative to this, the λ-probe 20a, 20b can be arranged in the area of the inlet 26a or in the area of the outlet 26b of the first partial exhaust line 5, 12 in or out of the second partial exhaust line 6, 13 such that the exhaust gas flows of both partial exhaust lines 5, 6 ; 12, 13 can be monitored. The λ probe 20a, 20b protrudes into a flow connection 27 between the first and second partial exhaust gas strands 5, 6; 12, 13, which is so small that there is little crosstalk and the gas dynamic activity is not disturbed. The λ probe 20b is used, for example, for diagnostic purposes.

In order to obtain the highest possible gas dynamic activities, in the area of the gap s between the inner tube 5a, 12a and the catalyst brick 8, a sealing device 21 for sealing the first from the second exhaust gas strand 5, 6; 12, 13 may be provided. The sealing device 21 can be formed by a labyrinth seal 22, which is formed by at least one concentric step 23 (FIG. 4, FIG. 5) or annular groove formed on the catalyst brick 8 24 (Fig. 6, Fig. 7) is designed. The stage 23 can either in the first or in the second partial exhaust gas stream 5, 6; 12, 13 protruding. In addition, a soft material seal 25 can be provided, which is inserted into the groove 24 in FIG. 7.

In this way, double-flow exhaust gas control with four λ probes can be avoided. Thus, only two λ probes 20a, 20b are necessary, which significantly reduces the construction and control engineering effort.

FIG. 9 schematically shows an exhaust gas aftertreatment device 103 arranged in an exhaust line 101 of an exhaust system 102, which has an oxidation catalyst 104, a first particle filter 105 and a second particle filter 106, wherein oxidation catalyst 104, first particle filter 105 and second particle filter 106 are arranged one behind the other in flow direction 108 are.

In the exemplary embodiment shown, oxidation catalytic converter 104, first particle filter 105 and second particle filter 106 are arranged in a common housing 107. However, it is also possible to accommodate the three components in common housings.

The first particle filter 105 arranged first in the direction of flow 108 is dimensioned such that operation is possible without restriction. The design of the loading and regeneration strategy is based on this first particle filter 105. Immediately after the first particle filter 105, but at a slight distance from it, the second particle filter 106 is provided, which is designed to be significantly smaller than the first particle filter 105. This second particle filter 106 increases the filter efficiency in normal operation and, if the first particle filter 105 is damaged, ensures the necessary filter effect of the entire exhaust gas aftertreatment system 103. Since this second particle filter 106 is loaded significantly less than the first particle filter 105, the need for regeneration is significantly less. During the regeneration of the first particle filter 105, hot exhaust gases also flow through the second particle filter 106, so that soot burn-off is also ensured in the second particle filter 106. The lower soot loading of the second particle filter 106 avoids temperature peaks which could typically occur during the filter regeneration due to the soot burn-off. However, these temperature peaks are the cause of thermal stresses, which in turn lead to hairline cracks in the filter material. Since the second particle filter 106 is loaded much less, damage to the second particle filter 106 is less likely. This can ensure that even with higher mileage A sufficiently high filter effect is maintained so that the legal requirements can be met with a high degree of certainty.

In principle, the first and second particle filters 105, 106 can also be arranged in separate housings 107. However, the arrangement in a single housing 107 has the advantage that a sufficiently high soot burn-up takes place in the second particle filter 106 when the first particle filter 105 is regenerated. The state of the first particle filter 105 can be monitored by means of a pressure-sensitive first sensor 109 and a pressure-sensitive second sensor 110 via an electronic control unit 112 by determining the pressure difference. Sudden drop in pressure indicates a filter break. This makes it possible to take measures immediately after damage has occurred. A first pressure sensor 109 can also be placed in front of the oxidation catalytic converter 104, as is indicated by the dashed line.

It is particularly advantageous if a pressure- or temperature-sensitive third sensor 111 is arranged downstream of the second particle filter 106. As a result, filter breaks in the second particle filter can also be detected at an early stage. Furthermore, the third sensor 111 can replace the second sensor 110 or can be used to monitor the second sensor 110. In the event of a malfunction or failure of the second sensor 110, particle filter breaks can still be determined with the aid of the third sensor 111, but cannot be localized exactly.

Claims

PATENT CLAIMS

1. Exhaust system (1) for an internal combustion engine with at least two groups (3, 4) of cylinders (2), each group (3, 4) being assigned a partial exhaust gas line (5, 6; 12, 13) and the partial exhaust line on the inlet side ( 5, 6) are routed separately to a common catalytic converter housing (7) with a single catalytic converter brick (8), the partial exhaust gas strands (5, 6) on the inlet side being routed separately up to an inlet end face (9) of the catalytic converter brick (8), so that Each exhaust gas strand (5, 6) acts on a predefined inlet area (14, 15) of the inlet face (9) of the catalyst brick (8), characterized in that the inlet areas (14, 15) and / or outlet areas (16, 17) of the catalyst brick ( 8) of different exhaust gas strands (5, 6; 12, 13) are arranged essentially concentrically to each other and that each outlet area (16, 17) is aligned in the flow direction with an inlet area (14, 15) of the corresponding inlet side igen exhaust gas strand (5, 6) is formed.

2. Exhaust system (1) according to claim 1, with two groups (3, 4) of cylinders (2), characterized in that an inlet-side first exhaust sub-strand (5) in the area of entry into the catalyst brick (8) within a preferably by one Inlet cone (6a) formed area of an inlet-side second exhaust branch (6) is guided.

3. Exhaust system (1) according to claim 2, characterized in that the inlet-side first exhaust gas strand (5) is inserted into the inlet cone (6a) of the inlet-side second exhaust gas strand (6) and is welded to it.

4. Exhaust system (1) according to claim 2, characterized in that the inlet cone (6a) is designed as a casting.

5. Exhaust system (1) according to any one of claims 2 to 4, characterized in that the inlet cone (6a) has a preferably conical inner tube (5a) associated with the inlet-side first exhaust gas partial section (5).

6. exhaust system (1) according to claim 5, characterized in that the inlet cone (6a) is integrally formed with the inner tube (5a).

7. exhaust system (1) according to claim 5, characterized in that the inlet cone (6a) is formed in several parts with the inner tube (5a).

8. Exhaust system (1) according to one of claims 1 to 5, with two groups (3, 4) of cylinders (2), the outlet-side exhaust gas strands (12, 13) downstream of the catalyst brick (8) are continued separately, each outlet-side exhaust gas strand (12, 13) directly adjoins an outlet area (16, 17) of the outlet end face (11) of the catalyst brick (8), which is designed to be flush with an inlet area (14, 15) of the corresponding inlet-side exhaust gas strand (5, 6), thereby characterized in that an outlet-side first exhaust gas strand (12) is guided in the region of the outlet from the catalyst brick (8) within a region of an outlet-side second exhaust gas strand (13) preferably formed by an outlet cone (13a).

9. exhaust system (1) according to claim 8, characterized in that the first outlet-side exhaust gas strand (12) is inserted into the outlet cone (13a) of the outlet-side second exhaust gas strand (13) and is welded thereto.

10. Exhaust system (1) according to claim 8, characterized in that the outlet cone (13a) is designed as a casting.

11. Exhaust system (1) according to one of claims 8 to 10, characterized in that the outlet cone (13a) has a, preferably conical, inner tube (12a) associated with the outlet-side first exhaust gas partial section (12).

12. Exhaust system (1) according to one of claims 8 to 11, characterized in that the outlet cone (13a) is formed in one piece with the inner tube (12a).

13. Exhaust system (1) according to one of claims 8 to 11, characterized in that the outlet cone (13a) is formed in several parts with the inner tube (12a).

14. Exhaust system (1) according to one of claims 1 to 13, wherein a predetermined gap (s) is provided between the catalyst brick (8) and the inlet and / or outlet-side first exhaust gas strands (5, 6; 12, 13), characterized in that that a λ probe (20a, 20b) is arranged in the area of the gap (s) such that the exhaust gas flows from all groups (3, 4) of cylinders (2) of this λ probe (20a, 20b) can be monitored.

15. Exhaust system (1) according to claim 14, characterized in that between the inlet-side and / or outlet-side first exhaust system (5, 12) and the catalyst brick (8) in the area of the gap (s) at least one sealing device (21) is arranged.

16. Exhaust system (1) according to claim 15, characterized in that the sealing device (21) has a labyrinth seal (22).

17. Exhaust system (1) according to one of claims 15 and 16, characterized in that the catalyst brick (8) on its inlet and / or outlet end face (9, 11) in the region of the inner tube (5a, 12a) preferably concentrically Has the longitudinal axis (8a) of the catalyst brick (8) extending step (23) or groove (24).

18. Exhaust system (1) according to claim 15 or 16, characterized in that the sealing device (21) has a soft material seal (25).

19. Exhaust system (1) according to claim 18, characterized in that the soft material seal (25) consists of insulating material.

20. Exhaust system (1) according to one of claims 15 to 18, characterized in that the sealing device (21) has at least one material breakthrough for the λ probe (20a, 20b).

21. Exhaust system (1) according to one of claims 1 to 20, characterized in that in the region of the inlet cone (6a) or in the region of the inlet (26a) of the inlet-side first exhaust gas branch (5) into the inlet-side second exhaust gas branch (6) at least one λ probe (20a) is arranged such that the exhaust gas flows from both partial exhaust gas strands (5, 6) can be monitored with this λ probe (20a).

22. Exhaust system (1) according to one of claims 1 to 21, characterized in that in the region of the outlet cone (13) or in the region of the outlet (26b) of the outlet-side first exhaust gas strand (12) from the outlet-side second exhaust gas strand (13) at least a λ probe (20b) is arranged in such a way that the exhaust gas flows from both partial exhaust gas strands (12, 13) can be monitored with this λ probe (20b).

23. Exhaust system (1) according to one of claims 14 or 22, characterized in that the λ probe (20a, 20b) borders on a flow connection (27) between the first and second partial exhaust gas strands (5, 6; 12, 13).

24. Exhaust system (1) according to one of claims 1 to 23, characterized in that the catalyst brick (8) consists of ceramic.

25. Exhaust system (102) for an internal combustion engine with at least one exhaust gas aftertreatment system having at least one first particle filter (105) in the exhaust line (101), wherein at least a second particle filter (106) is arranged downstream of the first particle filter (105) in the exhaust line (101) and wherein at least one first sensor (109, 109 ') is arranged upstream of the first particle filter (105) and at least one second sensor (110) is arranged between the first and second particle filter (105, 106), characterized in that at least a third one is located downstream of the second particle filter Sensor (111) is arranged.

26. Exhaust system (102) in particular according to claim 25, characterized in that at least a first particle filter (105) and at least a second particle filter (106) are arranged in series immediately one behind the other.

27. Exhaust system (102) in particular according to claim 25 or 26, characterized in that the second particle filter (106) is dimensioned smaller than the first particle filter (105).

28. Exhaust system (102) according to one of claims 25 to 27, characterized in that upstream of the first particle filter (105) at least one oxidation catalyst (104) is arranged.

29. Exhaust system (102) in particular according to one of claims 25 to 28, characterized in that at least two components from the group consisting of oxidation catalyst (104), first particle filter (105) and second particle filter (106) are arranged in a common housing (107) ,

30. Exhaust system (102) in particular according to one of claims 25 to 29, characterized in that at least two components from the group consisting of oxidation catalyst (104), first particle filter (105) and second particle filter (106) are arranged in separate housings.

31. Exhaust system (102) in particular according to one of claims 25 to 30, characterized in that the first particle filter (105) in the flow direction (108) from the second particle filter (106) is spaced.

32. Exhaust system (102) in particular according to one of claims 25 to 31, characterized in that at least one particle filter (105, 106) has a particle filter structure with filter channels.

33. Exhaust system (102) in particular according to one of claims 25 to 32, characterized in that at least one particle filter (105, 106) consists of filter substrates, preferably of sintered metal, silicon carbide, cord rivets or similar ceramics. - lb -

34. Exhaust system (102) in particular according to one of claims 28 to 33, characterized in that at least one particle filter (105, 106) has a catalytic coating.

35. Exhaust system (102) according to any one of claims 25 to 34, characterized in that the first, second and / or third sensor (109, 110, 111) are designed as pressure sensors, temperature sensors acoustic and / or photoacoustic sensors.