EP1892397A1 - Internal combustion engine having at least two cylinders and an exhaust gas treatment system - Google Patents

Abstract

The internal-combustion engine has cylinders with a suction line for supplying the cylinders with fresh air and/or fresh mixture, and an exhaust gas discharging system for removal of the exhaust gas from the cylinders. An exhaust gas after treatment system (3) has channel-shaped segments (7a-7d), which are directed in the direction of main flow direction of exhaust gas. The segments are separated from each other in a gas-tight manner. Exhaust supply lines are provided, where each exhaust supply line connects one of the cylinders with one of the channel shaped segment.

Description

The invention relates to an internal combustion engine having at least two cylinders (n ≥ 2), with at least one intake pipe for supplying the n cylinder with fresh air or fresh mixture and a Abgasabführsystem for discharging the exhaust gas from the n cylinders, wherein the Abgasabführsystem an exhaust aftertreatment system for the aftertreatment of the exhaust gas is provided.

In the context of the present invention, the term internal combustion engine includes both diesel engines and gasoline engines.

In the prior art, internal combustion engines are equipped with various exhaust aftertreatment systems to reduce pollutant emissions. Although there is no additional measures during the expansion and expulsion of the cylinder filling at a sufficiently high temperature level and the presence of sufficiently large amounts of oxygen oxidation of the unburned hydrocarbons (HC) and carbon monoxide (CO) instead. However, these reactions come to a halt quickly due to the rapidly decreasing exhaust gas temperature downstream and consequently rapidly decreasing reaction rate. Any lack of oxygen could be compensated by a secondary air injection. However, special reactors and / or filters usually have to be provided in the exhaust system in order to noticeably reduce pollutant emissions under all operating conditions.

Thermal reactors attempt to achieve a substantial post-oxidation of HC and CO in the exhaust system by providing heat insulation and a sufficiently large volume in the exhaust pipe of the exhaust system. The thermal insulation should ensure the highest possible temperature level by minimizing the heat losses, whereas a large exhaust pipe volume ensures a long residence time of the exhaust gases. Both the long residence time and the high temperature level support the desired post-oxidation. A disadvantage is the poor efficiency at substoichiometric Combustion and the high costs. For diesel engines, thermal reactors are not effective because of the generally lower temperature level.

For the above reasons, catalytic reactors are used in the prior art which, using catalytic materials which increase the speed of certain reactions, ensure oxidation of HC and CO even at low temperatures, which is why these catalytic reactors or catalysts are also used as oxidation catalysts can be designated.

In the context of the present invention, all catalysts which serve for the oxidation of HC and CO, regardless of whether they are used in a diesel engine or in a gasoline engine, are to be grouped together under the term "oxidation catalyst", since the mode of operation on which they are based and at least similar to their transferring tasks. The oxidation catalysts also expressly include the three-way catalyst described below.

If, in addition to the oxidation of HC and CO, additional nitrogen oxides are to be reduced in a gasoline engine, this can be achieved by the use of a so-called three-way catalytic converter, which, however, requires a narrow-flow stoichiometric operation (λ≈1) of the gasoline engine. In this case, the nitrogen oxides NO _{x are} reduced by means of the existing unoxidized exhaust gas components, namely the carbon monoxides and the unburned hydrocarbons, wherein at the same time these - serving as a reducing agent - exhaust gas components are oxidized.

As already can be deduced from the above, generally high exhaust gas temperatures are desired or required for an efficient aftertreatment of the exhaust gas by means of oxidation catalyst. Oxidation catalysts require a minimum operating temperature, which may be for example at 150 ° C. This so-called light-off temperature is characterized in that a noticeable increase in the conversion rate with respect to the exhaust components to be oxidized is observed. An oxidation catalyst should reach its light-off temperature as quickly as possible, even within a relatively short period of time, even after a cold start.

In this context, it is therefore fundamentally endeavored to minimize the thermal inertia of the Abgasabführsystems or relevant here portion of Abgasabführsystems, which connects the cylinders with the oxidation catalyst, which can be achieved by reducing the mass and the length of Abgasabführsystems.

Therefore, an oxidation catalyst according to the prior art is arranged as close to the outlet of the internal combustion engine, so that the hot exhaust gases have to travel as short a path to the oxidation catalyst, whereby the exhaust gases are given little time to cool. The close placement or shortened length of the exhaust delivery system also results in a lower mass of the exhaust delivery system. Both ensure that the oxidation catalyst reaches the required operating temperature or light-off temperature as quickly as possible.

In order to support the effect described or not to weaken adversely, preferably no further exhaust aftertreatment system, but also no other component - for example, the turbine of an exhaust gas turbocharger - between internal combustion engine and oxidation catalyst d. H. provided upstream of the oxidation catalyst, since this would increase the mass and thus the thermal inertia of the Abgasabführsystems.

Further optionally provided in Abgasabführsystem exhaust aftertreatment systems, such as a storage catalyst, an SCR catalyst, a particulate filter or the like, are preferably to be arranged downstream of the oxidation catalyst. The oxidation processes taking place in the oxidation catalytic converter, especially in the case of substoichiometric operation (λ <1) of the internal combustion engine due to the high concentration of unburned hydrocarbons in the exhaust gas, ensure a noticeable increase in the exhaust gas temperature and thus not only for heating of the oxidation catalytic converter, but also for a catalytic converter Heating the downstream provided exhaust aftertreatment systems, which are flowed through by the hot exhaust gas.

Figures 1a and 1b show a first embodiment of the prior art using the example of a four-cylinder internal combustion engine in which an oxidation catalyst 104a as close to the cylinders 101a, 101b, 101c, 101d that is arranged at the outlet of the internal combustion engine.

This is a so-called 4-in-1 system, in which the exhaust gases of the four cylinders 101a, 101b, 101c, 101d with four short exhaust pipes 102a, 102b, 102c, 102d are fed to a single catalyst 104a. Starting from this catalytic converter 104a, the exhaust gases are then continued in a common overall exhaust gas line 106.

A disadvantage of this structural design of the Abgasabführsystems is that the dynamic wave processes in Abgasabführsystem can affect the charge cycle unfavorable. Among other things, it has to be taken into account that pressure fluctuations in gaseous media propagate as waves which can pass through the exhaust gas lines 102a, 102b, 102c, 102d and can be reflected.

In the so-called preload discharge, which occurs upon opening of an exhaust valve of a cylinder 101a, 101b, 101c, 101d, the combustion gases flow due to the high pressure level prevailing toward the end of the combustion in the cylinder 101a, 101b, 101c, 101d and the high pressure difference associated therewith Combustor and Abgasabführsystem at high speed through the outlet opening in the exhaust pipes 102a, 102b, 102c, 102d. This pressure-driven flow process is accompanied by a high pressure peak, which is also referred to as Vorlastausstoß and propagates along the exhaust pipes 102a, 102b, 102c, 102d with speed of sound.

The pressure spike of the preload exhaust may be reflected in the exhaust evacuation system at an open end as a negative pressure wave and at a closed end as an overpressure wave. The flow in the tube then results from the superposition of the leading and reflected wave.

To optimize the charge exchange, it would be advantageous to design the exhaust system in such a way that towards the end of the evacuation of the exhaust gases from a cylinder 101a, 101b, 101c, 101d a vacuum wave arrives at the outlet, which lead to a certain suction of the exhaust gases and thus would support the evacuation of the exhaust gases. On the other hand, it would be disadvantageous if, at the end of the charge cycle, an overpressure shaft reaches the outlet opening, which not only prevents further exhausting of exhaust gas from the cylinder 101a, 101b, 101c, 101d, but already exhausted exhaust gas again into the cylinder 101a, 101b, 101c , 101d pushes back. Depending on the version of the Oxidation catalyst 104a and the volume of the catalyst 104a, the provided in the exhaust system oxidation catalyst 104a must be regarded as a closed pipe end, which has the described disadvantageous effect. FIG. 1b shows the oxidation catalytic converter 104a serving as the exhaust gas aftertreatment system 103a in cross section along the line A - A, wherein the monolith serving as a carrier substrate can be recognized.

In particular, when a particulate filter serving as an exhaust aftertreatment system is the subject of consideration, the exhaust aftertreatment system must probably be considered a closed pipe end, because honeycomb filters are generally used which comprise a multiplicity of ducts which alternately d. H. are closed in the checkerboard pattern, so that the exhaust gas flows into the channels open at the inlet of the honeycomb filter and on the way to the outlet, the channel walls of these channels closed to exit must flow to get into a channel which is open to the outlet of the honeycomb filter , In the case of surface filters, the pore diameters of the carrier substrate are so small that the soot particles do not penetrate into the filter material, but deposit themselves as filter cakes on the surface of the filter.

In connection with the catalyst arrangement shown in FIGS. 1a and 1b, in addition to any reflection to be considered, the simple unimpeded propagation of the individual exhaust gas flows or of the overpressure waves in the exhaust gas lines 102a, 102b, 102c, 102d is of greater relevance; not least, because unfavorable reflections can be prevented by an appropriate tuning of the tube lengths of the exhaust pipes 102a, 102b, 102c, 102d or only play a role at a certain speed.

Thus, the preload output that propagates along the first exhaust passage 102a upon opening of the first cylinder 101a can freely propagate into the remaining three exhaust passages 102b, 102c, 102d, to the exhaust ports of the respective cylinders 101b, 101c, 101d, and the discharge of the Exhaust gases from these cylinders 101b, 101c, 101d adversely affect or hinder.

For these reasons, a modified catalyst arrangement has been developed according to the prior art, which - again using the example of a four-cylinder internal combustion engine - is shown in Figures 2a and 2b.

In each case, two exhaust pipes 102a, 102b, 102c, 102d are combined in pairs and fed to two pre-catalysts 104b, 104c or Interimskatalysatoren. The two exhaust pipes 105a, 105b, with which the exhaust gases are discharged from the two pre-catalysts 104b, 104c, open into a common, downstream arranged third catalyst 104a, which is necessary because the two pre-catalysts 104b, 104c usually not a sufficiently large catalyst volume have to ensure a satisfactory exhaust aftertreatment even with large amounts of exhaust gas.

FIG. 2b shows the exhaust aftertreatment systems 103b, 103c serving as pre-catalysts 104b, 104c in cross section along the line B-B, wherein the monoliths serving as carrier substrates can be seen. The exhaust gases are forwarded from the third catalytic converter 104a in a common exhaust gas line 106.

The embodiment illustrated in FIGS. 2a and 2b is referred to as a 4-in-2-in-1 system in which the four short exhaust pipes 102a, 102b, 102c, 102d of the four cylinders 101a, 101b, 101c, 101d-in stages- are first merged into two exhaust pipes 105a, 105b and finally to an overall exhaust line 106.

The exhaust pipes 102a, 102b, 102c, 102d of the individual cylinders 101a, 101b, 101c, 101d are not randomly but in a targeted manner paired so that two cylinders 101a, 101b, 101c, 101d are merged, their control times 360 ° KW are offset from each other, so that the Vorlastausstoß or the exhaust gas flow of the one cylinder 101a, 101b, 101c, 101d can not affect the charge exchange of the other involved cylinder 101a, 101b, 101c, 101d. Specifically, the exhaust pipes 102a, 102d of the first and fourth cylinders 101a, 101d and the exhaust pipes 102b, 102c of the second and third cylinders 101b, 101c are merged. Thus, with this arrangement of the exhaust pipes 102a, 102b, 102c, 102d, it is not harmful that the preload output of the first cylinder 101a propagates into the exhaust pipe 102d of the fourth cylinder 101d because the exhaust ports of the fourth cylinder 101d during the exhaust stroke of the first cylinder 101a are closed.

The preload output or the exhaust gas flow of the first cylinder 101a may indeed be after the merging of the two exhaust pipes 105a, 105b on the third catalyst 104a in the direction of the second and third cylinders 101b, 101c propagate. The distance that the exhaust gas or the Vorlastausstoß has to cover starting from the first cylinder 101a to propagate until the outlet of the second and / or third cylinder 101b, 101c, there to possibly affect the charge exchange, is so far increased that when the Vorlastausstoßes the outlet openings of these two cylinders 101b, 101c are already closed.

Compared with the embodiment shown in FIGS. 1a and 1b, the problems with regard to the charge exchange or the preload emission can thus be eliminated.

However, in order to continue to realize a close arrangement of the exhaust aftertreatment on the internal combustion engine, additional catalysts 104b, 104c must be provided, so that the number of catalysts 104a, 104b, 104c increases. Instead of a catalyst 104a now a total of three catalysts 104a, 104b, 104c are required.

This has disadvantages not only from a cost point of view. Rather, a dense packaging of the exhaust system is made difficult, but this is desirable due to the very limited space in principle in the design of the exhaust system.

Against this background, it is the object of the present invention to provide an internal combustion engine according to the preamble of claim 1, with which the known from the prior art disadvantages are eliminated and in particular a close-coupled arrangement of the exhaust aftertreatment system is realized, which is both inexpensive, as well as the exhaust flows of the cylinder separates in the required manner to avoid adverse effects on the charge cycle of the individual cylinders.

• ■ das vom Abgas durchströmte Abgasnachbehandlungssystem n kanalförmige Segmente aufweist, die in Richtung der Hauptströmungsrichtung des Abgases ausgerichtet sind und jeweils von einem gehäuseähnlichen Mantel umgeben sind, wodurch die kanalförmigen Segmente gasdicht voneinander getrennt sind, und
• ■ n Abgaszuführleitungen vorgesehen sind, wobei jede Abgaszuführleitung einen Zylinder mit einem kanalförmigen Segment verbindet.

This object is achieved by an internal combustion engine with at least two cylinders (n ≥ 2), with at least one intake to supply the n cylinder with fresh air or fresh mixture and a Abgasabführsystem for discharging the exhaust gas from the n cylinders, wherein the Abgasabführsystem an exhaust aftertreatment system for aftertreatment the exhaust gas is provided, and which is characterized in that

• The exhaust aftertreatment system through which the exhaust gas flows has channel-shaped segments which extend in the direction of the main flow direction of the exhaust gas are aligned and are each surrounded by a housing-like jacket, whereby the channel-shaped segments are separated from each other gas-tight, and
• ■ n Abgaszuführleitungen are provided, each Abgaszuführleitung connects a cylinder with a channel-shaped segment.

The gas-tight separated channel-shaped segments of the exhaust aftertreatment system of the internal combustion engine according to the invention ensure that the exhaust gas flows of the individual cylinders of the internal combustion engine are isolated from each other during exhaust aftertreatment.

The evacuated from the individual cylinders d. H. exhaust gases discharged during the exhaust stroke are supplied to the individual channel-shaped segments by means of separate exhaust gas supply lines, so that the exhaust gas flows of the individual cylinders are separated from each other upstream of the after-treatment. In each case an exhaust gas supply line connects a cylinder with a channel-shaped segment.

The exhaust flow or the preload output of a cylinder can therefore not propagate from the exhaust aftertreatment system in the direction of another cylinder and adversely affect the charge cycle of this cylinder.

The effect known from the state of the art that the cylinders of the internal combustion engine interfere with one another when pushing out their exhaust gases-as is observed, for example, in the embodiment shown in FIGS. 1a and 1b-is therefore not to be feared.

The internal combustion engine according to the invention or the structural design of the exhaust aftertreatment system thus allows the advantageous close-coupled arrangement of the exhaust gas treatment system.

In this respect, the inventive design of the exhaust aftertreatment system also offers advantages in terms of cost. In addition, a dense packaging of the exhaust system can be realized.

Thereby, the object underlying the invention is achieved, namely to provide an internal combustion engine with which the known from the prior art disadvantages are eliminated and in particular a close-coupled arrangement of the exhaust aftertreatment system is realized, which is both cost, as well as the exhaust gas flows of the cylinder in the required manner to avoid adverse effects on the charge cycle of the individual cylinders.

The channel-shaped segments are surrounded by a housing-like jacket. This jacket can be integrally formed or modularly constructed of several part walls. With regard to the last-mentioned variant, embodiments are advantageous in which a common housing is provided, which encloses and bundles the channel-shaped segments, wherein the individual segments are separated from one another by partition walls or insulated from one another. The boundary walls forming the jacket are then preferably connected to one another.

If the exhaust aftertreatment system comprises a carrier substrate or a honeycomb body or monoliths, then the walls forming the carrier substrate or the monoliths are not partitions or jacket sections within the meaning of the present application.

Rather, embodiments are advantageous in which each segment has an independent carrier substrate.

Further advantageous embodiments of the internal combustion engine are discussed in connection with the subclaims.

Embodiments of the internal combustion engine in which n exhaust-gas discharge lines are provided are advantageous, wherein each exhaust-gas discharge line connects a channel-shaped segment to a total exhaust gas line arranged downstream.

In this embodiment, the exhaust gas flows of the individual cylinders are also performed after the exhaust aftertreatment, ie downstream of the exhaust aftertreatment system, first in separate Abgasabführleitungen.

The distance that the exhaust or the Vorlastausstoß must proceed from one cylinder to the outlet of another cylinder, is thereby increased again. The length of the Abgaszuführleitungen and Abgasabführleitungen is dimensioned or chosen in such a way that when the Vorlastausstoßes a cylinder of the outlet of the vulnerable cylinder is closed upon arrival.

As a result, it can be prevented that the cylinders mutually adversely affect each other when expelling the exhaust gases when the exhaust flow or the Vorlastausstoß a cylinder propagates in the exhaust pipe of another cylinder in the direction of the internal combustion engine.

Advantageous embodiments of the internal combustion engine, in which the channel-shaped segments are arranged in the manner adjacent to each other, that the housing-like shells of the segments touch at least partially.

This creates a heat coupling between the individual channel-shaped segments. The channel-shaped segments support each other or mutually in their heating process, which offers advantages especially during the warm-up phase after a cold start.

If the considered exhaust gas aftertreatment system is an oxidation catalytic converter, the oxidation processes taking place in one segment contribute to the heating of the adjacent segments, so that the oxidation catalytic converter or the individual segments reach their light-off temperature much faster, which has an advantageous effect on the pollutant emissions - in particular on the emissions of unburned hydrocarbons.

Advantageous embodiments of the internal combustion engine, in which the exhaust aftertreatment system is an oxidation catalyst.

As explained in detail in the introduction, a close-coupled arrangement is desired or desired, in particular in oxidation catalysts, since the - during the warm-up phase - due to the not yet working at operating temperature engine - increased concentrations of unburned hydrocarbons in the Exhaust gas, which is characteristic for a cold start, should be reduced as quickly as possible by means of an exhaust aftertreatment.

As a result of the arrangement of the oxidation catalytic converter close to the engine, an improved emission behavior of the internal combustion engine is ensured in the warm-up phase or after a cold start.

Embodiments of the internal combustion engine in which the exhaust aftertreatment system is a storage catalytic converter or an SCR catalytic converter are advantageous.

In internal combustion engines, which are operated with an excess of air, the nitrogen oxides NO _{x present} in the exhaust gas can in principle - ie due to the lack of reducing agents - not be reduced without additional measures.

To reduce the nitrogen oxides, for example, selective catalysts - so-called SCR catalysts - are used, in which targeted reducing agent is introduced into the exhaust gas to selectively reduce the nitrogen oxides. As a reducing agent, not only ammonia and urea but also unburned hydrocarbons are used. The latter is also referred to as HC enrichment, wherein the unburned hydrocarbons are introduced directly into the exhaust tract or else by internal engine measures, for example by a post-injection of additional fuel into the combustion chamber after the actual combustion supplied.

Basically, the nitrogen oxide emissions can also use a so-called nitrogen oxide storage catalytic converter (LNT - L ean N O _x T rap) can be reduced. The nitrogen oxides are first - during a lean operation of the internal combustion engine - absorbed in the catalyst, ie collected and stored, and then during a regeneration phase, for example by means of a substoichiometric operation (for example, λ <0.95) of the engine to be reduced in oxygen deficiency, then under The more commonly used in the exhaust unburned hydrocarbons can serve as a reducing agent.

The temperature of the storage catalyst (LNT) should preferably be in a temperature window between 200 ° C and 450 ° C, wherein the contained in the exhaust gas Sulfur, which is also absorbed in the LNT, must be removed on a regular basis. For this purpose, the LNT must be heated to high temperatures, usually between 600 ° C and 700 ° C, and supplied with a reducing agent.

Like the oxidation catalyst already described above, the storage catalytic converter thus also requires a certain operating temperature in order to satisfactorily convert the nitrogen oxides present in the exhaust gas. Particularly high temperatures require regularly performed desulfurization.

For this reason, it may be useful to arrange a LNT close to the engine. Thus, from the prior art exhaust aftertreatment systems are known in which a plurality of storage catalytic converters are provided in the exhaust system.

In this case, a first LNT, which has a comparatively small volume and with which the nitrogen oxides are to be satisfactorily converted during the warm-up phase and low exhaust gas mass flows, arranged close to the engine, whereas with larger exhaust masses, the nitrogen oxides by means of a second LNT, which is arranged downstream of the first LNT and a larger volume, to be post-treated. The small volume of the first LNT and the close-coupled arrangement of this LNT ensure sufficient conversion of the nitrogen oxides after a cold start.

Embodiments of the internal combustion engine in which the exhaust aftertreatment system is a particle filter are advantageous.

To minimize the emission of soot particles so-called regenerative particulate filters are used in the prior art, which filter out and store the soot particles from the exhaust gas, these soot particles are intermittently burned in the regeneration of the filter. For this purpose, oxygen or an excess of air in the exhaust gas is required to oxidize the soot in the filter, which can be achieved for example by a superstoichiometric operation (λ> 1) of the internal combustion engine.

The high temperatures for the regeneration of the particulate filter - about 550 ° C in the absence of catalytic support - are achieved in operation only at high loads and high speeds. Therefore, additional measures must be used to: to ensure a regeneration of the filter under all operating conditions. A close-coupled arrangement may aid in efforts to bring the particulate filter up to the high temperatures required for regeneration.

The exhaust aftertreatment systems described above - particulate filter, storage catalytic converter and SCR catalytic converter - show that the problem described using the example of the oxidation catalytic converter is similar in the case of other exhaust aftertreatment systems. Accordingly, the same measures to solve the problems are effective. The internal combustion engine according to the invention combines the design features or solution features in this regard.

Of course, further exhaust treatment systems such. As particle filter, storage catalyst and SCR catalysts can be arranged to meet the respective requirements of the emission control.

Fig. 1a

schematisch eine erste Katalysatoranordnung nach dem Stand der Technik,

Fig. 1b

schematisch den Katalysator der in Figur 1a dargestellten Katalysatoranordnung im Querschnitt entlang der Linie A - A,

Fig. 2a

schematisch eine zweite Katalysatoranordnung nach dem Stand der Technik,

Fig. 2b

schematisch die beiden Vorkatalysatoren der in Figur 2a dargestellten Katalysatoranordnung im Querschnitt entlang der Linie B - B,

Fig.3a

schematisch eine erste Ausführungsform einer Katalysatoranordnung der Brennkraftmaschine, und

Fig. 3b

schematisch den Katalysator der in Figur 3a dargestellten Katalysatoranordnung im Querschnitt entlang der Linie C - C.

In the following the invention with reference to an embodiment according to the figures 1a to 3b will be described in more detail. Hereby shows:

Fig. 1a

schematically a first catalyst arrangement according to the prior art,

Fig. 1b

1 schematically shows the catalyst of the catalyst arrangement shown in FIG. 1 a in a cross section along the line A - A,

Fig. 2a

schematically a second catalyst arrangement according to the prior art,

Fig. 2b

2 schematically shows the two precatalysts of the catalyst arrangement shown in FIG. 2 a in cross section along the line B-B,

3a

schematically a first embodiment of a catalyst arrangement of the internal combustion engine, and

Fig. 3b

schematically the catalyst of the catalyst arrangement shown in Figure 3a in cross section along the line C - C.

Figures 1a, 1b, 2a and 2b have already been discussed in detail in the description of the prior art, which is why at this point no further comments are to be made and reference is made to the introduction to the description.

FIG. 3a schematically shows a first embodiment of a catalytic converter arrangement of the internal combustion engine according to the invention. FIG. 3b shows the used catalyst 4 of the catalyst arrangement shown in FIG. 3a in cross section along the line C-C.

The internal combustion engine has four cylinders 1a, 1b, 1c, 1d and an exhaust gas discharge system for exhausting the exhaust gases from the four cylinders 1a, 1b, 1c, 1d. In the exhaust gas removal system serving as exhaust aftertreatment system 3 oxidation catalyst 4 is arranged, with which the exhaust gases are post-treated, in particular carbon monoxide and unburned hydrocarbons are oxidized.

The exhaust gas flow through the oxidation catalyst 4 has - as shown in Figure 3b - four channel-shaped segments 7a, 7b, 7c, 7d, which are aligned in the direction of the main flow direction of the exhaust gases, wherein each one Abgaszuführleitung 2a, 2b, 2c, 2d a cylinder 1a , 1b, 1c, 1d with a channel-shaped segment 7a, 7b, 7c, 7d connects. The channel-shaped segments 7a, 7b, 7c, 7d are each surrounded by a housing-like jacket and thereby separated from each other gas-tight.

The gas-tight separated channel-shaped segments 7a, 7b, 7c, 7d of the oxidation catalyst 4 ensure together with the four Abgaszuführleitungen 2a, 2b, 2c, d, that the exhaust gas flows of the individual cylinders 1a, 1b, 1c, 1d of the internal combustion engine during the exhaust aftertreatment and isolated from each other upstream of the post-treatment d. H. are separated.

In the embodiment illustrated in FIGS. 3a and 3b, the housing-like jacket of the channel-shaped segments 7a, 7b, 7c, 7d is not made in one piece, but has a modular construction. In this case, a common housing 8 is provided which encloses and bundles the four channel-shaped segments 7a, 7b, 7c, 7d, the individual segments 7a, 7b, 7c, 7d being separated from one another by partitions 9a, 9b. The partitions 9a, 9b serve simultaneously as multiple boundary walls, whereby a heat coupling between the Segments 7a, 7b, 7c, 7d is realized, which is why the segments 7a, 7b, 7c, 7d support each other in their heating process. Each segment 7a, 7b, 7c, d has an independent carrier substrate.

There are four Abgasabführleitungen 5a, 5b, 5c, 5d provided, each Abgasabführleitung 5a, 5b, 5c, 5d connects a channel-shaped segment 7a, 7b, 7c, 7d with a downstream total exhaust gas line 6. As a result, the exhaust gas flows of the individual cylinders 1a, 1b, 1c, 1d also after the exhaust aftertreatment d. H. downstream of the oxidation catalyst 4 initially in separate Abgasabführleitungen 5a, 5b, 5c, 5d performed.

The distance which the exhaust gas or the Vorlastausstoß starting from a cylinder 1 a, 1 b, 1 c, 1 d must travel to the outlet of another cylinder 1 a, 1 b, 1 c, 1 d, is thereby increased.

reference numeral

1a

first cylinder

1b

second cylinder

1c

third cylinder

1d

fourth cylinder

2a

first exhaust gas supply line

2 B

second exhaust gas supply line

2c

third exhaust gas supply line

2d

fourth exhaust gas supply line

3

aftertreatment system

4

oxidation catalyst

5a

first exhaust gas discharge line

5b

second exhaust gas discharge line

5c

third exhaust gas discharge line

5d

fourth exhaust gas discharge line

6

Total exhaust pipe

7a

first channel-shaped segment

7b

second channel-shaped segment

7c

third channel-shaped segment

7d

fourth channel-shaped segment

8th

common housing

9a

first partition

9b

second partition

101

first cylinder

101b

second cylinder

101c

third cylinder

101d

fourth cylinder

102

first exhaust pipe

102b

second exhaust pipe

102c

third exhaust pipe

102d

fourth exhaust pipe

103a

aftertreatment system

103b

aftertreatment system

103c

aftertreatment system

104a

oxidation catalyst

104b

precatalyzer

104c

precatalyzer

105a

exhaust pipe

105d

exhaust pipe

106

Total exhaust pipe

° CA

Degree crank angle

n

Number of cylinders

λ

air ratio

Claims (10)

Internal combustion engine with at least two cylinders (n ≥2) (1a, 1b, 1c, 1d), with at least one suction line for supplying the n cylinders (1a, 1b, 1c, 1d) with fresh air or fresh mixture and an exhaust gas removal system for discharging the exhaust gas from the n cylinders (1a, 1b, 1c, 1d), wherein an exhaust aftertreatment system (3) is provided in the exhaust gas removal system for the aftertreatment of the exhaust gas,
characterized in that The exhaust aftertreatment system (3) through which the exhaust gas flows has n channel-shaped segments (7a, 7b, 7c, 7d) which are aligned in the direction of the main flow direction of the exhaust gas and are each surrounded by a housing-like jacket, whereby the channel-shaped segments (7a, 7b, 7c, 7d) are separated from each other gas-tight, and N exhaust gas supply lines (2a, 2b, 2c, 2d) are provided, each Abgaszuführleitung (2a, 2b, 2c, 2d) a cylinder (1a, 1b, 1c, 1d) with a channel-shaped segment (7a, 7b, 7c, 7d ) connects. Internal combustion engine according to claim 1, characterized in that the housing-like jacket is of modular construction, wherein a common housing (8) is provided, which encloses the n channel-shaped segments (1a, 1b, 1, c, 1d), and the individual segments (7a , 7b, 7c, 7d) are separated from one another by partition walls (9a, 9b). Internal combustion engine according to claim 1 or 2, characterized in that each segment (7a, 7b, 7c, 7d) has an independent carrier substrate. Internal combustion engine according to one of the preceding claims, characterized in that n Abgasabführleitungen (5a, 5b, 5c, 5d) are provided, wherein each exhaust gas discharge line (5a, 5b, 5c, 5d) connects a channel-shaped segment (7a, 7b, 7c, 7d) to a downstream total exhaust gas line (6). Internal combustion engine according to one of the preceding claims, characterized in that the channel-shaped segments (7a, 7b, 7c, 7d) are arranged adjacent to each other in such a way that the housing-like shells of the segments (7a, 7b, 7c, 7d) touch each other at least partially , Internal combustion engine according to one of the preceding claims, characterized in that the exhaust aftertreatment system (3) is an oxidation catalyst (4) or contains an oxidation catalyst (4). Internal combustion engine according to one of claims 1 to 5, characterized in that the exhaust aftertreatment system (3) is a storage catalyst or contains a storage catalyst. Internal combustion engine according to one of claims 1 to 5, characterized in that the exhaust aftertreatment system (3) is an SCR catalyst or contains an SCR catalyst. Internal combustion engine according to one of claims 1 to 5, characterized in that the exhaust aftertreatment system (3) is a particle filter or contains a particle filter. Internal combustion engine according to one of the preceding claims, characterized in that further exhaust gas treatment systems are arranged in the further course of the exhaust gas line (6).

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