DE102018120173A1 - Exhaust tract for an internal combustion engine and internal combustion engine - Google Patents

Abstract

The invention relates to an exhaust tract for an internal combustion engine, comprising at least one exhaust manifold (5; 6), the exhaust manifold (5; 6) being designed so that cylinders (3) of the internal combustion engine (1) can flow through it, and having an exhaust line (9; 10) through which the exhaust gas can flow ), a turbine (11; 13) of an exhaust gas turbocharger (12; 14) being received so that it can flow through, and wherein an exhaust gas cleaning unit (19) can be flowed through downstream of the exhaust gas turbocharger (12; 14) in the exhaust tract (7) is received, and wherein the exhaust tract (7) for exhaust gas guidance of the exhaust gas of the internal combustion engine (1) is designed to flow from the exhaust manifolds (5, 6) into the exhaust gas purification unit (19). According to the invention, a heating stage (20) is provided for the application of the exhaust gas cleaning unit (19) in accordance with requirements.

Description

The invention relates to an exhaust tract for an internal combustion engine according to the preamble of claim 1. Furthermore, the invention relates to an internal combustion engine according to claim 7.

It is known to provide an exhaust gas purification unit in an exhaust tract of an internal combustion engine, which is used to reduce pollutant emissions. This exhaust gas purification unit can be designed as a function of the internal combustion engine, which can be designed as a gasoline engine or as a diesel engine. For example, it can have a catalyst and / or a particle filter. Regardless of the specific structure of the exhaust gas cleaning unit, a temperature of an exhaust gas of the internal combustion engine flowing through the exhaust tract is relevant for the efficient operation of the exhaust gas cleaning unit. This means that the exhaust gas, but primarily the exhaust gas aftertreatment, must have a certain temperature when it flows into the exhaust gas cleaning unit so that it can effectively and efficiently reduce the pollutant content of the exhaust gas flowing through it.

The heat loss sources present in the exhaust tract, such as, in particular, pipes of the exhaust tract and also turbines of exhaust gas turbochargers, which lead to a reduction in the heat inherent in the exhaust gas, are problematic. In the pipelines, heat is lost in particular via wall heat losses, in the turbines in particular by reducing the enthalpy, as a result of expansion of the exhaust gas in the turbine, and in wall heat losses.

The disclosure DE 100 15 291 A1 discloses an internal combustion engine with an exhaust tract, a first exhaust gas turbocharger and a second exhaust gas turbocharger being accommodated in the exhaust tract. A flow and flow around the exhaust gas turbocharger is controlled with the aid of control elements, the control elements being controlled as a function of an output to be provided by the internal combustion engine.

The published documents also disclose DE 10 2007 037 087 A1 and DE 10 2009 006 359 A1 and the patent specification EP 2 402 576 B1 an internal combustion engine with two exhaust gas turbochargers, the turbines are accommodated in the exhaust tract of the internal combustion engine. Here, too, the regulation of the exhaust gas flowing through the exhaust tract serves to optimize the performance of the internal combustion engine, in particular in the case of DE 10 2009 006 359 A1 exhaust gas recirculation is taken into account.

The published documents US 2010/0071365 A1 and EP 1 640 598 A1 one internal combustion engine can be removed in each case, which likewise has two exhaust gas turbochargers, a first particle filter and a second particle filter arranged in the exhaust gas tract between the two turbines of the exhaust gas turbocharger being provided in an exhaust gas tract of the internal combustion engine.

It is therefore the object of the present invention to provide an exhaust gas tract for an internal combustion engine which is distinguished by an increase in the reduction in exhaust gas emissions. Another object of the present invention is to provide an internal combustion engine with reduced pollutant emissions.

The object is achieved by an exhaust tract for an internal combustion engine with the features of claim 1. The further object is achieved by an internal combustion engine with the features of patent claim 7. Advantageous refinements with expedient and non-trivial developments of the invention are specified in the respective subclaims.

An exhaust tract according to the invention for an internal combustion engine, comprising at least one exhaust manifold, the exhaust manifold being designed so that cylinders of the internal combustion engine can flow through it, and having an exhaust gas line through which a turbine of an exhaust gas turbocharger can be flowed through. Downstream of the exhaust-gas turbocharger, an exhaust-gas cleaning unit is received in the exhaust tract so that it can flow through. The exhaust tract is designed so that the exhaust gas of the internal combustion engine can flow from the exhaust manifolds into the exhaust gas purification unit. According to the invention, a heating stage is provided in order to act upon the exhaust gas cleaning unit as required.

In other words, in addition to the heating power provided by the heat of the exhaust gas, or in other words, the exhaust gas tract is additionally supplied with heating power, which leads to an increase in an overall temperature of the exhaust tract, in particular the exhaust gas cleaning unit. The advantage can be seen in an increase in the reduction in pollutant emissions, since the emission reduction can be carried out efficiently and effectively if the required temperature of the exhaust gas tract, in particular the exhaust gas cleaning unit, is sufficiently high.

In particular in a so-called cold start operation and / or at particularly low load and / or speed points of the The internal combustion engine is low due to the low exhaust gas temperature and / or low exhaust gas enthalpy, the temperature of the exhaust tract and in particular the exhaust gas cleaning unit, so that the emission reduction can only be incomplete or very reduced. With the help of the heating stage, heat can be supplied to the exhaust tract regardless of the operating point of the internal combustion engine, so that the exhaust gas cleaning unit can be operated effectively and efficiently. In other words, this means that the heating level inherent in the exhaust gas flowing through the exhaust tract can be increased with the aid of the heating stage.

The advantage of a controllable heating level can be seen in the fact that, depending on the temperature of the exhaust tract and / or the exhaust gas temperature, the additional heating output can be adjusted quantitatively in such a way that the exhaust gas cleaning unit can be acted upon in a cost-effective and yet needs-based manner.

The exhaust gas temperature required for effective and efficient pollutant reduction in the exhaust gas cleaning unit before entering the exhaust gas cleaning unit and / or an integral value of the heating output in front of the exhaust gas cleaning unit, which depends, for example, on the heating output of the exhaust gas, heat losses in the exhaust gas tract, is used to define a so-called performance point used, which is individual for each form of the exhaust tract according to the invention, since it depends on its components. Depending on this credit point, the heating level is used and regulated. In this context, the term demand-based loading can also be explained, since the demand-based loading takes place depending on a loss of heat of the components through which flow, such as, for example, exhaust pipes, turbines.

With conventional drive concepts, which usually have exhaust gas turbochargers, whereby the exhaust gas turbochargers can bring not only the advantage of an increase in performance of the internal combustion engine, but also a reduction in the displacement of the internal combustion engine, it is necessary to bring the exhaust gas cleaning unit quickly to the necessary operating temperature, which reduces the pollutant emissions the emission control unit is necessary.

The faster the corresponding temperature is reached, the earlier it is time to reduce pollutant emissions such as hydrocarbons (H _x C _y ), nitrogen oxides (N0 _x ) and carbon monoxides (CO) in a catalytic converter of the exhaust gas cleaning unit.

A loss of heating power in the exhaust system can be compensated for by the heating level.

The advantage of the exhaust tract according to the invention can be seen in particular in that the exhaust tract is optimally flowed through by operating the heating stage in order to achieve the lowest emissions with high specific power of the internal combustion engine.

With the help of the operation of the heating stage, a so-called lightoff of the exhaust gas cleaning unit, in particular starting from a cold start operation of the internal combustion engine, can be achieved earlier than with a conventional exhaust tract according to the prior art. In other words, the exhaust gas temperature upstream of the exhaust gas cleaning unit, in particular at the inlet of the exhaust gas cleaning unit, has the minimum temperature required for the effective and efficient operation of the exhaust gas cleaning unit more quickly.

In addition, the regeneration temperature of the particle filter is reached earlier and more frequently.

A second aspect of the invention relates to an internal combustion engine with an exhaust tract according to one of claims 1 to 6. The advantage of the internal combustion engine with the exhaust tract according to one of claims 1 to 6 can be seen in a significant reduction in pollutant emissions compared to the prior art. Another advantage is the possibility of achieving an improved starting performance of a motor vehicle having the internal combustion engine according to the invention. This means, in particular, the significant reduction of a so-called turbo lag due to the achievable higher torque in the lower load and in particular speed range of the internal combustion engine. In other words, that in particular when switching from serial exhaust gas turbocharger operation to parallel exhaust gas turbocharger operation, or from switching on a further exhaust gas turbocharger with and after reaching the power point, an early, i.e. high torque of the internal combustion engine is available even at low engine speeds.

In one embodiment of the internal combustion engine according to the invention, it has at least two independently configured exhaust manifolds. If the exhaust tract has more than one exhaust gas turbocharger, each exhaust gas turbocharger can thus be assigned an exhaust manifold through which exhaust gas flows through the cylinders assigned to it. The size of the exhaust gas turbocharger can be adjusted accordingly and possibly reduced. In other words, this means that the turbine is supplied with a maximum exhaust gas mass flow from only part of the internal combustion engine. to In order to achieve a preferably high efficiency of the exhaust gas turbocharger, the turbine can thus be designed to be smaller than it would have to be when an exhaust gas is applied from all exhaust manifolds of the internal combustion engine. Also, in particular in the case of a smaller exhaust gas turbocharger in the lower load and / or speed range of the internal combustion engine, an improved response behavior of the exhaust gas turbocharger can be achieved on account of a smaller moment of inertia of its running gear.

• 1 in einer schematischen Darstellung eine erfindungsgemäße Verbrennungskraftmaschine mit einem erfindungsgemäßen Abgastrakt in einem ersten Ausführungsbeispiel.

Further advantages, features and details of the invention result from the following description of preferred exemplary embodiments and from the drawing. The features and combinations of features mentioned above in the description and the features and combinations of features mentioned below in the description of the figures and / or shown alone in the figures can be used not only in the combination indicated in each case, but also in other combinations or on their own, without the scope of Leaving invention. Identical reference symbols are assigned to identical or functionally identical elements. It shows:

• 1 a schematic representation of an internal combustion engine according to the invention with an exhaust tract according to the invention in a first embodiment.

An internal combustion engine according to the invention 1 is according to a first embodiment 1 educated. The internal combustion engine 1 has a first cylinder bank 2 comprising at least two cylinders 3 , as well as a second cylinder bank 4 which also have three cylinders 3 includes, on. Every cylinder bank 2 . 4 has an exhaust manifold, the first cylinder bank 2 a first exhaust manifold 5 and the second cylinder bank 4 a second exhaust manifold 6 having.

Each of the two exhaust manifolds 5 . 6 , the exhaust system according to the invention 7 the internal combustion engine 1 is assigned, can be flowed through with outlet channels 8th the cylinder 3 connected, so that from the cylinder 3 exhaust gas from the internal combustion engine during its exhaust stroke 1 via the outlet channels 8th in the exhaust system 7 can flow.

The exhaust tract 7 has a first exhaust pipe 9 on. In the first exhaust pipe 9 is a first turbine 11 of a first exhaust gas turbocharger 12 arranged to flow through. The first turbine 11 corresponding first compressor 15 of the first exhaust gas turbocharger 12 is in an intake line of the internal combustion engine, not shown 1 flowable and upstream of the internal combustion engine 1 recorded and serves to compress extracted combustion air from the internal combustion engine 1 ,

The exhaust manifold 5 . 6 open upstream of the first turbine 11 in the first exhaust pipe 9 , Downstream of the first turbine 11 is an exhaust gas cleaning unit 19 arranged to purify the exhaust gas and reduce pollutant emissions, which is exemplified in the form of a catalyst and particle filter.

For loading the emission control unit as required 19 this has a heating level 20 on, which is in the form of an electrically assisted, in other words electrically heatable catalyst. The first compressor 15 is independent of its drive using the first turbine 11 electrically driven. In other words, that means the first compressor 15 is supported electrically and by an electric motor M is driven.

The exhaust tract 7 has a single exhaust gas turbocharger 12 which, for use over an entire operating range of the internal combustion engine 1 large mass throughputs permitted both on the turbine and on the compressor side. However, this means that due to a high moment of inertia of a running gear of the exhaust gas turbocharger 12 with low mass flow rates on the turbine side, in particular in the low speed and / or load range of the internal combustion engine 1 the amount of air required for producing a high torque for the internal combustion engine 1 cannot be funded.

To promote the desired amount of air, especially in the lower load and / or speed range of the internal combustion engine 1 is the electrically driven compressor 15 intended. This can be operated as required due to its electrical support. The advantage of this embodiment is a reduction in heat loss in the exhaust system 7 compared to two smaller turbochargers.

The in the above-described embodiments of the internal combustion engine according to the invention 1 respectively. of the exhaust tract according to the invention 7 shown exhaust gas turbocharger 12 . 14 are, unless otherwise described, in the form of so-called wastegate loaders with a bypass valve 17 educated. They could also be designed as exhaust gas turbochargers without the possibility of bypassing their turbine wheels or with an adjustable turbine geometry.

The emission control unit 19 is exemplified as a combination of a catalyst and a particle filter. It could just as well be designed in the form of a catalyst or a pure particle filter. The catalytic converter can be designed, for example, in the form of a three-way catalytic converter or a so-called SCR catalytic converter for the selective catalytic reaction or an NO _x storage catalytic converter. The particle filter can also be designed in various forms.

Of course, the number of cylinders 3 the internal combustion engine 1 not limited to the number given as an example. In other words, that means the internal combustion engine 1 For example, only two cylinders 3 could have or it could have sixteen cylinders 3 exhibit. Likewise, the arrangement of the cylinders 3 be designed in the form of a so-called in-line engine or in the form of a V-engine.

LIST OF REFERENCE NUMBERS

1

Internal combustion engine

2

First cylinder bank

3

cylinder

4

Second cylinder bank

5

First exhaust manifold

6

Second exhaust manifold

7

exhaust tract

8th

exhaust port

9

First exhaust pipe

10

Second exhaust pipe

11

First turbine

12

First exhaust gas turbocharger

13

Second turbine

14

Second exhaust gas turbocharger

15

First compressor

16

Second compressor

17

bypass valve

18

Third exhaust pipe

19

exhaust gas cleaning unit

20

heating stage

21

First confluence

22

Second confluence

23

Third compressor

24

Valve

M

engine

QUOTES INCLUDE IN THE DESCRIPTION

This list of documents listed by the applicant has been generated automatically and is only included for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 10015291 A1 [0004]
• DE 102007037087 A1 [0005]
• DE 102009006359 A1 [0005]
• EP 2402576 B1 [0005]
• US 2010/0071365 A1 [0006]
• EP 1640598 A1 [0006]

Claims (8)

Exhaust tract for an internal combustion engine, comprising at least one exhaust manifold (5; 6), the exhaust manifold (5; 6) being designed so that cylinders (3) of the internal combustion engine (1) can flow through it, and with a flowable exhaust pipe (9; 10), wherein in the exhaust gas line (9; 10) has a turbine (11; 13) of an exhaust gas turbocharger (12; 14) received through it, and downstream of the exhaust gas turbocharger (12; 14) an exhaust gas cleaning unit (19) is received through the exhaust tract (7), and The exhaust tract (7) for guiding the exhaust gas of the exhaust gas of the internal combustion engine (1) from the exhaust manifolds (5, 6) into the exhaust gas cleaning unit (19) so that it can be flowed through, characterized in that a heating stage (20 ) is provided. Exhaust tract after Claim 1 , characterized in that the heating level (20) is adjustable. Exhaust tract after Claim 1 or 2 , characterized in that an electrically and / or mechanically drivable compressor (15; 23) is received upstream of the exhaust gas cleaning unit (19) in the exhaust tract (7). Exhaust tract according to one of the preceding claims, characterized in that an adjustable turbine geometry is formed in the exhaust tract (7). Exhaust tract according to one of the preceding claims, characterized in that at least one exhaust gas turbocharger (12; 14) has a turbine wheel around which flow can flow. Exhaust tract according to one of the preceding claims, characterized in that at least one control valve (24) is provided in the exhaust tract (7). Internal combustion engine with an exhaust tract according to one of the Claims 1 to 6 , Internal combustion engine after Claim 7 , characterized in that the internal combustion engine (1) has at least two independently configured exhaust manifolds (5, 6).

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