DE102014205378A1 - Exhaust system for an internal combustion engine - Google Patents

Abstract

Exhaust system for an internal combustion engine, with a arranged in an exhaust pipe exhaust gas countercurrent heat exchanger, which is connected via a first exhaust pipe section exhaust leading to the internal combustion engine, wherein a first volume of the exhaust gas countercurrent heat exchanger with exhaust gas of the internal combustion engine can be flowed through and the exhaust gas a second exhaust pipe section and can be flowed through in countercurrent by a second volume of the exhaust gas countercurrent heat exchanger, wherein a heat energy of the exhaust gas flows from the first volume to the second volume, wherein in the second exhaust pipe section, a turbine housing is arranged with a turbine wheel of an exhaust gas turbocharger. The inventive design of the fuel consumption of the internal combustion engine and the thermal load of the components of the exhaust system are reduced.

Description

An internal combustion engine converts, as is well known, only a part of the energy of the fuel into mechanical energy. The other part is discharged essentially as heat loss via the exhaust gas and the cooling to the environment.

In certain operating points of the internal combustion engine, the exhaust gas temperature is too high for some components in the exhaust system, however (eg for the turbine of the turbocharger, for the catalytic converter). For component protection, it is therefore necessary to reduce the temperature of the exhaust gas. This is currently z. B. by enrichment of the air / fuel mixture (cooling by the evaporation of existing in the exhaust, unburned fuel). If this is not possible or undesirable for environmental reasons, the exhaust gas can be cooled directly by coupling the cooling system to the exhaust manifold of the internal combustion engine (cooling water exhaust gas heat exchanger). This leads disadvantageously to a considerable, additional heat input into the cooling circuit. If necessary, this leads to a larger cooling system, in particular larger heat exchangers, with the corresponding disadvantage of higher costs, weight, etc.

The technical environment, for example, the German patent application DE 10 2007 040 793 A1 indicated, from which a heat exchanger, in particular an exhaust gas heat exchanger, is known. In this case, there is a heat exchange between the exhaust gas and a second fluid, in particular a coolant instead. The exhaust gas flows through flow channels. These open into a housing, which is flowed through by the second fluid. The central goal here is, inter alia, the direct or indirect cooling of exhaust gas in an exhaust gas recirculation system of an internal combustion engine.

Furthermore, from the German patent application DE 10 2009 050 888 A1 a heat exchanger, also an exhaust gas heat exchanger known. The exhaust gas is directed into pipes (flow channels). Between these and the housing, a second flow channel is formed through which a second fluid, in particular a cooling liquid is passed through. The heat exchanger also serves primarily for the return and cooling of exhaust gases of an internal combustion engine, in particular a diesel engine.

Next is from the European patent application EP 1 985 953 A1 an exhaust gas countercurrent heat exchanger, in particular from 8th , known. This is a two-stage exhaust gas heat exchanger with a so-called U-flow (counterflow). This exhaust gas countercurrent heat exchanger has an extremely efficient heat dissipation.

This known prior art leads in part to high component loads, in particular thermal component loads for the turbocharger and the catalyst. This requires on the one hand a lower durability, so that more expensive materials are required for a longer life. In addition, results from the prior art, insufficient cooling. Disadvantageously, the known state of the art also leads to power losses of the internal combustion engine, or as stated above, to an increased fuel consumption.

The object of the present invention is to avoid the abovementioned disadvantages.

This object is solved by the features in the characterizing part of patent claim 1.

The basic object of the invention is to thermally protect the thermally sensitive components, such as the exhaust gas turbocharger and the catalyst by cooling by the heat energy of the hot exhaust gas is not transferred to the cooling system of the internal combustion engine, but at least partially left in the exhaust. This is inventively achieved in that the exhaust gas heat exchanger is designed as an exhaust gas countercurrent heat exchanger. As a result, the exhaust gas flowing out of the internal combustion engine transfers its heat energy only partially into the turbocharger and the catalyst and the other part into the exhaust gas flowing out. The cooling water exhaust gas heat exchanger can thus be advantageously reduced in size. The heat released into the cooling water of the internal combustion engine decreases.

Depending on the configuration of the exhaust gas countercurrent heat exchanger, the dimensions of the cooling water exhaust gas heat exchanger drop significantly. Ideally, this will only control the temperature of the exhaust gas at the turbocharger or the catalyst and the main amount of heat is transferred in the exhaust gas countercurrent heat exchanger to the effluent exhaust gas. The heat loss thus leaves the vehicle via the exhaust, without the need for a significantly enlarged or additional water heat exchanger. A significant increase in weight is thus avoided in an advantageous manner. Further, an increase in weight of the exhaust gas turbocharger is avoided and the efficiency of the exhaust gas turbocharger, in particular the exhaust gas turbine, is additionally increased by a low thermal component load in a comparable operating point of the internal combustion engine. As a result, the turbocharger cover a wider range of applications and the connection of a waste gate, to avoid thermal overheating of the components, takes place at a higher operating point. It can thus In addition, a higher engine power of the internal combustion engine can be achieved.

The embodiment according to claim 1 is the simplest embodiment of an exhaust system for an internal combustion engine, with which the above-mentioned advantageous effects are achieved.

With the embodiment according to claim 2, the thermal load of the exhaust gas turbocharger can be further reduced.

The embodiment according to claim 3 is a preferred embodiment in which the catalyst very quickly reaches its light-off temperature (the temperature at which the catalyst reaches its conversion temperature). A warm-up phase of the internal combustion engine is thus significantly shortened.

The invention is explained in more detail below with reference to a schematic representation in a single figure.

1 shows a schematic representation of an exhaust system according to the invention for an internal combustion engine.

1 schematically shows an exhaust system according to the invention for an internal combustion engine 1 , From the internal combustion engine 1 an exhaust gas flows into an exhaust pipe 2 , which consists of a first exhaust pipe section 2a , a second exhaust pipe section 2 B , and a third exhaust pipe section 2c consists. First, the exhaust gas flows into an exhaust gas countercurrent heat exchanger 3 by taking heat energy from a first volume 3a in a second volume 3b flows.

Further, in this embodiment, the exhaust gas flows through the second exhaust pipe section 2a in a coolant-exhaust heat exchanger 5 , There superfluous heat energy or amount of heat is transferred into a coolant of the internal combustion engine. By this cooling of the exhaust gas is a good protection of the exhaust gas turbocharger 4 given against overheating.

Further, the exhaust gas flows through the second exhaust pipe section 2 B in a turbine housing 4 an exhaust gas turbocharger by an unillustrated turbine wheel is driven.

After the turbine housing 4 the exhaust gas continues to flow through a second exhaust pipe section 2 B in an emission control system 6 , for example, a catalyst. After the emission control system 6 in turn, the exhaust gas continues to flow through the second exhaust pipe section 2 B in the exhaust gas countercurrent heat exchanger 3 , in the second volume 3b where the now cooled exhaust gas is reheated. Subsequently, the reheated exhaust gas leaves the exhaust system through the third exhaust pipe section 2c ,

In the presented inventive embodiment of the exhaust system for an internal combustion engine 1 the goal is achieved to protect the thermally sensitive components by cooling and yet not transfer the heat energy into the cooling system of the internal combustion engine, but at least partially recirculate the exhaust gas. This is achieved by the fact that the heat exchanger 3 designed as an exhaust gas countercurrent heat exchanger. That from the internal combustion engine 1 Outgoing exhaust gas thereby passes a portion of its heat energy before flowing through the turbocharger and the catalyst to the effluent exhaust gas. The cooling water exhaust heat exchanger 5 can be downsized. The amount of heat released into the cooling water drops. Depending on the design of the exhaust gas countercurrent heat exchanger 3 decrease the dimensions of the cooling water exhaust heat exchanger 5 clear. Ideally, with it only the temperature of the exhaust gas in front of the turbocharger and the catalyst 6 regulated and the main heat quantity is in the exhaust gas countercurrent heat exchanger 3 to hand over. The heat loss thus leaves the vehicle via the exhaust, without the need for a significantly enlarged or additional water heat exchanger. A significant increase in weight is thus avoided and the efficiency of the exhaust gas turbocharger, in particular the exhaust gas turbine 4 , is additionally increased by a low component load in a comparable operating point. This allows the turbocharger cover a wider range of applications and the connection of a wastegate, to avoid thermal overheating of the components, takes place at a later operating point. It can thus additionally a higher engine power of the internal combustion engine 1 be achieved.

LIST OF REFERENCE NUMBERS

1

Internal combustion engine

2

exhaust pipe

2a

first exhaust pipe section

2 B

second exhaust pipe section

2c

third exhaust pipe section

3

Exhaust gas counter-current heat exchanger

3a

first volume

3b

second volume

4

turbine housing

5

Coolant exhaust gas heat exchanger

6

emission control system

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely 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.

Cited patent literature

• DE 102007040793 A1 [0003]
• DE 102009050888 A1 [0004]
• EP 1985953 A1 [0005]

Claims (3)

Exhaust system for an internal combustion engine ( 1 ), with one in an exhaust pipe ( 2 ) arranged exhaust gas countercurrent heat exchanger ( 3 ), which via a first exhaust pipe section ( 2a ) Exhaust leading to the internal combustion engine ( 1 ), wherein a first volume ( 3a ) of the exhaust gas countercurrent heat exchanger ( 3 ) with exhaust gas of the internal combustion engine ( 1 ) is flowed through and the exhaust gas through a second exhaust pipe section ( 2 B ) and by a second volume ( 3b ) of the exhaust gas countercurrent heat exchanger ( 3 ) is flowed through in countercurrent, wherein a heat energy of the exhaust gas from the first volume ( 3a ) to the second volume ( 3b ) flows, characterized in that in the second exhaust pipe section ( 2 B ) a turbine housing ( 4 ) is arranged with a turbine wheel of an exhaust gas turbocharger. Exhaust system according to claim 1, characterized in that in the second exhaust pipe section ( 2 B ) between the first volume ( 3a ) and the turbine housing ( 4 ) a coolant-exhaust gas heat exchanger ( 5 ) is arranged. Exhaust system according to claim 1 or 2, characterized in that in the second exhaust pipe section ( 2 B ) between the turbine housing ( 4 ) and the second volume ( 3b ) an emission control system ( 6 ) is arranged.

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