DE102015208360A1 - motor vehicle - Google Patents

Abstract

The invention relates to a motor vehicle (2) comprising an internal combustion engine (4), an exhaust system (12) and an engine cooling circuit (6) for cooling the internal combustion engine (4), wherein the engine cooling circuit (6) has an engine radiator (10) which is in operation is traversed by an engine coolant and wherein the motor vehicle (2) comprises an exhaust gas duct cooling circuit (14) for cooling the exhaust gas duct (12) with a heat exchanger (18, 38) and with a cooler unit (20), which in operation of a second coolant , the exhaust gas routing coolant, is flowed through.

Description

The invention relates to a motor vehicle comprising an internal combustion engine, an exhaust system and an engine cooling circuit for cooling the internal combustion engine, wherein the engine cooling circuit comprises an engine radiator, which is flowed through during operation of an engine coolant.

Motor vehicles of the latest generation generally have several modules or functional units that generate waste heat during operation and to protect against overheating either active, usually by means of a cooling circuit, or passive, typically favored by the wind, cooled. Here, the modules or the functional units often differ, inter alia, in terms of their waste heat characteristics, which is why sometimes several active cooling devices are used in a motor vehicle, which are designed for different temperature ranges and / or specially adapted to different modules.

Thus, for example, a so-called high-temperature cooling circuit is used for cooling an internal combustion engine, which is typically operated at temperatures in the range of 90 ° C to 125 ° C during operation. The cooling of electronic assemblies and / or an electric drive system with an electric motor, however, is usually carried out by means of a so-called low-temperature cooling circuit, which usually has an operating temperature window in the range of 55 ° C to 85 ° C. In addition, as a rule, the operating pressures of cooling circuits also differ and frequently also different coolants or coolant mixtures are used. Thus, during normal operation, ie in the warm state, the high-temperature cooling circuit typically has an overpressure of approximately 1 to 2 bar, whereas the low-temperature cooling circuit only has an overpressure of, for example, a few 100 mbar.

The structural elements of an exhaust system of a motor vehicle are usually passive, favored cooled by the wind. However, in some cases, for example, when a turbocharger driven by the exhaust gas flow is integrated into the exhaust passage, the cooling performance of such passive cooling is not sufficient in all operating conditions, which is why so-called enrichment of the combustion mixture with fuel is sometimes performed at high load conditions Way the exhaust system, so in particular the turbocharger to protect against overheating.

Proceeding from this, the present invention seeks to provide a motor vehicle in which the exhaust system is advantageously protected against overheating.

This object is achieved by a motor vehicle having the features of claim 1. Preferred developments are contained in the dependent claims.

A corresponding motor vehicle in this case comprises an internal combustion engine and an engine cooling circuit for cooling the internal combustion engine with an engine radiator, which is traversed by an engine coolant during operation. In addition, the motor vehicle comprises an exhaust system for the exhaust gases of the internal combustion engine and an exhaust gas duct cooling circuit for cooling the exhaust system with at least one heat exchanger and at least one radiator unit, which is flowed through in operation by a second coolant, the exhaust gas routing coolant.

In the motor vehicle, an active cooling device for the exhaust system is thus realized by the exhaust gas duct cooling circuit, which is either permanently active during operation of the engine or switched on as needed, so that sufficient cooling of the exhaust system is ensured in each operating situation. On the above-described usual enrichment of the combustion mixture for the internal combustion engine can thus be dispensed with, which on the one hand leads to lower fuel consumption and on the other hand improves the emission characteristics of the motor vehicle.

In addition, the two cooling circuits of the motor vehicle are separated from each other by coolant technology, whereby they are, inter alia, independently operable and / or independently adaptable to their respective tasks. In addition, a separate cooler or a separate cooling unit is provided for each cooling circuit through which the waste heat is discharged into the environment, whereby it is possible to actively cool the exhaust system, without thereby burdening the engine cooling circuit.

The possibility of adapting the two cooling circuits to their individual tasks is preferably used to design the two cooling circuits for different temperature ranges. The engine cooling circuit is expediently designed as a high-temperature cooling circuit of the aforementioned type, whereas the exhaust gas duct cooling circuit is preferably designed for a maximum temperature of the exhaust gas routing coolant greater than 130 ° C and especially greater than 200 ° C. An operating temperature of the exhaust gas routing coolant in the range from 140 ° C. to 250 ° C. or even in the range from 300 ° C. to 400 ° C. is typical.

In this case, the exhaust gas duct cooling circuit is tended to be designed for the typical temperatures of the exhaust gas flow immediately after leaving the internal combustion engine, whereby it is possible, for example, to directly thermally couple the exhaust gas duct cooling circuit to the exhaust gas flow.

In particular, in the cases where the exhaust gas routing cooling circuit is designed for such temperatures, different operating pressures are provided for the two cooling circuits. According to one embodiment, an operating pressure greater than 3 bar and in particular greater than 50 bar is given for the exhaust gas duct cooling circuit, in order to use a simple water-glycol mixture as exhaust gas routing coolant, even if the exhaust gas duct cooling circuit for a maximum temperature is greater than 130 ° C.

As an alternative to a water-glycol mixture, a water / antifreeze mixture with increased temperature resistance, a thermal oil, a salt, a liquid metal or a liquid metal mixture, for example eutectic NaK, are optionally used as the exhaust gas routing coolant. These offer, inter alia, the advantage that when using a lower operating pressure for the exhaust gas duct cooling circuit can be specified.

The at least one heat exchanger of the exhaust gas duct cooling circuit serves for the thermal coupling of the exhaust gas duct cooling circuit with the exhaust gas duct or directly with the exhaust gas flow in the exhaust duct, which likewise results in a reduction in the temperature of the structural elements of the exhaust duct. For a direct extraction of heat from the exhaust gas flow, the at least one heat exchanger is expediently positioned in the exhaust gas guide, so that it flows around and / or flows through the exhaust gas during operation, whereas for thermal coupling to the exhaust gas duct the design of the at least one heat exchanger is typically selected such that that this is applied to structural elements of the exhaust system in particular a large area. It is advantageous if the at least one heat exchanger is formed by a jacket of the exhaust system or a part of the exhaust system or at least in the manner of a sheath, which is then expediently flows through during operation of the exhaust gas routing coolant. Such a jacket is typically applied directly to structural elements of the exhaust system.

Irrespective of this, the at least one heat exchanger is designed, for example, as a tubular heat exchanger, as a plate heat exchanger or as a so-called microchannel heat exchanger, the actual configuration being expediently adapted to the respective intended use.

The circulation of the exhaust gas routing coolant in the exhaust gas routing cooling circuit is further accomplished by means of a conveyor which is optionally designed as a radial impeller pump, a gear pump, as a friction pump, as a pulse pump, as a jet pump or as an electromagnetic pump.

It is favorable, furthermore, if the exhaust gas routing cooling circuit is kept simple, for example by the fact that only particularly critical parts or sections of the exhaust gas guide are coupled to the exhaust gas routing cooling circuit. Thus, instead of actively cooling the entire exhaust gas duct over the entire length by means of the at least one heat exchanger or by means of a plurality of heat exchangers, such active cooling is preferably carried out only in individual sections or a single section of the exhaust system, for example in the region of an exhaust manifold of the exhaust system or in the range of a catalyst in the exhaust system.

The exhaust gas directly, ie via at least one heat exchanger to the structural elements of the exhaust system, and / or indirectly, ie by direct cooling of the exhaust gas flow through at least one heat exchanger in the exhaust stream, extracted heat is subsequently driven by a pump in the exhaust gas duct cooling circuit to the radiator unit of the exhaust system Cooling circuit out and delivered there at least partially to the environment of the motor vehicle. The cooling of the cooler unit is preferably passive, ie without the use of a fan or fan, but favored by an air flow, which is caused by the so-called wind. The cooler unit is in this case further preferably positioned outside of the so-called front cooler, which typically comprises a plurality of cooler or cooler units, but at least the engine radiator.

It is advantageous in this case to arrange the cooler unit of the exhaust gas routing cooling circuit in the so-called underfloor area of the motor vehicle, that is to say for example in the area of a so-called underbody or in the area of the so-called wheel arches.

Regardless of the position of the radiator unit, it is further favorable if the radiator unit of the exhaust-gas cooling circuit forms a part of a motor vehicle outer skin, in particular with a permissible wall temperature greater than 80 ° C., since this makes it possible to realize a very effective air inflow for the radiator unit, without that thereby the flow behavior unfavorable being affected. It should be noted that the flow characteristics of a motor vehicle, so the way the motor vehicle is surrounded by the ambient air while driving, on the one hand determines the fuel consumption and on the other hand, the driving stability of the motor vehicle at high speeds.

As already mentioned, the positioning of the cooler unit preferably takes place in the underfloor region, so that the cooler unit, if it also forms an automobile outer skin, preferably forms part of an underbody paneling. This is particularly advantageous when the outer skin forming surface of the radiator unit reaches relatively high temperatures during operation, which could lead to injury if touched.

It is also advantageous to design the cooler unit as a plate-shaped cooler or heat exchanger, wherein this further preferably has a longitudinal ribbing extending in the direction of flow at least on a side facing the surroundings of the motor vehicle. In this case, the corresponding longitudinal ribs increase the surface of the cooling unit which flows in driving operation, thereby increasing the cooling efficiency. The direction of flow here means the local direction of the air flow on the outside of the cooling unit caused by the so-called airstream.

In an advantageous embodiment, the heat removed from the exhaust gas stream or the structural elements of the exhaust gas duct is not simply released into the environment, but instead is used at least partially with the aid of a waste heat recovery system as useful heat or thermal drive energy. For this purpose, a corresponding exhaust gas utilization system is integrated into the exhaust gas duct cooling circuit, wherein the exhaust gas duct cooling circuit, even in such a design variant, preferably primarily serves to ensure sufficient cooling for the exhaust gas duct. Depending on the nature of the waste heat recovery system and depending on the way the integration of the waste heat recovery system in the exhaust gas circulation this is therefore preferably designed such that the waste heat recovery system can be bypassed if necessary, for example via a bypass, if a higher cooling demand and a bypass of the waste heat recovery system a higher cooling capacity due to the exhaust gas circulation cooling circuit.

According to a simple embodiment, the waste heat recovery system is designed as a simple heat storage and in particular as latent heat storage, which is then used, for example, at the next startup of the internal combustion engine of the motor vehicle to preheat the internal combustion engine and / or the passenger compartment of the motor vehicle by means of the heat stored therein.

Alternatively, the waste heat recovery system as a thermoelectric generator (TEG) or as a so-called evaporation device (turbo starter) or as a sorption, for example in the manner of a thermal cycler formed. If a corresponding sorption system is to be used, it is further preferably designed as an adsorption system and expediently also designed for operation as a heat pump and / or refrigeration machine.

The principle can be easily transferred to several such waste heat recovery systems and accordingly, depending on the application, several of the aforementioned waste heat recovery systems are integrated into the exhaust gas duct cooling circuit. These can then preferably be switched on independently or bypass each other, in order to ensure sufficient cooling of the exhaust system in this way during operation in any operating situation.

The introduction of a corresponding waste heat recovery system is carried out according to a variant such that the exhaust gas cooling coolant during operation on its way through the exhaust gas duct cooling circuit, the waste heat recovery system once before entering the radiator unit of the exhaust duct cooling circuit and once after exiting the radiator unit of Abgasführungs- Cooling circuit flows through. In this way, a relatively high temperature difference between two heat reservoirs can be generated in the waste heat recovery system, which is particularly favorable for the operation of a heat pump or a refrigeration machine.

According to an alternative embodiment, the exhaust gas routing cooling circuit is divided into two subcircuits which are at least temporarily separated by coolant technology, the first subcircuit comprising the at least one heat exchanger, the second subcircuit comprising the cooler unit of the exhaust gas routing cooling circuit and the two subcircuits being thermally connected to one another by the waste heat utilization system are coupled. In this embodiment, a separate conveyor, ie a separate pump, is then expediently provided for each partial circuit. In addition, such a ausgestalteteter exhaust duct cooling circuit preferably has two bypasses, which are either flowed through during operation permanently by the exhaust gas routing coolant or can be unlocked via valves if necessary, in particular in this way, if necessary, the Waste heat recovery system to increase the cooling capacity of the exhaust gas circulation cooling circuit to bypass.

A corresponding waste heat utilization system can then be advantageously used in the motor vehicle in various ways. Thus, a sorption plant can in principle be used as a heat pump and / or as a chiller, which can be used for example as a replacement for a classic air conditioning with air conditioning compressor. In this case can then be dispensed with a conventional refrigerant, for example R134a, R1234y, R744, which is perceived especially in the public as environmentally harmful and / or dangerous. Next can be with a corresponding waste heat recovery system, at least if this is used as a heat storage or as latent heat storage, realize a so-called auxiliary heating, with the help of the internal combustion engine, the transmission and / or the passenger compartment can be preheated prior to commissioning of the motor vehicle or , Furthermore, by using a corresponding waste heat utilization system, covering surfaces in the interior of the motor vehicle, for example parts of the door inner lining, the armrest layers, the cockpit cover, the headliner or operating elements, such as the steering wheel, can be cooled or heated as required, which in turn increases comfort ,

Embodiments of the invention will be explained in more detail with reference to a schematic drawing. Show:

1 in a side view of a motor vehicle with an exhaust gas routing cooling circuit,

2 in a plan view, the underside of the motor vehicle with the exhaust gas routing cooling circuit,

3 in a block diagram, a first alternative embodiment of the exhaust gas duct cooling circuit and

4 in a block diagram, a second alternative embodiment of the exhaust gas duct cooling circuit.

Corresponding parts are provided in all figures with the same reference numerals.

An example described below and in 1 such as 2 indicated motor vehicle 2 includes an internal combustion engine 4 operating by means of an engine cooling circuit 6 is cooled. In that engine cooling circuit 6 circulated in this case driven by a pump 8th an engine coolant, which heat in the internal combustion engine 4 picks up and over a radiator 10 to the environment of the motor vehicle 2 at least partially surrenders. The engine cooler 10 is here in the front of the vehicle 2 positioned and thereby designed as a so-called front cooler.

The from the combustion engine 4 exhaust gases generated during operation are referred to as exhaust gas flow via an exhaust system 12 dissipated, consisting of several assemblies, including an exhaust manifold 12A and a catalyst 12B , is constructed. This will be the exhaust manifold 12A and the catalyst 12B during operation of the motor vehicle 2 for protection against overheating by means of an exhaust gas routing cooling circuit 14 actively cooled by being driven by its own pump 16 an exhaust gas routing coolant circulates. The exhaust gas circulation cooling circuit 14 and the engine cooling circuit 6 are thus separated in the embodiment not only by coolant technology, but completely decoupled, so that they can be operated independently. In this case, the exhaust gas routing cooling circuit 14 also own heat exchanger for receiving and for the delivery of heat, in particular spatially from the corresponding heat exchangers of the engine cooling circuit 6 gentrennt are arranged.

The two transmit heat to the exhaust gas routing coolant of the exhaust gas routing cooling circuit 14 used heat exchangers are as shell heat exchanger 18 one of which is the exhaust manifold 12A encased and one the catalyst 12B , This is the shell heat exchanger 18 at the corresponding structural elements of the exhaust system 12 , so the exhaust manifold 12A on the one hand and the catalyst 12B on the other hand, over a large area and are flowed through during operation of the exhaust gas routing coolant.

The in the shell heat exchanger 18 absorbed heat continues with the help of two cooling units 20 at least partially to the environment of the motor vehicle 2 issued. The two cooling units 20 are designed as passive, plate-shaped heat exchanger without its own fan or fan and in the area of a subfloor 22 in the underfloor area of the motor vehicle 2 arranged. While driving the motor vehicle 2 become the cooling units 20 then by an air flow in the flow direction 24 flows and flows around, which is caused by the so-called wind.

To increase the surface of the cooling units 20 have this continue in the flow direction 24 extending longitudinal ribs 26 on and the environment of the motor vehicle 2 facing surfaces of the cooling units 20 Make up a part of the subfloor that looks like a disguise or cover the motor vehicle 2 closes at the bottom.

A second embodiment is in 3 shown schematically. Here are in the exhaust gas duct cooling circuit 14 additionally integrated two waste heat recovery systems, with the help of which the exhaust system 12 or the exhaust gas flow extracted waste heat is at least partially used as useful heat.

The first waste heat recovery system comprises an additional heat exchanger 30 as well as a valve 32 , Will the valve 32 opened, then flows through the exhaust gas coolant in the sequence the additional heat exchanger 30 , About the part of the heat from the exhaust gas circulation cooling circuit to the passenger compartment of the motor vehicle 2 for heating it is delivered. When the valve is closed 32 however, the exhaust gas routing coolant does not become active over or through the auxiliary heat exchanger 30 guided.

The second waste heat recovery system is as Adsorptionsanlage 28 designed and can be operated as needed as a heat pump or chiller. The for the operation of the adsorption plant 28 required heat source and heat sink is realized in the embodiment, by the exhaust gas duct cooling circuit 14 in two subcircuits 34 . 36 is split, with the first subcircuit 34 a single-inlet heat exchanger 38 that is in the exhaust system 12 rests and during operation of the exhaust stream of the internal combustion engine 4 is streamed and flows around. The heat exchanger provided for the heat exchanger of the exhaust gas duct cooling circuit 14 is thus part of the first cooling circuit 34 , The heat exchanger provided to the environment heat exchanger, however, is part of the second partial circuit 36 and configured as in the embodiment described above in the manner of a plate cooler, wherein this plate-shaped cooling unit 20 again in the underfloor area of the motor vehicle 2 is arranged.

In standard operation, the two subcircuits are 34 . 36 both coolant and thermally separated from each other, creating a very effective operation of the adsorption 28 is possible. Is the cooling capacity of the exhaust gas circulation cooling circuit 14 In standard mode, this is no longer sufficient, so two bypass valves are automatically activated 40 opened, so that in the sequence the two subcircuits 34 . 36 Coolant technology are interconnected and a large part of the exhaust gas routing coolant via bypass lines 42 at the adsorption plant 28 is passed. By this bypass the adsorption 28 can the cooling capacity of the exhaust gas circulation cooling circuit 14 increase and sufficient cooling of the exhaust system 12 to ensure.

In this high-performance cooling operation, in which the two subcircuits 34 . 36 coupled, the circulation of the exhaust gas routing coolant alone with a base pump 44 maintained. However, as soon as the lock-up valves 40 closed for standard operation, is also an additional pump 46 activated so that in each subcircuit 34 . 36 a separate pump is active.

According to a further embodiment is in the exhaust gas duct cooling circuit 14 only a waste heat recovery system integrated, which serves as a sorption 48 is designed. The sorption plant 48 is in such a way in the exhaust gas duct cooling circuit 14 Integrated that the exhaust gas routing coolant circulates on its way through the exhaust gas duct cooling circuit 14 the waste heat recovery system once before entering the cooler unit 20 and once after exiting the cooler unit 20 flows through. This situation is in 4 indicated.

The invention is not limited to the embodiment described above. Rather, other variants of the invention can be derived therefrom by the person skilled in the art without departing from the subject matter of the invention. In particular, all the individual features described in connection with the exemplary embodiment can also be combined with each other in other ways, without departing from the subject matter of the invention.

LIST OF REFERENCE NUMBERS

2

motor vehicle

4

internal combustion engine

6

Engine cooling circuit

8th

pump

10

radiator

12

exhaust system

12A

exhaust manifold

12B

catalyst

14

Exhaust guide cooling circuit

16

pump

18

Sheath heat exchanger

20

cooler unit

22

underbody

24

flow direction

26

longitudinal ribs

28

adsorption

30

Additional heat exchanger

32

Valve

34

first partial cycle

36

second subcircuit

38

Einliege heat exchanger

40

bypass valve

42

bypass line

44

basic pump

46

additional pump

48

sorption

Claims (16)

Motor vehicle ( 2 ) comprising an internal combustion engine ( 4 ), an exhaust system ( 12 ) and an engine cooling circuit ( 6 ) for cooling the internal combustion engine ( 4 ), wherein the engine cooling circuit ( 6 ) a radiator ( 10 ), which is flowed through during operation of an engine coolant, characterized in that this an exhaust gas routing cooling circuit ( 14 ) for cooling the exhaust system ( 12 ) having a heat exchanger ( 18 . 38 ) and with a cooler unit ( 20 ), which is flowed through in operation by a second coolant, the exhaust gas routing coolant. Motor vehicle ( 2 ) according to claim 1, characterized in that the exhaust gas routing cooling circuit ( 14 ) is designed for a maximum temperature of the exhaust gas routing coolant greater than 130 ° C and in particular greater than 200 ° C. Motor vehicle ( 2 ) according to claim 1 or 2, characterized in that a water-glycol mixture is used as exhaust gas routing coolant and that the exhaust gas routing cooling circuit ( 14 ) is designed for an operating pressure greater than 3 bar and in particular greater than 50 bar. Motor vehicle ( 2 ) according to one of claims 1 to 2, characterized in that as exhaust gas routing coolant either a water-antifreeze mixture, a thermal oil, a salt, a liquid metal or a liquid metal mixture is used. Motor vehicle ( 2 ) according to one of claims 1 to 4, characterized in that the heat exchanger ( 38 ) of the exhaust gas routing cooling circuit ( 14 ) during operation of the internal combustion engine ( 4 ) directly with the exhaust gas flow in the exhaust system ( 12 ) is in contact. Motor vehicle ( 2 ) according to one of claims 1 to 5, characterized in that the exhaust system ( 12 ) an exhaust manifold ( 12A ) and that the heat exchanger ( 18 . 38 ) in the region of the exhaust manifold ( 12A ) is positioned. Motor vehicle ( 2 ) according to one of claims 1 to 6, characterized in that the exhaust system ( 12 ) a catalyst ( 12B ) and that the heat exchanger ( 18 . 38 ) in the region of the catalyst ( 12B ) is positioned. Motor vehicle ( 2 ) according to one of claims 1 to 7, characterized in that the cooler unit ( 20 ) of the exhaust gas routing cooling circuit ( 14 ) in the underfloor area ( 22 ) is arranged. Motor vehicle ( 2 ) according to one of claims 1 to 8, characterized in that the cooler unit ( 20 ) of the exhaust gas routing cooling circuit ( 14 ) a part of a motor vehicle outer skin ( 22 ) and in particular a subfloor lining ( 22 ) trains. Motor vehicle ( 2 ) according to one of claims 1 to 9, characterized in that the cooler unit ( 20 ) of the exhaust gas routing cooling circuit ( 14 ) as in the flow direction ( 24 ) longitudinally finned plate cooler ( 20 . 26 ) is trained. Motor vehicle ( 2 ) according to one of claims 1 to 10, characterized in that in the exhaust gas duct cooling circuit ( 14 ) a waste heat recovery system ( 28 . 30 . 48 ) is integrated. Motor vehicle ( 2 ) according to one of claims 1 to 11, characterized in that in the exhaust gas duct cooling circuit ( 14 ) Latent heat storage is integrated. Motor vehicle ( 2 ) according to one of claims 1 to 12, characterized in that in the exhaust gas duct cooling circuit ( 14 ) a sorption plant ( 48 ), in particular an adsorption plant ( 28 ) is integrated. Motor vehicle ( 2 ) according to one of claims 1 to 13, characterized in that in the exhaust gas duct cooling circuit ( 14 ) a waste heat recovery system ( 28 . 30 . 48 ) and that the exhaust gas routing coolant in operation on its way through the exhaust gas circulation cooling circuit ( 14 ) the waste heat utilization system ( 28 . 30 . 48 ) once before entering the cooler unit ( 20 ) of the exhaust gas routing cooling circuit ( 14 ) and once after exiting the cooler unit ( 20 ) of the exhaust gas routing cooling circuit ( 14 ) flows through. Motor vehicle ( 2 ) according to one of claims 1 to 13, characterized in that in the Exhaust gas routing cooling circuit ( 14 ) a waste heat recovery system ( 28 . 30 . 48 ) is integrated, that the exhaust gas circulation cooling circuit ( 14 ) is divided into two subcircuits separated from one another, at least temporarily, by means of coolant technology, wherein the first subcircuit ( 34 ) the at least one heat exchanger ( 38 ) and wherein the second subcircuit ( 36 ) the cooler unit ( 20 ) of the exhaust gas routing cooling circuit ( 14 ), and that the two subcircuits ( 34 . 36 ) by the waste heat utilization system ( 28 . 30 . 48 ) are thermally coupled together. Motor vehicle ( 2 ) according to one of claims 1 to 15, characterized in that in the exhaust gas routing cooling circuit ( 14 ) a waste heat recovery system ( 28 . 30 . 48 ), at least one bypass line ( 42 ) and at least one bypass valve ( 40 ) and that the exhaust gas circulation cooling circuit ( 14 ) is configured such that at least a portion of the exhaust gas routing coolant in operation, if necessary, bypassing the waste heat recovery system ( 28 . 30 . 48 ) via the at least one bypass line ( 42 ) in the exhaust gas circulation cooling circuit ( 14 ) circulates.

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