DE102013020401A1 - Method for operating an internal combustion engine of a motor vehicle - Google Patents

Abstract

The invention relates to a method for operating an internal combustion engine (10) of a motor vehicle, in which exhaust gas from at least one first combustion chamber (14) of the internal combustion engine (10) of a first exhaust gas flow (28) fluidically connected to a turbine (32) of an exhaust gas turbocharger (34) ) and exhaust gas from at least one second combustion chamber (22) of the internal combustion engine (10) is supplied to a second exhaust gas flow (30) fluidically connected to the turbine (32) of the exhaust gas turbocharger (34), at which exhaust gas is branched off from the first exhaust gas flow (28) and via a return line (52) in an intake tract (44) of the internal combustion engine (10) is recirculated and in which an exhaust gas flow-through flow cross-section of the first exhaust gas flow (28) is at least partially fluidly blocked, wherein for increasing the temperature of the exhaust gas, a blocking element ( 58), by means of which the flow cross section of the first exhaust gas flow (28) and a flow cross section of the R Return line (52) are adjustable, in a the flow cross section of the return line (52) at least partially releasing and the flow cross section of the first exhaust gas flow (28) at least partially obstructing the open position (2) is moved.

Description

The invention relates to a method for operating an internal combustion engine of a motor vehicle according to the preamble of patent claim 1.

Such a method for operating an internal combustion engine of a motor vehicle is the DE 10 2008 064 264 A1 to be known as known. In the method, exhaust gas from at least one first combustion chamber, in particular in the form of a cylinder, an internal combustion engine is supplied to a first exhaust gas flow fluidically connected to a turbine of an exhaust gas turbocharger. Furthermore, in the method, exhaust gas from at least one second combustion chamber, in particular in the form of a cylinder, is supplied to the internal combustion engine of a second exhaust gas flow which is fluidically connected to the turbine of the exhaust gas turbocharger. This means that the respective exhaust gas flowing through the exhaust gas flows can be supplied to the turbine and drive it.

In the method, exhaust gas is further diverted from the first exhaust gas flow and recycled via a return line into an intake tract of the internal combustion engine. As a result, a low-emission operation of the internal combustion engine can be realized.

In addition, in the method, at least a portion of a flow cross section of the first exhaust gas flow which can be flowed through by the exhaust gas is blocked fluidically. In other words, the first exhaust gas flow, from which exhaust gas is branched off, is also at least partially blocked.

Furthermore, it is known from the general state of the art to arrange an exhaust gas aftertreatment device for treating or aftertreating the exhaust gas of the internal combustion engine in an exhaust tract of an internal combustion engine. Such an exhaust aftertreatment device comprises, for example, at least one catalyst, which may be an oxidation catalytic converter or a nitrogen oxide storage catalytic converter (NO _x storage catalytic converter). As a result, a particularly low-emission operation can be realized.

To realize this low-emission operation, it is necessary for the exhaust-gas aftertreatment device to have a sufficiently high operating temperature, since the exhaust-gas aftertreatment device can treat the exhaust gas efficiently and effectively only at or above this operating temperature.

For example, in order to heat the exhaust aftertreatment device particularly quickly, that is to say in a particularly short time, in order to bring it to operating temperature during a cold start of the internal combustion engine, a particularly high temperature of the exhaust gas flowing through the exhaust gas aftertreatment device is advantageous. Conventionally, a sufficiently high exhaust gas temperature for effecting rapid heating of the exhaust gas aftertreatment device can be realized only with great difficulty, that is, by means of additional actuators and by means of a corresponding method for operating these actuators.

The object of the present invention is therefore to develop a method for operating an internal combustion engine of the type mentioned in such a way that it is possible to realize particularly high exhaust gas temperatures in a particularly simple manner.

This object is achieved by a method having the features of patent claim 1. Advantageous embodiments with expedient and non-trivial developments of the invention are specified in the remaining claims.

In order to further develop a method for operating an internal combustion engine of a motor vehicle, in particular a commercial vehicle, the type specified in the preamble of claim 1 such that particularly high exhaust gas temperatures can be realized in a particularly simple manner, it is provided according to the invention that to increase the temperature of the exhaust gas Blocking element, by means of which the flow cross section of the first exhaust gas flow and a flow cross section of the return line are adjustable, in a flow cross section of the return line at least partially releasing and the flow cross section of the first exhaust gas flow at least partially obstructing open position is moved. The blocking element is moved for example from a closed position to an open position, wherein in the closed position, the return line is at least partially blocked by the blocking element. In other words, in the closed position, at least a portion of a cross-section of the return line through which the exhaust gas can flow is blocked by the blocking element.

In addition, in the closed position, the portion of the flow cross section of the first exhaust gas flow is released. For example, the return line is completely blocked in the closed position, so that no exhaust gas can flow into the return line or completely flow through it and can be returned to the intake tract.

In the open position in which the blocking element is moved, the return line is further released relative to the closed position. This means that the subregion of the flow cross section of the return line is released in the open position. Thus, in comparison to the closed position, a larger amount of exhaust gas or even exhaust gas can be diverted from the first exhaust gas flow, wherein this branched exhaust gas can flow completely through the return line, so that it can be returned to the intake.

In addition, the portion of the flow cross section of the first exhaust gas flow is blocked by the blocking element in the open position. In other words, the first exhaust gas flow is at least partially obstructed by means of the blocking element in the open position and more obstructed in comparison to the closed position.

In an advantageous embodiment of the invention, the first exhaust gas flow is completely fluidly blocked by moving the locking element in the open position. As a result, the power of the exhaust gas turbocharger with respect to the closed position can be reduced particularly clearly, so that the previously described effect of increasing the fuel fraction with respect to the air fraction occurs particularly strongly. As a result, a particularly significant increase in the exhaust gas temperature can be effected.

A further embodiment is characterized in that the exhaust gas supplied to the first exhaust gas flow is completely returned to the intake system. As a result, the intake tract, in particular the charge air housing, can be heated particularly strongly, as a result of which a particularly great increase in the exhaust gas temperature can be achieved.

As further particularly advantageous, it has been shown that the exhaust gas is supplied via at least one of the exhaust gas flows to an exhaust gas aftertreatment device arranged downstream of the turbine. If the first exhaust gas flow is blocked completely fluidically, then at least part of the exhaust gas flowing through the second exhaust gas flow is fed to the exhaust gas aftertreatment device. The exhaust gas flowing through the exhaust gas aftertreatment device can heat the exhaust gas aftertreatment device particularly strongly and in a particularly short time since, as described above, it has a particularly high temperature. In this way, for example, during a cold start of the internal combustion engine, a so-called warm-up phase, during which the exhaust gas aftertreatment device is warmed up to its operating temperature, be kept particularly short, so that a particularly low-emission operation of the internal combustion engine can be realized in total.

In a particularly advantageous embodiment of the invention, the flow cross-section of the return line, through which exhaust gas can flow, is maximally released in the open position of the blocking element relative to its adjustment range in which the adjusting element is adjustable. This means that the blocking element can be adjusted in its adjustment range, wherein the adjustment range comprises at least the closed position and the open position. In this embodiment, it is provided that the adjustment does not include a position of the blocking element, in which the flow cross section of the return line can be further released or stronger than in the open position. In other words, the adjusting element can not be moved into a position in which the flow cross section of the return line is further released or stronger than in the open position. By adjusting the blocking element can thus be recycled from the first exhaust gas flow, a particularly high amount of exhaust gas, so that there is a particularly strong and rapid increase in the exhaust gas temperature due to the above relationship.

As further particularly advantageous, it has been shown that the method is carried out in a fired partial load operation of the internal combustion engine. This is particularly advantageous, since efficient combustion can be shown, in particular in part-load operation even with very high exhaust gas recirculation rates and thus in a part-load operation, in which the exhaust gas flows are usually traversed with only a small exhaust gas mass flow, a particularly high exhaust gas temperature and consequently an effective and efficient operation of the exhaust aftertreatment device can be achieved. The partial load operation is, for example, a low to medium load range of the internal combustion engine, in particular the method is carried out in a load range of up to and including 800 newton meters, including 400 Newton meters.

In a further embodiment, it is provided according to the invention that the same amount of fuel is introduced into the combustion chambers during part-load operation. In other words, a symmetrical introduction or injection of preferably liquid fuel is provided in the combustion chambers formed, for example, as cylinders. To realize the high exhaust gas temperatures, no asymmetric introduction of fuel into the combustion chambers is required in the process. Rather, a symmetrical introduction of fuel is carried out in the combustion chambers, so that the method is particularly simple and inexpensive to carry out. Furthermore, to achieve the high exhaust gas temperature, the blocking element is sufficient as an actuator or actuator. Additional actuators such as a variable Turbine geometry of the turbine and / or a throttle valve and / or a wastegate of the turbine and a control of these actuators are not provided and not required to increase the exhaust gas temperature.

Another embodiment is characterized in that the method is carried out in a coasting operation of the internal combustion engine. By adjusting the locking element in the open position of the fresh air flow rate can be kept low by the internal combustion engine in overrun, so that as a result, the cooling of the internal combustion engine or its components can be kept low. Thus, a relatively high exhaust-gas temperature can be achieved, in particular during overrun, and a cooling down of the exhaust-gas aftertreatment device can consequently be reduced or avoided, so that an effective and efficient operation of the exhaust-gas aftertreatment device in a fired operation following the overrun operation can be realized without additional warm-up phase of the exhaust aftertreatment device.

In a further advantageous embodiment of the invention, a tempering device is arranged in the return line, by means of which the recirculated exhaust gas flowing through the return line is heated in the overrun mode. By heating the exhaust gas, the intake tract and / or gas flowing through it can be heated particularly strongly, which likewise achieves a positive effect on increasing the exhaust gas temperature.

To realize a particularly efficient and effective heating of the exhaust gas flowing through the return line in overrun operation, the tempering device comprises at least one heat exchanger, by means of which the exhaust gas, which is cooler in contrast to the part-load operation, is heated in the overrun mode. This heat exchanger is, for example, a cooler, which is also commonly referred to as an exhaust gas recirculation cooler. The exhaust gas recirculation cooler (heat exchanger) can be traversed by the recirculating exhaust gas as the first medium and by a second medium different from the exhaust gas to be recirculated. The second medium is, for example, a liquid, in particular a cooling liquid for cooling the internal combustion engine. as a result of a heat transfer from the second medium to the first medium (exhaust gas to be recirculated), the recirculated exhaust gas is heated in the overrun mode before it flows into the intake tract. When it flows into the intake tract and when it flows through the intake tract, the recirculated exhaust gas in the overrun operation to a particularly high temperature, resulting in a particularly high temperature of a gas, in particular the air results, or flows into the combustion chambers. As a result, a particularly high exhaust gas temperature can be achieved. In a fired operation of the internal combustion engine, for example, in the aforementioned part-load operation, however, the exhaust gas recirculation cooler is used for cooling the exhaust gas recirculated via the return line.

In the method according to the invention is a simple, but highly efficient and effective measure to significantly increase the exhaust gas temperature compared to the closed position of the blocking element by the blocking element is moved from the closed position to the open position. By compared to the closed position stronger release of the return line a particularly large amount of exhaust gas is diverted from the first exhaust gas flow and returned via the return line in the intake, so that the turbine and the exhaust gas turbocharger as a whole in comparison to the closed position energy is withdrawn. As a result, by moving the blocking element into the open position, the fresh air mass that is supplied to the internal combustion engine is reduced. As a result, the proportion of fuel is increased in comparison to the air content of a fuel-air mixture in the respective combustion chambers and the exhaust gas temperature rises. In addition, since a particularly large amount of exhaust gas is recirculated, the recirculated exhaust gas causes an increase in the temperature in the intake tract, in particular in a charge air housing, by means of which by the exhaust gas turbocharger compressed air is divided or supplied to the combustion chambers. As a result, an additional increase in the exhaust gas temperature can be achieved. In addition, a reduction of the fresh air flow rate can be effected by the internal combustion engine, especially in its overrun mode, so that a cooling of the internal combustion engine or its components can be kept low.

In other words, to realize the high exhaust gas temperature, it is intended to change an operating mode of the internal combustion engine and accordingly to set an operating mode in which the blocking element is moved to the open position. In this operating mode, the blocking element is opened, at least in wide partial load ranges and / or in overrun mode, in order to significantly increase the exhaust gas temperature compared to the closed position.

The invention also includes an internal combustion engine for a motor vehicle, in particular a commercial vehicle, wherein the internal combustion engine is designed to carry out the method according to the invention. The advantages and embodiments of the invention Process are to be regarded as advantages and refinements of the internal combustion engine according to the invention and vice versa.

Further advantages, features and details of the invention will become apparent from the following description of preferred embodiments and from the drawing. The features and feature combinations mentioned above in the description as well as the features and feature combinations mentioned below in the description of the figures and / or in the figures alone can be used not only in the respectively specified combination but also in other combinations or in isolation, without the scope of To leave invention.

The drawing shows in:

1 a schematic view of an internal combustion engine for a motor vehicle, in particular a commercial vehicle, which is operated according to a method in which the combustion chambers of the internal combustion engine, the same amount of fuel is introduced, wherein for increasing the exhaust gas temperature, a blocking element is moved from a closed position to an open position;

2 a schematic sectional view of a first embodiment of an exhaust tract of the internal combustion engine according to FIG 1 ; and

3 a fragmentary sectional view of a second embodiment of the exhaust tract.

In the figures, the same or functionally identical elements are provided with the same reference numerals.

1 shows a schematic representation of an internal combustion engine 10 for a motor vehicle, in particular a commercial vehicle. The internal combustion engine 10 is a drive unit and serves to drive the motor vehicle. The internal combustion engine 10 is designed as a reciprocating internal combustion engine and includes a first cylinder group 12 with present three first combustion chambers in the form of cylinders 14 . 16 and 18 , Furthermore, the internal combustion engine comprises 10 a second cylinder group 20 with present three second combustion chambers in the form of cylinders 22 . 24 and 26 ,

As part of a fired operation of the internal combustion engine 10 gets into the cylinder 14 . 16 . 18 . 22 . 24 . 26 Introduced air and injected liquid fuel. The liquid fuel is preferably introduced directly into the cylinders by means of a respective injector 14 . 16 . 18 . 22 . 24 . 26 injected. By introducing air and fuel into the cylinders 14 . 16 . 18 . 22 . 24 . 26 is formed in these a fuel-air mixture. The respective fuel-air mixture is ignited and thereby burned. This combustion results in exhaust gas.

As part of a push operation of the internal combustion engine 10 gets into the cylinder 14 . 16 . 18 . 22 . 24 . 26 Air introduced and no fuel injected. The resulting exhaust gas has a significantly lower temperature than in the fired operation of the internal combustion engine 10 ,

Out 1 It can be seen that in the course of a method for operating the internal combustion engine 10 the exhaust gas from the first cylinders 14 . 16 . 18 a first exhaust gas flow 28 is supplied. The exhaust gas from the second cylinders 22 . 25 . 26 one is at least partially from the first exhaust flow 28 fluidly separated, second exhaust gas flow 30 fed.

The exhaust fumes 28 . 30 are each fluidic with a turbine 32 one with the whole 34 designated exhaust gas turbocharger of the internal combustion engine 10 fluidly connected. This allows the respective, the exhaust fumes 28 . 30 flowing exhaust gas of the turbine 32 be supplied. Out 1 is recognizable that the turbine 32 with a first turbine flood 36 the turbine 32 is fluidically connected. The exhaust gas flow 30 is with a second turbine flood 38 the turbine 32 fluidly connected. The turbine 32 is designed as an asymmetric turbine, the turbine floods 36 . 38 are formed asymmetrically relative to each other. In the present case, this is the first turbine flood 36 around a so-called small turbine tide, which faces the second turbine tide 38 is smaller or has a smaller flow cross-section through which the exhaust gas can flow.

About the turbine floods 36 . 38 that will come from the exhaust fumes 28 . 30 into the turbine floods 36 . 38 inflowing and the turbine floods 36 . 38 flowing exhaust gas to a in 1 unrecognizable turbine wheel of the turbine 32 directed so that the turbine wheel from which the turbine floods 36 . 38 flowing exhaust gas is driven. The turbine 32 is in one with the whole 40 designated exhaust tract of the internal combustion engine 10 arranged. The turbine 32 may alternatively be designed as a symmetrical turbine, in which the turbine floods 36 . 38 have at least substantially the same flow cross-sections.

In the exhaust tract 40 is downstream of the turbine 32 an exhaust aftertreatment device 42 arranged. The exhaust aftertreatment device 42 is used to treat the exhaust gas before it flows into the environment.

The turbocharger 34 also includes one in an intake tract 44 arranged compressor 46 which is a in 1 unrecognizable compressor wheel comprises. The compressor wheel and the turbine wheel are with a shaft 49 the exhaust gas turbocharger 34 rotatably connected, so that the compressor wheel can be driven by the turbine. By means of the compressor wheel, air is compressed, that of the compressor 46 in a charge air housing 48 the intake tract 44 flows. By means of the charge air housing 48 which is commonly referred to as a charge air manifold, the compressed air is applied to the cylinders 14 . 16 . 18 . 22 . 24 . 26 divided and flows from the charge air housing 48 in the cylinders 14 . 16 . 18 . 22 . 24 . 26 ,

The internal combustion engine 10 also includes an exhaust gas recirculation device 50 with an exhaust gas recirculation line 52 , which is also referred to as "return line". The exhaust gas recirculation line 52 is at a sampling point E fluidly with the first exhaust gas flow 28 connected. Furthermore, the exhaust gas recirculation line 52 at a supply Z fluidly with the intake 44 connected. By means of the exhaust gas recirculation line 52 can exhaust gas at the extraction point E from the first exhaust gas flow 28 be diverted. The branched off exhaust gas flows through the exhaust gas recirculation line 52 and can via the exhaust gas recirculation line 52 at the feed Z in the intake 44 be initiated. This causes the recirculated exhaust gas to enter the cylinders 14 . 16 . 18 . 22 . 24 . 26 supplied to incoming air, leaving in the cylinder 14 . 16 . 18 . 22 . 24 . 26 not only air, but a mixture of the air and the recirculated exhaust gas flows. This allows a particularly low-emission operation of the internal combustion engine 10 will be realized.

The exhaust gas recirculation device 50 also includes a tempering device 54 , which in the exhaust gas recirculation line 52 is arranged. The tempering device 54 is used for temperature control of the recirculating and the exhaust gas recirculation line 52 flowing exhaust gas. For this purpose, the tempering device comprises 54 a heat exchanger in the form of an exhaust gas recirculation cooler 56 , which is traversed by the recirculating exhaust gas as the first medium. In addition, the exhaust gas recirculation cooler 56 permeated by a second medium. The second medium is a cooling fluid, by means of which the internal combustion engine 10 , in particular their crankcase and / or their cylinder head, are cooled. As a result of a heat transfer from the exhaust gas recirculation cooler 56 flowing exhaust gas to the cooling liquid or vice versa, the recirculating exhaust gas can be tempered. In a fired operation, there is a heat transfer from the exhaust gas to the coolant. In a pushing operation, heat is transferred from the cooling liquid to the exhaust gas.

In the exhaust tract 40 is also one of the first exhaust fumes 28 and the exhaust gas recirculation line 52 associated, that is, the first exhaust gas flow 28 and the exhaust gas recirculation line 52 common blocking element in the form of a flap 58 arranged. The flap 58 is also referred to as exhaust gas recirculation flap (EGR flap), as by means of the flap 58 - As will be explained below - a flow cross-section of the exhaust gas recirculation line 52 and thus, an amount of the exhaust gas to be recirculated can be adjusted. In addition, by means of the flap 58 - As will be explained below - a flow cross-section of the first exhaust gas flow 28 be set.

Out 1 is also a control device in the form of a control unit 60 for controlling and / or controlling the internal combustion engine 10 recognizable. The control unit 60 is also called a "control unit". in particular, by means of the control device 60 the introduction of the fuel and the air, that is the fuel-air mixture, adjusted regulated. In addition, by means of the control unit 60 the flap 58 Regulated or controlled with regard to their position. The flap 58 is movable in an adjustment and can be moved into at least one open position and at least one closed position.

To now the exhaust aftertreatment device 42 for example, during a cold start of the internal combustion engine 10 particularly fast, that is to heat in a particularly short time and bring to operating temperature, a particularly high temperature of the exhaust aftertreatment device 42 flowing exhaust gas causes by the flap 58 from one the exhaust gas recirculation line 52 fluidly at least partially obstructing and at least a portion of a flow cross-section through which the exhaust gas can flow through the first exhaust gas flow 28 releasing closed position in an exhaust gas recirculation line 52 towards the closed position further releasing and the portion of the flow cross section of the first exhaust gas flow 28 fluidly obstructing open position is moved. In addition, in the cylinder 14 . 16 . 18 . 22 . 24 . 26 the same amount of fuel introduced, that is injected. In other words, a symmetrical injection into the cylinder 14 . 16 . 18 . 22 . 24 . 26 carried out.

2 shows the exhaust tract 40 according to a first embodiment. The exhaust fumes 28 . 30 are doing of an exhaust piping 62 formed and by means of an intermediate wall 64 the exhaust piping 62 fluidly separated from each other. directional arrows 66 illustrate the flow of exhaust gas through the exhaust gas flows 28 . 30 ,

Out 2 is recognizable that the flap 58 around a pivot axis 68 is pivotable. The flap 58 is movable in several positions, of which in 2 four positions 1 . 2 . 3 . 4 are shown. The aforementioned closed position is the position 1 , wherein the aforementioned open position, the position 2 is. With the reference numerals 3 and 4 are more positions of the flap 58 referred to in the flap 58 can be moved. The pivotability of the flap 58 is in 2 by a directional arrow 70 illustrated.

The position 1 is a first closed position, in which a flow of exhaust gas from the first exhaust gas flow 28 into the exhaust gas recirculation line 52 is prevented. In other words, the exhaust gas recirculation line 52 in the position 1 fluidly obstructed, so that they can not be traversed by exhaust gas. In addition, there is a connection opening 72 provided over which the exhaust fumes 28 . 30 fluidly connected to each other. The connection opening 72 is in the middle wall 64 provided and in the first closed position (position 1 ) Approved. By means of the flap 58 are thus the connection opening 72 between the exhaust fumes 28 . 30 and the exhaust gas recirculation line 52 and the first exhaust tide 28 fluidic lockable and fluidic releasable. The connection opening 72 is as a passage opening 74 the partition wall 64 formed, wherein the passage opening 74 from walls 76 the partition wall 64 is limited.

In addition, the first exhaust tide 28 by means of the flap 58 in the first closed position (position 1 ) downstream of the connection opening 72 fluidly blocked. This means that the first exhaust tide 28 downstream of the connection opening 72 no more exhaust gas flows through it. This is the first exhaust flow 28 upstream of the connection opening 72 flowing exhaust gas thus flows in the first closed position through the shared connection opening 72 through into the second exhaust gas flow 30 so that all the exhaust gas from all cylinders 14 . 16 . 18 . 22 . 24 . 26 the second exhaust gas flow 30 downstream of the connection opening 72 flows through. This overflow of the exhaust gas from the first exhaust gas flow 28 in the second exhaust gas flow 30 is in 2 by a directional arrow 78 illustrated.

Because in the position 1 the exhaust gas recirculation line 52 and the first exhaust tide 28 are closed and the connection opening 72 from the first exhaust 28 to the second exhaust gas flow 30 is open, it comes to a heavy charge of the internal combustion engine 10 through the exhaust gas turbocharger 34 , which is associated with a high engine braking performance. In this engine braking mode, no fuel gets into the cylinders 14 . 16 . 18 . 22 . 24 . 26 injected, causing the internal combustion engine 10 is operated as a turbomachine. By merging the exhaust gas of all cylinders 14 . 16 . 18 . 22 . 24 . 26 in the second exhaust gas flow 30 can through a then optimal flow to the turbine 32 a particularly effective charging of the internal combustion engine 10 be achieved in engine braking. Furthermore, the position 1 for a load jump in the fired operation of the internal combustion engine 10 to prefer, there with a corresponding load request to the internal combustion engine 10 the entire exhaust exclusively via the second exhaust gas flow 30 on the turbine 32 the exhaust gas turbocharger 34 can act, so that a correspondingly increased boost pressure by means of the compressor 46 can be realized. As a result, the internal combustion engine 10 provide a higher torque very quickly.

The number of parts of the exhaust tract 40 can be kept very low, as the one flap 58 both for fluidic obstruction of the first exhaust gas flow 28 downstream of the connection opening 72 as well as for the fluidic obstruction of the exhaust gas recirculation line 52 is used. For this the flap protrudes 58 in her position 1 with a first subarea 80 into the first exhaust gas flow 28 and with an adjoining, second subarea 82 into the exhaust gas recirculation line 52 into it. The first subarea is used here 80 for the fluidic obstruction of the first exhaust gas flow 28 downstream of the connection opening 72 while the second subarea 82 for fluidic blocking of the exhaust gas recirculation line 52 is used. The two subareas 80 . 82 the flap 58 each pivot about the pivot axis 68 ,

At the position 2 it is a first open position of the flap 58 , wherein this first open position is related to 1 called open position. In the position 2 that is, in the first open position, is the connection opening 72 fluidly obstructed, so that they can not be traversed by exhaust gas. Furthermore, in the position 2 the first exhaust gas flow 28 downstream of the removal point E fluidly blocked, so that they can not be flowed through by exhaust gas then. This means that the entire, the first exhaust tide 28 Exhaust gas flowing from the first exhaust gas flow upstream of the removal point E. 28 branched off and the exhaust gas recirculation line 52 is supplied. As a result, a maximum adjustable exhaust gas recirculation rate (EGR rate) is set. In the first open position (position 2 ), the exhaust gas from the three cylinders 14 . 16 . 18 completely via the exhaust gas recirculation line 52 in the intake tract 44 recycled.

At the position 3 it is a second open position or intermediate position of the flap 58 , for example, in a main driving range of the internal combustion engine 10 is set. In the second open position (position 3 ) are both the Exhaust gas recirculation line 52 as well as the first flood of the exhaust 28 as well as the connection opening 72 released and therefore flowed through by exhaust gas. By a variation of the intermediate position, the exhaust gas of the internal combustion engine 10 accordingly in the exhaust gas recirculation line 52 , the first exhaust 28 and the connection opening 72 be split.

At the position 4 the flap 58 it is a second closed position, in which the exhaust gas recirculation line 52 is also fluidly locked. The connection opening 72 is however released. In the second closed position (position 4 ) is also the first exhaust gas flow 28 Approved. This means that in the second closed position (position 4 ) Both exhaust gas flows 28 . 30 can be flowed through by respective exhaust gas and in particular for a full load operation of the internal combustion engine 10 suitable is.

As in 2 is recognizable, are the exhaust gas flows 28 . 30 asymmetrically formed. In this case, the first exhaust gas flow 28 a smaller flow cross-section through which the exhaust gas can flow than the second exhaust gas flow 30 , Since the exhaust gas recirculation line 52 from the first exhaust 28 branches off, becomes the first exhaust gas flow 28 also referred to as EGR flood (exhaust gas recirculation). The first exhaust tide 28 thus serves in particular to provide exhaust gas at a high pressure for exhaust gas recirculation. The flow cross section of the first exhaust gas flow 28 is particularly designed for a pressure of the exhaust gas, which exceeds a pressure on the inlet side. The pressure of the combustion air on the intake side of the internal combustion engine 10 is through the compressor 46 the exhaust gas turbocharger 34 lifted and must be for exhaust gas recirculation from the pressure of the exhaust gas recirculation line 52 Incoming exhaust gas can be exceeded.

Alternatively, it is conceivable, the two exhaust gas flows 28 . 30 to perform symmetrically with respect to their respective flow cross sections. By a corresponding variation, in particular the second open position (position 3 ), the flow cross-section of the first exhaust gas flow 28 only be reduced so far that a pressure of the exhaust gas in the first exhaust gas flow 28 and in particular in the exhaust gas recirculation line 52 exceeds a pressure on the inlet side. Advantageously, due to the larger flow cross section given by the symmetry, the first exhaust gas flow decreases 28 the pressure of the exhaust gas in the first exhaust gas flow 28 so that the internal combustion engine 10 with the first flood of the exhaust 28 associated cylinders 14 . 16 . 18 less power to exhaust the exhaust gas from the cylinders 14 . 16 . 18 in the exhaust side, which increases the efficiency of the internal combustion engine 10 increases and at the same time the consumption and exhaust emissions decrease.

Out 2 is recognizable that the flap 58 both the exhaust gas recirculation line 52 as well as the first flood of the exhaust 28 as well as the connection opening 72 is assigned and used for fluidic locking and releasing this. Thus, the number of parts and the complexity of the exhaust tract 40 be kept particularly low.

To realize a low-emission operation of the internal combustion engine 10 and for the realization of high engine braking performance, an equal number of cylinders can each exhaust gas flows 28 . 30 be assigned. Of course, however, an uneven distribution of the cylinder to the exhaust gas flows 28 . 30 conceivable. To flow losses in the exhaust tract 40 In addition, to keep particularly low, can be advantageously provided that the flap 58 in the main driving range at least substantially parallel to the flow direction of the exhaust gas through the exhaust piping 62 or by the first exhaust gas flow 28 runs.

Is the flap 58 in the position 2 (First open position), whereby particularly high exhaust gas temperatures are effected, so the exhaust gas aftertreatment device 42 Exhaust gas of the internal combustion engine 10 over the second exhaust gas flow 30 fed. Since that is the second exhaust gas flow 30 flowing exhaust gas has a particularly high temperature, the exhaust aftertreatment device 42 be heated up very quickly.

At the position 2 (first open position) is a so-called maximum open position or a full open position of the flap 58 , In the position 2 namely, is the flow cross section of the exhaust gas recirculation line through which exhaust gas can flow 52 based on the adjustment of the flap 58 maximally released. This means that the adjustment range of the flap 58 does not include a position in which the means of the flap 58 adjustable flow cross-section of the exhaust gas recirculation line 52 stronger or larger or larger area could be released as in the position 2 ,

A particularly high exhaust gas temperature can be realized if the exhaust gas recirculation cooler 56 in the operating mode of the internal combustion engine 10 in which the flap to increase the exhaust gas temperature 58 in the position 2 is moved, for heating the exhaust gas recirculation line 52 flowing exhaust gas is used in overrun. In other words, it is provided in the operating mode that the exhaust gas recirculation line 52 flowing exhaust gas by means of the exhaust gas recirculation cooler 56 is heated. For example, there is a heat transfer from the cooling liquid via the exhaust gas recirculation cooler 56 to the recirculating, the exhaust gas recirculation cooler 56 flowing exhaust gas instead. By heating the recirculated exhaust gas, for example, the charge air housing 48 be heated, which makes the cylinder 14 . 16 . 18 . 22 . 24 . 26 incoming gas is heated. This has a beneficial effect on increasing the exhaust gas temperature during overrun.

3 shows a second embodiment of the exhaust tract 40 , In 4 is by a directional arrow 84 the flow of exhaust gas through the exhaust gas recirculation line 52 illustrated. In 3 are three positions 5 . 6 and 7 the flap 58 shown. The position 5 corresponds in functional terms to the position 2 because the flow cross-section of the exhaust gas recirculation line 52 in the position 5 maximum is released. Furthermore, the first exhaust gas flow 28 in the position 5 partially blocked. In the position 5 is however the first exhaust gas flow 28 not completely fluidly blocked. This means that in the position 5 still exhaust through the exhaust gas 28 can flow through.

In other words, in the position 5 a partial region of the flow cross section of the first exhaust gas flow 28 through the fold 58 fluidly obstructed, while an adjoining, second portion of the flow cross-section of the first exhaust gas flow 28 is released.

The position 7 corresponds in functional terms to the position 4 because in the position 7 the flow cross-section of the exhaust gas recirculation line 52 fluidly obstructed and the portion of the first exhaust gas flow 28 who is in the position 5 is fluidically locked fluidly released. The position 6 corresponds in functional view of the position 3 , To increase the exhaust gas temperature is the flap 58 for example, from the position 7 in the position 5 moved so that the exhaust gas recirculation line 52 released and the first exhaust tide 28 is at least partially blocked fluidly.

QUOTES INCLUDE IN THE DESCRIPTION

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Cited patent literature

• DE 102008064264 A1 [0002]

Claims (11)

Method for operating an internal combustion engine ( 10 ) of a motor vehicle, wherein exhaust gas from at least a first combustion chamber ( 14 ) of the internal combustion engine ( 10 ) one with a turbine ( 32 ) of an exhaust gas turbocharger ( 34 ) fluidly connected, first exhaust gas flow ( 28 ) and exhaust gas from at least one second combustion chamber ( 22 ) of the internal combustion engine ( 10 ) one with the turbine ( 32 ) of the exhaust gas turbocharger ( 34 ) fluidly connected, second exhaust gas flow ( 30 ), in which exhaust gas from the first exhaust gas flow ( 28 ) and via a return line ( 52 ) into an intake tract ( 44 ) of the internal combustion engine ( 10 ) is recirculated and in which a flow cross-section of the first exhaust gas flow through the exhaust gas ( 28 ) is at least partially fluidly blocked, characterized in that for increasing the temperature of the exhaust gas, a blocking element ( 58 ), by means of which the flow cross-section of the first exhaust gas flow ( 28 ) and a flow cross-section of the return line ( 52 ) are adjustable, in a flow cross-section of the return line ( 52 ) at least partially releasing and the flow cross section of the first exhaust gas flow ( 28 ) at least partially obstructing open position ( 2 ) is moved. Method according to claim 1, characterized in that the first exhaust gas flow ( 28 ) by moving the locking element in the open position ( 2 ) is completely fluidly blocked. Method according to claim 2, characterized in that that of the first exhaust gas flow ( 28 ) supplied exhaust gas completely into the intake tract ( 44 ) is returned. Method according to one of the preceding claims, characterized in that exhaust gas over at least one of the exhaust gas flows ( 28 . 30 ) one in particular downstream of the turbine ( 32 ) arranged exhaust gas aftertreatment device ( 42 ) is supplied. Method according to one of the preceding claims, characterized in that the flow cross section of the return line ( 52 ) in the open position ( 2 ) of the blocking element ( 58 ) based on the adjustment range in which the blocking element ( 58 ) is adjustable, maximum is released. Method according to one of the preceding claims, characterized in that the method in a partial load operation of the internal combustion engine ( 10 ) is carried out. Method according to claim 6, characterized in that into the combustion chambers ( 14 . 22 ) the same amount of fuel is introduced. Method according to one of claims 1 to 5, characterized in that the method in a coasting operation of the internal combustion engine ( 10 ) is carried out. Method according to claim 8, characterized in that in the return line ( 52 ) a tempering device ( 54 ) is arranged, by means of which the recirculating, the return line ( 52 ) flowing exhaust gas is heated. Method according to claim 9, characterized in that the tempering device ( 54 ) at least one exhaust gas recirculation cooler ( 56 ), by means of which the exhaust gas is heated. Internal combustion engine ( 10 ) for a motor vehicle, which is designed to carry out a method according to one of the preceding claims.

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