DE102013020403A1 - Method for operating an internal combustion engine, in particular a motor vehicle - Google Patents

Abstract

The invention relates to a method for operating an internal combustion engine which has an exhaust gas tract (40) with at least one exhaust gas flow passable by exhaust gas, with at least one turbine (32) of an exhaust gas turbocharger (34) fluidically connected to the exhaust gas flow (28) with the exhaust gas flow (28) fluidly connected exhaust gas recirculation line (52) for branching off exhaust gas from the exhaust gas flow (28) and with a relative to the exhaust gas recirculation line and relative to the exhaust gas flow (28) movable blocking element (58), by means of both a flow-through of exhaust flow cross-section Exhaust gas recirculation line (52) and an exhaust gas flow-through flow cross-section of the exhaust gas flow (28) is adjusted, wherein a rotational speed of the exhaust gas turbocharger (34) by moving the locking element (58) is adjusted.

Description

The invention relates to a method for operating an internal combustion engine, in particular a motor vehicle, according to the preamble of patent claims 1 and 5.

Such a method for operating an internal combustion engine, in particular a motor vehicle, is the DE 10 2008 064 264 A1 to be known as known. The internal combustion engine comprises an exhaust gas tract, which has at least one exhaust gas flow through exhaust gas and at least one turbine of an exhaust gas turbocharger. The turbine is fluidly connected to the exhaust gas flow, so that exhaust gas flowing through the exhaust gas flow of the internal combustion engine is guided to the turbine.

The exhaust gas tract further has an exhaust gas recirculation line, which is fluidically connected to the exhaust gas flow, for branching off exhaust gas from the exhaust gas flow. By means of the exhaust gas recirculation line, the exhaust gas branched off from the exhaust gas flow is returned to an intake tract of the internal combustion engine. The intake tract can be traversed by air, which is guided by means of the intake tract into at least one combustion chamber, in particular a cylinder, of the internal combustion engine.

In addition, the exhaust tract to a blocking element which is movable relative to the exhaust gas recirculation line and relative to the exhaust gas flow. In the context of the method, by means of the blocking element, both a flow cross-section of the exhaust gas recirculation line through which exhaust gas can flow and the exhaust gas flow cross-section through which the exhaust gas can flow are set. In other words, one and the same blocking element serves for adjusting both the flow cross section of the exhaust gas flow and for adjusting the flow cross section of the exhaust gas recirculation line. This makes it possible to adjust by means of the blocking element, a mass or amount of exhaust gas flowing through the exhaust gas recirculation line and a quantity or mass of the exhaust gas flowing through the exhaust gas flow.

Object of the present invention is to develop a method for operating an internal combustion engine of the type mentioned in such a way that a particularly simple, weight and cost effective and reliable operation of the internal combustion engine can be realized.

This object is achieved by a method having the features of patent claim 1 and by a method having the features of patent claim 5. Advantageous embodiments with expedient and non-trivial developments of the invention are specified in the remaining claims.

To further develop a method specified in the preamble of claim 1 type such that a particularly simple, weight and cost effective and reliable operation of the internal combustion engine can be realized, it is inventively provided that a speed of the exhaust gas turbocharger by moving the locking element, that is by Setting this is set. It is provided that the blocking element is set in dependence on the rotational speed of the exhaust gas turbocharger, that is, in response to at least one, the speed of the exhaust gas turbocharger characterizing value.

The present invention is based on the finding that the speed of the exhaust gas turbocharger depends on the position of the blocking element and can therefore be adjusted by adjusting, that is moving the blocking element. For example, it is provided in the method according to the invention to determine at least one value characterizing the rotational speed of the exhaust gas turbocharger. For this purpose, the speed of the exhaust gas turbocharger is detected, for example, by means of a speed sensor. Alternatively or additionally, it is possible to calculate the rotational speed of the exhaust gas turbocharger on the basis of at least one model.

This value characterizing the rotational speed of the exhaust-gas turbocharger is used as the actual value and compared with at least one predefinable nominal value. If the actual value deviates from the desired value and this deviation is, for example, above a predefinable threshold value, then the blocking element is adjusted by means of a control unit for regulating or controlling the internal combustion engine such that the actual value at least substantially corresponds to the desired value ,

By using the locking element for adjusting the rotational speed of the exhaust gas turbocharger and by adjusting the locking element as a function of the rotational speed of the exhaust gas turbocharger further actuators such as a wastegate of the turbine and / or a variable geometry of the turbine for adjusting the rotational speed of the exhaust gas turbocharger are not required and not intended. Thereby, the speed of the exhaust gas turbocharger can be set in a simple, cost and weight-favorable manner. In particular, it is thus possible to set the actual speed or the actual value to a predefinable setpoint speed or a predefinable setpoint value and to enable a particularly functionally reliable operation of the internal combustion engine.

The speed of the exhaust gas turbocharger is adjustable as needed in a particularly large adjustment, since the blocking element due to the adjustability of both the flow cross section of the exhaust gas flow and the flow cross section of the exhaust gas recirculation line has a large adjustment and thus a plurality of different positions is adjustable, which different speeds of the exhaust gas turbocharger cause.

In a particularly advantageous embodiment of the invention, the rotational speed of the exhaust-gas turbocharger is kept below a predefinable threshold value by adjusting, that is to say by moving the blocking element. In other words, it is avoided by adjusting the blocking element that the rotational speed of the exhaust gas turbocharger exceeds the predefinable threshold value. This threshold is, for example, a so-called limiting speed which the exhaust-gas turbocharger should not exceed, since the exhaust-gas turbocharger could otherwise be damaged.

This embodiment is based on the finding that, for example, when driving uphill with increasing altitude above sea level, the ambient pressure drops. The consequence is that the speed of the exhaust gas turbocharger - especially in full load operation of the internal combustion engine - increases. Above this limit speed, damage to the exhaust gas turbocharger is possible, which is why this limit speed is monitored and maintained, that is, should not be exceeded. The compliance with this limit speed is possible in the process in a simple manner.

The setting of the blocking element as a function of the rotational speed of the exhaust gas turbocharger and the resulting adjustment of the rotational speed of the exhaust gas turbocharger takes place, for example, by means of a control unit for regulating or controlling the internal combustion engine. This control unit is supplied as an input variable, the actual speed of the exhaust gas turbocharger. The control unit receives the actual speed. The output signal output by the control unit is a signal by means of which the blocking element is adjusted, that is to say moved. The signal is transmitted to the blocking element and received by the blocking element, whereby the movement of the blocking element is effected in a position. As a result, the adjustment of the locking element takes place as a function of the rotational speed of the exhaust gas turbocharger. As a result, the turbine can be designed as a solid geometry turbine and can be dispensed with a wastegate.

The speed of the exhaust gas turbocharger can be adjusted by adjusting the locking element even when driving downhill and, for example, in an engine braking operation of the internal combustion engine. Even with such a downhill in engine braking operation, the limit speed is maintained to protect the exhaust gas turbocharger. When driving downhill in engine braking operation, for example, as the vehicle speed increases, the speed of the internal combustion engine and thus also the speed of the exhaust gas turbocharger increase. To avoid exceeding the limit speed, the blocking element is moved to a position in which adjusts a speed of the exhaust gas turbocharger, which is for example below the limit speed.

In an advantageous embodiment of the invention, in order to reduce the rotational speed of the exhaust gas turbocharger, the blocking element is moved from a first position into a second position, which fluidly obstructs the exhaust gas flow in relation to the first position. In other words, it is preferably provided that the blocking element is moved in such a way that the exhaust gas flow is increasingly blocked fluidically to maintain the limit speed via a suitable controller when reaching the limit speed or when a predefinable threshold value is exceeded. As a result, the exhaust gas turbocharger energy is withdrawn, so that its speed drops. The same can be done when driving uphill. This makes it possible, for example, to keep the actual speed of the exhaust gas turbocharger below the limit speed or set to the limit speed, that is regulate.

A further embodiment is characterized in that, in order to reduce the rotational speed of the exhaust-gas turbocharger, the blocking element is moved from a second position into a first position, which makes the exhaust-gas flow more fluidic than the second position. This makes it possible on the one hand to avoid exceeding the limit speed. On the other hand, it is possible to keep the speed of the exhaust gas turbocharger at a high level, so that, for example, the turbo lag can be avoided or at least kept low.

In order to develop an internal combustion engine specified in the preamble of claim 5 type such that a particularly simple, cost and weight-saving and reliable operation can be realized, it is inventively provided that at least one position of the blocking element in response to at least one operation of the internal combustion engine characterizing parameter is checked. As a result, a particularly simple, cost and weight-favorable on-board diagnostics (OBD) can be realized, in the context of which the position of the blocking element and thus the functionality of the blocking element can be checked.

To check an already available or detected parameters of the internal combustion engine is used, the value of which depends on the position of the blocking element. However, it is not intended and not necessary to directly detect the position of the blocking element by means of a sensor, for example a displacement sensor, but the check as to whether the blocking element assumes a desired, predetermined position takes place indirectly via the parameters characterizing the operation of the internal combustion engine ,

This aspect of the invention is based on the idea to use a parameter characterizing the operation of the internal combustion engine, which is detected anyway and which depends on the position of the blocking element, in order to check the function of the actuating element.

If the blocking element is actuated, for example, by a control unit for controlling or controlling the internal combustion engine, such a control is to take place, which is intended to bring about a movement of the blocking element from a first position into a different second position, and will change as a result of this activation of the blocking element detected, it can be concluded on the basis of the detection of the change that the activation of the blocking element was successful and the blocking element was actually moved from the first position to the second position.

However, if, on the basis of the detection of the parameter, it is determined that the parameter has not changed as a result of the activation of the blocking element or if there has been a change in the parameter which is different from an expected change, then it can be deduced from this non-occurring or unexpected change, that the activation of the blocking element was unsuccessful and that the blocking element and / or its activation is possibly defective.

In an advantageous embodiment of the invention, the parameter characterizes a gas, in particular a state of the gas, of the internal combustion engine. In other words, the parameter used is a parameter which characterizes a gas, in particular a state of the gas, of the internal combustion engine. The gas may be fresh air to be supplied to the internal combustion engine or exhaust gas flowing around the exhaust tract of the internal combustion engine. If the blocking element is functional, an adjustment of the blocking element to the gas, in particular to the state of the gas, has an effect. Usually, the state of the gas is already detected, so that it can be deduced on the basis of the detection of the state of the gas in a simple manner and without additional sensors on the functioning of the blocking element.

It has proved to be particularly advantageous if the parameter characterizes a pressure of the gas. Based on the monitoring of the pressure, in particular by monitoring a change in pressure, the gas can be particularly well deduced the functionality of the blocking element, since the adjustment of the blocking element usually causes a change in the pressure of the gas. If such a pressure change does not occur, it can be concluded that the blocking element is defective.

Another embodiment is characterized in that the parameter characterizes a temperature of the internal combustion engine. Also based on the monitoring of the temperature can be particularly meaningful conclusions on the functioning of the blocking element and thus the internal combustion engine.

Finally, it has proven to be particularly advantageous if the parameter characterizes a rotational speed of the exhaust gas turbocharger. As described above, the speed of the exhaust gas turbocharger depends on the position of the blocking element. If a change in the rotational speed of the exhaust-gas turbocharger remains in spite of a corresponding activation of the blocking element, or if the change in the rotational speed of the exhaust-gas turbocharger changes as a result of the activation, then a defect of the blocking element can be deduced with particular certainty.

The invention also includes an internal combustion engine, in particular for a motor vehicle, which is designed to carry out a method according to the invention. Advantageous embodiments of the method according to the invention are to be regarded as advantageous embodiments 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.

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 also 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 diverted become. 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 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 trained, the Through 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.

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 terms of before 1 said closed position, from the flap 58 in the position 2 (First open position) is moved, thereby increasing the exhaust gas temperature, it may be either to the first closed position (position 1 ) or the second closed position (position 4 ) act. 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. As a result, for example, an improved load step in the fired operation of the internal combustion engine 10 representable by the entire exhaust gas at a corresponding load request exclusively on the two exhaust gas flows 28 . 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.

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 With high engine braking powers, an equal number of cylinders can each exhaust the exhaust 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 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.

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.

This in 1 unrecognizable turbine wheel of the turbine 32 , this in 1 unrecognizable compressor wheel of the compressor 46 and the shaft rotatably connected to the turbine wheel and the compressor wheel 49 form a so-called rotor of the exhaust gas turbocharger 34 , During operation of the internal combustion engine 10 This rotor rotates about a rotation axis with different speeds.

As part of a method for operating the internal combustion engine 10 It is now envisaged that a speed of the exhaust gas turbocharger 34 that is a speed of the rotor by moving the flap 58 is set. This means that at least one value characterizing the rotational speed of the rotor is determined. The rotational speed of the rotor is detected, for example, by means of at least one rotational speed sensor. The speed sensor then sends the value characterizing the detected speed to the control unit (control unit 60 ) which receives the value characterizing the speed. Alternatively or additionally, it is possible by means of the control unit 60 Based on a simulation model, the speed of the rotor, that is, the speed of the exhaust gas turbocharger 34 , to calculate. The result of this calculation is then a value characterizing the rotational speed of the rotor. The value characterizing the speed is compared as an actual value with a predefinable desired value. The target value characterizes a limit speed of the rotor, which should not exceed the rotor, as it could otherwise be damaged.

If the actual value deviates from the desired value, or if such a deviation exceeds a predefinable threshold value, then the damper opens 58 from the controller 60 so controlled, that is set that the deviation of the actual value of the target value is at least lower and so that the speed of the rotor does not exceed the limit speed. This means the flap 58 by means of the control unit 60 is adjusted depending on the rotational speed of the rotor, wherein by adjusting the flap 58 the speed of the rotor is kept below the limit speed or at the limit speed.

To reduce the speed of the rotor, the flap 58 for example, from the position 6 in the position 5 moved, leaving the first exhaust 28 in the position 5 opposite the position 6 is more fluidic locked. With increasing obstruction of the first exhaust gas flow 28 becomes the exhaust gas turbocharger 34 or its turbine 32 increasingly deprived of energy, so that the speed of the rotor increasingly decreases. To the speed of the exhaust gas turbocharger 34 can increase again, the first exhaust gas flow 28 be released successively again.

In addition, in the internal combustion engine 10 In a particularly simple manner, a so-called on-board diagnostic feasible, in the context of which the function of the flap 58 can be checked. As already described, during operation of the internal combustion engine 10 the value characterizing the speed of the rotor anyway determined in order to protect the rotor from exceeding the limit speed.

The speed of the exhaust gas turbocharger 34 is the operation of the internal combustion engine 10 characterizing parameter. This parameter is monitored. Does it come as a result of the control of the flap 58 to an expected change of the monitored parameter, it can be concluded that the flap 58 assumes its desired position and thus is functional. However, it comes despite the control of the door 58 not to the expected change of the parameter, it can be concluded that the flap 58 not in its desired position and the control was unsuccessful. As a result, the operability of the flap 58 be checked without the position of the flap 58 to capture directly by means of a motion or position sensor.

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Cited patent literature

• DE 102008064264 A1 [0002]

Claims (10)

Method for operating an internal combustion engine, which has an exhaust gas tract ( 40 ) with at least one exhaust gas flow through the exhaust gas ( 28 ), with at least one with the exhaust gas flow ( 28 ) fluidly connected turbine ( 32 ) of an exhaust gas turbocharger ( 34 ), with one with the exhaust gas flow ( 28 ) fluidly connected exhaust gas recirculation line ( 52 ) for branching off exhaust gas from the exhaust gas flow ( 28 ) and with a relative to the exhaust gas recirculation line and relative to the exhaust gas flow ( 28 ) movable blocking element ( 58 ), by means of which both a flow cross section of the exhaust gas recirculation line through which exhaust gas can flow ( 52 ) as well as a flow cross-section through which the exhaust gas can flow ( 28 ) is set, characterized in that a rotational speed of the exhaust gas turbocharger ( 34 ) by moving the blocking element ( 58 ) is set. Method according to claim 1, characterized in that by adjusting the blocking element ( 58 ) the speed of the exhaust gas turbocharger ( 34 ) is kept below a predefinable threshold. Method according to one of claims 1 or 2, characterized in that for reducing the rotational speed of the exhaust gas turbocharger ( 34 ) the blocking element ( 58 ) from a first position ( 6 ) in one the exhaust gas flow ( 28 ) compared to the first position ( 6 ) more fluidly obstructing second position ( 5 ) is moved. Method according to one of the preceding claims 1 or 2, characterized in that for reducing the rotational speed of the exhaust gas turbocharger ( 34 ) the blocking element ( 58 ) from a second position ( 5 ) in one the exhaust gas flow ( 28 ) compared to the second position ( 5 ) more fluidly releasing first position ( 6 ) is moved. Method for operating an internal combustion engine, which has an exhaust gas tract ( 40 ) with at least one exhaust gas flow through the exhaust gas ( 28 ), with at least one with the exhaust gas flow ( 28 ) fluidly connected turbine ( 32 ) of an exhaust gas turbocharger ( 34 ), with one with the exhaust gas flow ( 28 ) fluidly connected exhaust gas recirculation line ( 52 ) for branching off exhaust gas from the exhaust gas flow ( 28 ) and with a relative to the exhaust gas recirculation line and relative to the exhaust gas flow ( 28 ) movable blocking element ( 58 ), by means of which both a flow cross section of the exhaust gas recirculation line through which exhaust gas can flow ( 52 ) as well as a flow cross-section through which the exhaust gas can flow ( 28 ), characterized in that at least one position ( 1 . 2 . 3 . 4 . 5 . 6 ) of the blocking element ( 58 ) depending on at least one operation of the internal combustion engine ( 10 ) characterizing parameter is checked. Method according to Claim 5, characterized in that the parameter is a gas, in particular a state of the gas, of the internal combustion engine ( 10 Characterized. A method according to claim 6, characterized in that the parameter characterizes a pressure of the gas. Method according to one of claims 5 to 7, characterized in that the parameter is a temperature of the internal combustion engine ( 10 Characterized. Method according to one of claims 5 to 8, characterized in that the parameter is a rotational speed of the exhaust gas turbocharger ( 34 Characterized. 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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