DE102015219123A1 - Method for operating a supercharged internal combustion engine with auxiliary drive and internal combustion engine for carrying out such a method - Google Patents

Abstract

Method for operating a supercharged internal combustion engine (1) having - an intake system (2), - an exhaust gas removal system (4, and - at least one exhaust gas turbocharger (6) comprising a turbine (6a) and a compressor (6b), the turbine ( 6a) and the compressor (6b) are arranged on the same rotatable shaft (6c) and the turbine (6a) has a variable turbine geometry in which - in the intake system (2) downstream of the compressor (6b) a throttle valve (10) is arranged, which is actuated by means of an accelerator pedal (9) serving as an actuator, and - an auxiliary drive (7), which is at least drive-connectable with the shaft (6c) of the at least one exhaust-gas turbocharger (6), is provided for assisting the compressor (6b), which additionally provides power for the Actuator of the compressor (6b) provides and delivers to the compressor (6b), - wherein the auxiliary drive (7) is switched on and operated when needed, - the case of need depending on the Position of the accelerator pedal (9) and the rate of adjustment of the accelerator pedal (9) is determined and considered to be given, - additionally provided by the auxiliary drive (7) and the variable geometry of the turbine (6a) are controlled in dependence on each other, and - the variable geometry of the turbine (6a) is set optimized efficiency, the auxiliary drive (7) is used to satisfy as a switchable auxiliary drive (7) a requested power demand.

Description

• – einem Ansaugsystem zum Zuführen von Ladeluft,
• – einem Abgasabführsystem zum Abführen des Abgases, und
• – mindestens einem Abgasturbolader, der eine im Abgasabführsystem angeordnete Turbine und einen im Ansaugsystem angeordneten Verdichter umfasst, wobei die Turbine und der Verdichter auf derselben drehbaren Welle angeordnet sind und die Turbine eine variable Turbinengeometrie aufweist, bei der
• – im Ansaugsystem stromabwärts des Verdichters eine Drosselklappe angeordnet ist, die mittels eines als Aktuator dienenden Gaspedals betätigt wird, und
• – ein mit der Welle des mindestens einen Abgasturboladers zumindest antriebsverbindbarer Hilfsantrieb zur Unterstützung des Verdichters vorgesehen ist, der zusätzlich Leistung für den Antrieb des Verdichters zur Verfügung stellt und an den Verdichter abgibt.

The invention relates to a method for operating a supercharged internal combustion engine with

• An intake system for supplying charge air,
• An exhaust gas discharge system for discharging the exhaust gas, and
• At least one exhaust gas turbocharger comprising a turbine arranged in the exhaust gas removal system and a compressor arranged in the intake system, wherein the turbine and the compressor are arranged on the same rotatable shaft and the turbine has a variable turbine geometry, in which
• - In the intake system downstream of the compressor, a throttle valve is arranged, which is actuated by means of an accelerator pedal serving as an actuator, and
• - Provided with the shaft of the at least one exhaust gas turbocharger at least drive-connected auxiliary drive to support the compressor, which provides additional power for the drive of the compressor and delivers to the compressor.

Furthermore, the invention relates to a supercharged internal combustion engine for carrying out such a method.

A method of the type mentioned and an internal combustion engine for carrying out the method describes, for example, the German patent application DE 10 2012 004 394 A1 ,

An internal combustion engine of the type mentioned with turbocharging and auxiliary drive also describes the US 2013/0209291 A1 , Wherein the auxiliary drive as an electric auxiliary drive supports the compressor of the second exhaust gas turbocharger serving as a high pressure stage, ie can drive. The electric auxiliary drive should be used at low speeds of the engine, ie for small amounts of exhaust gas to support the compressor and provide additional power for the drive of the compressor available to ensure a sufficiently high boost pressure even with small amounts of exhaust gas, if that of the turbine power supplied to the shaft is insufficient to generate the desired boost pressure downstream of the compressor.

An internal combustion engine of the type mentioned is used as a motor vehicle drive. In the context of the present invention, the term internal combustion engine includes diesel engines and gasoline engines, but also hybrid internal combustion engines, which use a hybrid combustion process, and hybrid drives, which in addition to the internal combustion engine comprise an electric motor which can be electrically connected to the internal combustion engine, which receives power from the internal combustion engine or as switchable auxiliary drive additionally delivers power.

In recent years, there has been a trend toward small, supercharged engines, with supercharging primarily a method of increasing performance by compressing the air needed for the engine combustion process. The economic importance of these engines for the automotive industry continues to increase.

Frequently, an exhaust gas turbocharger is used for charging, in which a compressor and a turbine are arranged on the same shaft. The hot exhaust stream is supplied to the turbine and relaxes with energy release in the turbine, causing the shaft to rotate. The energy emitted by the exhaust gas flow to the turbine and finally to the shaft is used to drive the compressor, which is also arranged on the shaft. The compressor conveys and compresses the charge air supplied to it, whereby a charging of the cylinder is achieved. Advantageously, a charge air cooler is provided downstream of the compressor in the intake system, with which the compressed charge air is cooled before entering the at least one cylinder. The radiator lowers the temperature and thus increases the density of the charge air, so that the cooler to a better filling of the cylinder, d. H. contributes to a larger air mass. There is a compaction by cooling.

The advantage of an exhaust gas turbocharger compared to a mechanical supercharger is that there is no mechanical connection to the power transmission between the supercharger and the internal combustion engine or is required. While a mechanical supercharger obtains the energy required for its drive completely from the internal combustion engine and thus reduces the power provided and thus adversely affects the efficiency, the exhaust gas turbocharger uses the exhaust gas energy of the hot exhaust gases.

The charge is - as already mentioned - the increase in performance. The air required for the combustion process is compressed, which allows each cylinder per working cycle, a larger air mass can be supplied. As a result, the fuel mass and thus the medium pressure can be increased.

The charge is a suitable means to increase the capacity of an internal combustion engine with unchanged displacement or to reduce the displacement at the same power. In any case, the charging leads to an increase in space performance and a lower power mass. Will the Decreasing displacement, so can shift the load collective towards higher loads, where the specific fuel consumption is lower. By charging in combination with suitable transmission designs and a so-called downspeeding can be realized, in which also a lower specific fuel consumption can be achieved.

Charging thus supports the constant effort in the development of internal combustion engines to minimize fuel consumption, d. H. to improve the efficiency of the internal combustion engine.

Another fundamental goal is to reduce pollutant emissions. In the solution of this task, the charging can also be effective. With targeted design of the charge namely benefits in efficiency and in the exhaust emissions can be achieved.

The interpretation of the turbocharger turbocharger is difficult, with basically a noticeable increase in performance in all speed ranges is sought. In the prior art, however, a strong torque drop is observed when falling below a certain speed. This effect is undesirable. This torque drop becomes understandable if it is taken into account that the boost pressure ratio depends on the turbine pressure ratio. If the engine speed is reduced, this leads to a smaller exhaust gas mass flow and thus to a smaller turbine pressure ratio. Consequently, the boost pressure ratio also decreases toward lower speeds. This is synonymous with a torque drop.

In practice, the relationships described above often result in a small exhaust gas turbocharger, i. H. an exhaust gas turbocharger with a small turbine cross section is used, whereby the turbine pressure ratio can be increased. However, this worsens the charge at higher speeds and shifts the torque drop only towards lower speeds. In addition, this approach, d. H. the reduction of the turbine cross-section limits, since the desired charging and performance increase should be possible without restriction and to the desired extent, even at high speeds.

The torque characteristic of a supercharged internal combustion engine is tried to improve in the prior art by various measures.

For example, by a small design of the turbine cross-section and simultaneous Abgasabblasung, the Abgasabblasung example, by means of boost pressure or by exhaust pressure, but also can be controlled electrically. For this purpose, the turbine is equipped with a blow-off line which branches off from the exhaust-gas removal system upstream of the turbine and in which a shut-off element is arranged. Such a turbine is also referred to as a waste gate turbine. If the exhaust gas mass flow exceeds a critical size, part of the exhaust gas flow is guided past the turbine via the blow-off line as part of the so-called exhaust gas blow-off, d. H. blown off. This approach has the disadvantage that the high-energy blown exhaust gas remains unused and the charging behavior is regularly insufficient at higher speeds.

By opening the blow-off line more or less widely, the amount of exhaust gas passed past the turbine can be adjusted, and by means of the amount of exhaust gas carried past the turbine, in turn, the boost pressure downstream of the compressor can be influenced, ie. H. control, in particular limit.

A turbine with variable turbine geometry allows a further adaptation to the respective operating point of the internal combustion engine by adjusting the turbine geometry or the effective turbine cross-section, to some extent a speed-dependent or load-dependent control of the turbine geometry can be done.

In this case, guide vanes for influencing the flow direction are arranged in the inlet region of the turbine. Unlike the vanes of the rotating impeller, the vanes do not rotate with the shaft of the turbine.

If the turbine has a fixed invariable geometry, the vanes, if present, are not only stationary, but also completely immovable in the entry area, i. H. rigidly fixed. If, on the other hand, a turbine with variable geometry is used, the vanes are indeed arranged stationary, but not completely immobile, but rotatable about their axis, so that the flow of the blades can be influenced.

The internal combustion engine, which is the subject of the present invention, has at least one exhaust-gas turbocharger for charging purposes.

The torque characteristic of a supercharged internal combustion engine may be increased by a plurality of turbochargers arranged in parallel, i. H. be improved by a plurality of parallel turbines of smaller turbine cross-section, with turbines are switched successively with increasing exhaust gas quantity; similar to a register charge.

The torque characteristic can also be advantageously influenced by means of a plurality of exhaust-gas turbochargers connected in series. By switching in series of two exhaust gas turbochargers, one of which is an exhaust gas turbocharger as a high pressure stage and an exhaust gas turbocharger as a low pressure stage, the compressor map can be widened in an advantageous manner, both towards smaller compressor streams as well as towards larger compressor streams.

In particular, in the case of the exhaust-gas turbocharger serving as a high-pressure stage, the pumping limit can be shifted toward smaller compressor flows, which means that high boost pressure ratios can be achieved even with small compressor flows and the torque characteristic in the lower rpm range is markedly improved. This is achieved by designing the high-pressure turbine for small exhaust gas mass flows and providing a blow-off line with which exhaust gas is increasingly conducted past the high-pressure turbine as the exhaust gas mass flow increases. For this purpose, the blow-off line branches off the exhaust-gas removal system upstream of the high-pressure turbine and returns into the exhaust-gas removal system upstream of the low-pressure turbine. In the blow-off line, a shut-off element is arranged in order to control the exhaust gas flow conducted past the high-pressure turbine.

Against the background of the above, it is an object of the present invention to provide a method according to the preamble of claim 1 for operating a charge by turbocharger supercharged internal combustion engine, in which a provided to support the compressor auxiliary drive is operated and switched on demand.

Another object of the present invention is to provide an internal combustion engine for carrying out such a method.

• – einem Ansaugsystem zum Zuführen von Ladeluft,
• – einem Abgasabführsystem zum Abführen des Abgases, und
• – mindestens einem Abgasturbolader, der eine im Abgasabführsystem angeordnete Turbine und einen im Ansaugsystem angeordneten Verdichter umfasst, wobei die Turbine und der Verdichter auf derselben drehbaren Welle angeordnet sind und die Turbine eine variable Turbinengeometrie aufweist, bei der
• – im Ansaugsystem stromabwärts des Verdichters eine Drosselklappe angeordnet ist, die mittels eines als Aktuator dienenden Gaspedals betätigt wird, und
• – ein mit der Welle des mindestens einen Abgasturboladers zumindest antriebsverbindbarer Hilfsantrieb zur Unterstützung des Verdichters vorgesehen ist, der zusätzlich Leistung für den Antrieb des Verdichters zur Verfügung stellt und an den Verdichter abgibt,

das dadurch gekennzeichnet ist, dass

• – der Hilfsantrieb im Bedarfsfall zugeschaltet und betrieben wird, wobei der Bedarfsfall in Abhängigkeit von der Stellung des Gaspedals und der Verstellrate des Gaspedals festgestellt und als gegeben angesehen wird,
• – die vom Hilfsantrieb zusätzlich zur Verfügung gestellte Leistung und die variable Geometrie der Turbine in Abhängigkeit voneinander gesteuert werden, und
• – die variable Geometrie der Turbine wirkungsgradoptimiert eingestellt wird, wobei der Hilfsantrieb verwendet wird, um als zuschaltbarer Hilfsantrieb einen angeforderten Leistungsmehrbedarf zu befriedigen.

The first sub-task is solved by a method for operating a supercharged internal combustion engine with

• An intake system for supplying charge air,
• An exhaust gas discharge system for discharging the exhaust gas, and
• At least one exhaust gas turbocharger comprising a turbine arranged in the exhaust gas removal system and a compressor arranged in the intake system, wherein the turbine and the compressor are arranged on the same rotatable shaft and the turbine has a variable turbine geometry, in which
• - In the intake system downstream of the compressor, a throttle valve is arranged, which is actuated by means of an accelerator pedal serving as an actuator, and
• A auxiliary drive, which is at least drive-connectable with the shaft of the at least one exhaust-gas turbocharger, is provided for assisting the compressor, which additionally provides power for driving the compressor and delivers it to the compressor,

which is characterized in that

• - If necessary, the auxiliary drive is switched on and operated, wherein the case of need is determined in dependence on the position of the accelerator pedal and the adjustment rate of the accelerator pedal and considered given,
• - The additionally provided by the auxiliary drive power and the variable geometry of the turbine are controlled in dependence on each other, and
• - The variable geometry of the turbine is set optimized efficiency, the auxiliary drive is used to meet as a switchable auxiliary drive a requested power demand.

In accordance with the method according to the invention, the auxiliary drive connected to the shaft for assisting the exhaust-gas turbocharger is switched on and operated only when necessary in order to additionally provide power for driving the compressor, which can not be provided by the turbine.

The need case is determined depending on the position of the accelerator pedal and the adjustment rate of the accelerator pedal, d. H. detected, wherein a specific pair of values comprising the position and the Verstellrate of the accelerator pedal, the specific information is assigned, if there is a need or no need exists. In this respect, using the at least two mentioned input variables, namely the position of the accelerator pedal and the adjustment rate of the accelerator pedal, for example from an at least three-dimensional characteristic map or from at least one lockup table, the gas pedal-specific information, "case of need" or "no case of need", as output variable be read out. The adjustment of the pivotable accelerator pedal defines itself as adjustment angle per unit time.

The procedure according to the invention for operating the auxiliary drive uses the fact that a load change, in particular a sudden increase in load demand, and its urgency in the type of operation of the accelerator pedal can be seen, with a high Verstellrate the pivoting accelerator pedal serves as an indication of a sudden increase in load and is scored. Taking into account the current position of the accelerator pedal then traded if necessary.

If an increased load demand on the part of the driver is detected, because the adjustment rate exceeds a predefinable adjustment rate, the auxiliary drive is switched on taking into account the current position of the accelerator pedal or operated in support of the compressor to provide additional drive power for the compressor. The position of the accelerator pedal is important because a connection of the auxiliary drive does not always make sense even at high Verstellrate under all circumstances, that is, for example, when the accelerator pedal already operated at 50% or 75% of its maximum adjustment or its maximum adjustment or has been pivoted.

To influence the boost pressure downstream of the compressor by means of auxiliary drive, in particular to increase, has advantages over other measures. So can be taken much faster influence on the boost pressure by means of an auxiliary drive than is possible by means of turbine exhaust side. If the boost pressure is to be increased rapidly, this can be done faster by activating the auxiliary drive than by increasing the exhaust gas quantity. A control that intervenes on the exhaust side to achieve a change in the boost pressure on the intake side, in principle, has a worse response than if directly by activating the auxiliary drive, the compressor performance is increased.

With the ability to increase the power provided for the drive of the compressor available almost instantaneously, the response and thus the performance of the exhaust gas turbocharger and thus the internal combustion engine can be significantly improved.

According to the invention, the turbine of the at least one exhaust gas turbocharger is equipped with a variable turbine geometry. The power additionally provided by the auxiliary drive and the variable geometry of the turbine are controlled in dependence on each other. A one-sided dependency in which the additional power provided by the auxiliary drive is controlled as a function of the geometry of the turbine is sufficient, since the variable geometry of the turbine is adjusted according to the present invention to optimize efficiency and the auxiliary drive is used to as a switchable auxiliary drive to a requested power demand to satisfy.

If the geometry of the turbine is selected and adjusted with regard to the highest possible efficiency and not with regard to the power provided and requested on the shaft, corrective action can be taken by means of an auxiliary drive.

If the variable geometry turbine provides less power to the shaft than required, the auxiliary drive, as a switchable auxiliary drive, can provide additional power to drive the compressor.

With the method according to the invention, the first object underlying the invention is achieved, namely a method according to the claim 1, in which a provided for supporting the compressor auxiliary drive is operated and switched on demand.

Advantageous embodiments of the method according to the invention, in which the load of the internal combustion engine is controlled and adjusted by means of the throttle valve. While the injected fuel quantity is used to adjust the air ratio λ, the load or power in the gasoline engine is controlled and adjusted by means of a throttle valve arranged in the intake system. By adjusting the throttle, the pressure of the intake air behind the throttle valve can be reduced more or less. The farther the throttle is closed, d. H. the more this obstructs the intake system, the higher the pressure loss of the intake air across the throttle and the lower the pressure of the intake air downstream of the throttle and before the intake into the at least one cylinder, d. H. Combustion chamber. With a constant combustion chamber volume, the air mass, d. H. the quantity will be set. This is also the reason why the quantity control proves to be disadvantageous, especially in part-load operation, because low loads require high throttling and pressure reduction in the intake system, whereby the charge exchange losses increase with decreasing load and increasing throttling.

Further advantageous embodiments of the method according to the invention are discussed in connection with the subclaims.

Advantageous embodiments of the method according to the invention, in which the auxiliary drive is switched on and operated when needed, wherein the need is determined in dependence on the position of the throttle and the Verstellrate the throttle and considered to exist.

The throttle valve is actuated by means of an accelerator pedal, which serves as an actuator. In this respect, it can be concluded from the position of the throttle valve on the position of the accelerator pedal and by the adjustment rate of the throttle valve on the adjustment of the accelerator pedal and vice versa.

The method variant in question thus describes an indirect, indirect procedure in which, starting from the throttle valve, the gas pedal is closed. The adjustment of the pivotable throttle again defines itself as adjustment angle per unit time. An increased load request is assumed, taking into account the instantaneous position of the throttle valve, when a correspondingly high adjustment rate of the pivotable throttle valve is present, ie detected.

Embodiments of the method according to the invention in which a mechanically driven auxiliary drive is used as an auxiliary drive are advantageous.

Advantageous embodiments of the method according to the invention, in which an electrically driven electric machine is used as an auxiliary drive. In contrast to a mechanically driven auxiliary drive no mechanical connection to the internal combustion engine is required. In addition, an electric machine can serve as an auxiliary drive and as a generator. The power consumed by the electric machine as a generator can be stored and, if necessary, used to drive the electric machine serving as an auxiliary drive, i. H. be used.

Advantageous in this context, therefore, embodiments of the method according to the invention, in which the drive connected to the shaft electric machine is operated as a generator and receives power from the turbine, whereby the power provided for the drive of the compressor from the turbine power is reduced and the boost pressure is lowered downstream of the compressor.

According to the invention, the electric machine which can be drive-connected to the shaft does not have to be a priori usable as a generator, but can be operated as an auxiliary drive. In this respect, the above embodiment is only an advantageous variant. An electric machine that can only be operated as an auxiliary drive is completely sufficient for carrying out the method according to the invention.

In the present case, the electric machine of the internal combustion engine according to the invention is initially not used as an electric auxiliary drive for the compressor of the exhaust gas turbocharger, but in case of need, d. H. at least temporarily, used as a generator and operated to recover or recover electrical energy, d. H. Convert exhaust gas energy into electrical energy.

The energy emitted by the exhaust gas flow to the turbine and finally to the shaft is consequently not used exclusively for driving the compressor arranged on the shaft, but is at least partially taken up by the electric machine operated as a generator.

Blowing off exhaust gas for controlling or limiting the boost pressure downstream of the compressor is thus eliminated or is no longer necessary, which is why the turbine of the at least one exhaust gas turbocharger according to the invention basically does not have to be equipped with a blow-off line, whereby the turbocharger is simplified, more compact and less expensive ,

The fact that the electric machine operated as a generator receives power from the turbine, the power provided by the turbine for driving the compressor is reduced. The boost pressure downstream of the compressor can be controlled in this way by the power absorbed by the electric machine, in particular reduce and limit.

With the Abgasabblasung accounts not only the Abblaseleitung, but also the blowing off as such and thus the waste of high-energy exhaust gas due to blow-off. Because the surplus power provided by the turbine on the shaft is no longer disposed of unused by blow-off, d. H. must be reduced, but can be converted into electrical energy by means of a generator operated electric machine, the efficiency of the exhaust gas turbocharger and the internal combustion engine can be significantly improved.

Controlling the boost pressure downstream of the compressor by means of the power consumed by the electric machine has further advantages. Thus, by means of electric machine much faster influence on the boost pressure can be taken as this is possible by means of Abgasabblasung. If the charge pressure is to be lowered rapidly, this can be done faster by activating the electric machine than by opening a blow-off line. A controller that engages the exhaust side to achieve a change in the boost pressure on the intake side, in principle, has a poorer response than when directly by activating the electric machine, the compressor performance is reduced.

With the ability to reduce the power provided for the drive of the compressor available almost instantaneously, the response and thus the performance of the exhaust turbocharging and thus the internal combustion engine can be significantly improved.

The above-described relationships are important both in terms of limiting the boost pressure and in terms of the rapid reduction of the boost pressure during a load change in the context of transient, ie transient operation of the internal combustion engine.

In this context, embodiments of the method according to the invention in which the power consumed by the generator is stored as electrical energy in a battery are advantageous.

This variant of the method has the advantage that the power obtained by means of generator operation does not have to be used immediately but can be stored. In an electric machine, which can also be used and operated as a switchable auxiliary drive, the energy stored in the battery is then preferably used to drive the auxiliary drive, without additional energy would have to be provided, which could possibly increase the fuel consumption of the internal combustion engine.

For operating a supercharged internal combustion engine in which the turbine of the at least one exhaust gas turbocharger comprises a blow-off line which branches off from the exhaust gas removal system upstream of the turbine and in which a shut-off element is arranged, embodiments of the method according to the invention in which the blow-off line is opened to exhaust gas are advantageous bypassing the turbine, thereby reducing the power provided by the turbine to the shaft.

Even if the internal combustion engine according to the invention does not have to be equipped a priori with a blow-off line and a generator or an electric machine as an auxiliary drive makes it possible to dispense with such a line, it may be advantageous to provide a Abgasabblasung, namely, for example, in the event that a designated battery has reached its maximum state of charge or, for another reason, there is no need for generator-generated electrical energy.

For operating a supercharged internal combustion engine in which an electrically driven electric machine is used as an auxiliary drive, embodiments of the method according to the invention are advantageous, which are characterized in that the Abblaseleitung is closed when the electric machine is operated as a generator and receives power from the turbine.

As long as a designated battery has not reached its maximum state of charge or there is a need for generated by generator electrical energy, the blow-off should be closed so as not to waste unnecessarily high-energy exhaust gas, but to use the energy contained in the hot exhaust gas turbine and generator and convert into electrical energy.

For operating a supercharged internal combustion engine, in which an electrically driven electric machine is used as auxiliary drive, embodiments of the method according to the invention are advantageous, which are characterized in that the power absorbed by the electric machine as a generator and the past the turbine via discharge line exhaust gas in dependence on each other to be controlled.

A one-sided dependency in which the power consumed by the electric machine as a generator is controlled as a function of the amount of exhaust gas blown off or the amount of exhaust gas blown off as a function of the power consumed by the electric machine as the generator is sufficient.

The power provided by the turbine to the shaft can be adjusted by blowing off exhaust gas, i. H. can be controlled, and can be further reduced by means of a generator operated electric machine. The power provided for driving the compressor can thus be adjusted by means of the two control variables mentioned above, ie. H. by electric machine and blow-off line.

Further advantageous embodiments of the method according to the invention, in which the power absorbed by the electric machine as a generator and the position of the throttle valve are controlled in dependence on each other. There must be no interdependence. A one-sided dependence in which the power absorbed by the electric machine as a generator is controlled as a function of the position of the throttle valve or the position of the throttle valve as a function of the power consumed by the electric machine as a generator, is sufficient.

The boost pressure downstream of the throttle depends on the boost pressure upstream of the throttle and the position of the throttle itself, wherein the boost pressure upstream of the throttle depends primarily on the drive power provided to the compressor, which depends on the exhaust gas amount and / or the electric machine set the power consumed as a generator, d. H. can control.

As a result, advantageous embodiments of the method according to the invention, in which the boost pressure downstream of the throttle valve by means of the electric machine as a generator recorded power and the position of the throttle valve is controlled and adjusted. The recorded by the electric machine as a generator power and the position of the throttle are controlled in dependence on each other, with a one-sided dependence is sufficient.

For operating a supercharged internal combustion engine in which the turbine of the at least one exhaust gas turbocharger has a variable turbine geometry and as an auxiliary drive an electrically driven electric machine is used, embodiments of the method according to the invention are advantageous, which are characterized in that the power absorbed by the electric machine as a generator and the variable geometry of the turbine are controlled in dependence of each other. A one-sided dependency in which the power consumed by the electric machine as a generator is controlled as a function of the geometry of the turbine or the geometry of the turbine as a function of the power consumed by the electric machine as a generator, is sufficient.

The power provided by the turbine to the shaft can be adjusted, in particular increased or decreased, by adjusting the turbine geometry, whereby the power provided for driving the compressor is further reduced by means of a generator-operated electric machine, i. H. can be set.

In this connection, embodiments of the method according to the invention in which the variable geometry of the turbine is adjusted in an efficiency-optimized manner are advantageous, wherein the electric machine is used to record a power surplus provided by the turbine as a switchable generator.

If the geometry of the turbine is selected and set with regard to the highest possible efficiency and not with regard to the power provided on the shaft, corrective action can be taken by means of an electric motor.

If more power is provided to the shaft than intended by the efficiency-optimized operation of the turbine, the power provided on the shaft can be reduced by means of the power consumed by the electric machine as a generator.

Advantageous embodiments of the method according to the invention, in which, starting from a driven as a generator electric machine in the operation as a switchable auxiliary drive is changed as soon as the need for support of the drive of the compressor is present and found. For the presence of a need, i. H. With regard to the case of need, reference is made to the statements made above.

• – einem Ansaugsystem zum Zuführen von Ladeluft,
• – einem Abgasabführsystem zum Abführen des Abgases, und
• – mindestens einem Abgasturbolader, der eine im Abgasabführsystem angeordnete Turbine und einen im Ansaugsystem angeordneten Verdichter umfasst, wobei die Turbine und der Verdichter auf derselben drehbaren Welle angeordnet sind und die Turbine eine variable Turbinengeometrie aufweist, bei der
• – im Ansaugsystem stromabwärts des Verdichters eine Drosselklappe angeordnet ist, die mittels eines als Aktuator dienenden Gaspedals betätigt wird, und
• – ein mit der Welle des mindestens einen Abgasturboladers zumindest antriebsverbindbarer Hilfsantrieb zur Unterstützung des Verdichters vorgesehen ist, der zusätzlich Leistung für den Antrieb des Verdichters zur Verfügung stellt und an den Verdichter abgibt,

und die dadurch gekennzeichnet ist, dass

• – der Hilfsantrieb sowohl verwendbar ist als zuschaltbarer Hilfsantrieb zur Befriedigung eines angeforderten Leistungsmehrbedarfs für den Antrieb des Verdichters als auch verwendbar ist als Generator zur Leistungsaufnahme von der Turbine.

The second sub-task on which the invention is based, namely to provide an internal combustion engine for carrying out a method of the type described above, is solved by an internal combustion engine

• An intake system for supplying charge air,
• An exhaust gas discharge system for discharging the exhaust gas, and
• At least one exhaust gas turbocharger comprising a turbine arranged in the exhaust gas removal system and a compressor arranged in the intake system, wherein the turbine and the compressor are arranged on the same rotatable shaft and the turbine has a variable turbine geometry, in which
• - In the intake system downstream of the compressor, a throttle valve is arranged, which is actuated by means of an accelerator pedal serving as an actuator, and
• A auxiliary drive, which is at least drive-connectable with the shaft of the at least one exhaust-gas turbocharger, is provided for assisting the compressor, which additionally provides power for driving the compressor and delivers it to the compressor,

and which is characterized in that

• - The auxiliary drive is both usable as a switchable auxiliary drive to satisfy a required power demand for the drive of the compressor as well as usable as a generator for power consumption of the turbine.

The statements already made for the method according to the invention also apply to the internal combustion engine according to the invention, which is why reference is generally made at this point to the statements made above with regard to the method according to the invention. The different process variants sometimes require different internal combustion engines.

An engine controller of the internal combustion engine is set up and adapted such that the auxiliary power provided by the auxiliary drive and the variable geometry of the turbine are controlled in dependence on each other, the variable geometry of the turbine is set to optimize efficiency and the auxiliary drive is used to switchable auxiliary drive to meet a requested power demand.

Embodiments of the internal combustion engine in which a charge air cooler is arranged in the intake system downstream of the compressor of the at least one exhaust gas turbocharger are advantageous. The charge air cooler lowers the air temperature and thus increases the density of the air, whereby the cooler also contributes to a better filling of the combustion chamber with air, ie to a larger air mass.

Embodiments of the supercharged internal combustion engine in which exhaust gas recirculation is provided are advantageous.

Advantageous in this connection are embodiments of the supercharged internal combustion engine in which an exhaust gas recirculation is provided which comprises a line which branches off the exhaust gas removal system upstream of the turbine of the at least one exhaust gas turbocharger and opens into the intake system, preferably downstream of the compressor of the at least one exhaust gas turbocharger.

To comply with future limits for nitrogen oxide emissions, an exhaust gas recirculation is increasingly used, ie the return of exhaust gases from the exhaust side to the inlet side, in which the nitrogen oxide emissions can be significantly reduced with increasing exhaust gas recirculation rate. In this case, the exhaust gas recirculation rate x _{AGR is} determined by x _AGR = m _AGR / (m _AGR + m _{fresh air} ), where m _{AGR designates} the mass of recirculated exhaust gas and m _{fresh air} the supplied fresh air or combustion air, possibly guided and compressed by a compressor.

Exhaust gas recirculation is also suitable for reducing emissions of unburned hydrocarbons in the partial load range. In order to achieve a significant reduction in nitrogen oxide emissions, high exhaust gas recirculation rates may be required, which may be on the order of x _AGR ≈ 60% to 70%.

Embodiments in which the line for exhaust gas recirculation leads downstream of a charge air cooler into the intake system are advantageous. In this way, the exhaust gas flow is not passed through the intercooler and consequently can not pollute this radiator by deposits of pollutants contained in the exhaust stream, in particular soot particles and oil.

Embodiments in which an additional cooler is provided in the exhaust gas recirculation line are advantageous. This additional cooler lowers the temperature in the hot exhaust gas flow and thus increases the density of the exhaust gases. The temperature of the cylinder fresh charge, which occurs in the mixture of fresh air with the recirculated exhaust gases, is consequently further reduced, whereby the additional radiator contributes to a better filling of the combustion chamber with charge air.

Embodiments in which a shut-off element is provided in the line for exhaust gas recirculation are advantageous. This shut-off element is used to control the exhaust gas recirculation rate.

Also advantageous are embodiments of the supercharged internal combustion engine, in which an exhaust gas recirculation is provided which comprises a line which branches off from the Abgasabführsystem downstream of the turbine of the at least one exhaust gas turbocharger and opens into the intake system, preferably upstream of the compressor of the at least one exhaust gas turbocharger.

In contrast to the high-pressure EGR already mentioned, which removes exhaust gas from the exhaust gas removal system upstream of the turbine and introduces it into the intake system downstream of the compressor, in a low-pressure EGR exhaust gas is returned to the inlet side, which has already passed through the turbine. For this purpose, the low-pressure EGR comprises a return line, which branches off downstream of the turbine from the Abgasabführsystem and opens upstream of the compressor in the intake system.

The exhaust gas, which is returned to the inlet side by means of low-pressure EGR and is preferably cooled, is mixed with fresh air upstream of the compressor. The mixture of fresh air and recirculated exhaust gas produced in this way forms the charge air, which is supplied to the compressor and compressed.

It is harmless that in the context of low-pressure EGR exhaust gas is passed through the compressor, since exhaust gas is usually used, which downstream of the turbine exhaust after-treatment, in particular in the particulate filter was subjected. Deposits in the compressor, which change the geometry of the compressor, in particular the flow cross-sections, and thus worsen the efficiency of the compressor, are therefore not to be feared.

Embodiments of the internal combustion engine in which a shut-off element used is a valve or a throttle valve are advantageous.

In this case, embodiments in which the shut-off element is electrically, hydraulically, pneumatically, mechanically or magnetically controllable, preferably by means of motor control, are advantageous.

In the following the invention is based on an embodiment according to 1 described in more detail. Hereby shows:

1 schematically a first embodiment of the internal combustion engine.

1 shows a first embodiment of the supercharged internal combustion engine 1 the example of a four-cylinder in-line engine 1 ,

For discharging the hot exhaust gases have the four cylinders arranged in series 3 via an exhaust gas removal system 4 , Furthermore, the cylinders have 3 via an intake system 2 for supplying charge air.

The internal combustion engine 1 is with an exhaust gas turbocharger 6 equipped, the one in the exhaust system 4 arranged turbine 6a and one in the intake system 2 arranged compressor 6b includes, the turbine 6a and the compressor 6b on the same rotatable shaft 6c are arranged.

Downstream of the compressor 6b is a charge air cooler 5 in the intake system 2 arranged. The intercooler 5 lowers the charge air temperature and thus increases the density of the air, which is why the radiator 5 to a better filling of the cylinder 3 contributes with charge air. Furthermore, in the intake system 2 downstream of the compressor 6b and the intercooler 5 a throttle 10 arranged, the control and adjustment of the load of the internal combustion engine 1 serves and by means of an accelerator pedal serving as an actuator 9 is pressed.

The internal combustion engine 1 may further be provided with an exhaust gas recirculation, which includes a line upstream and downstream of the turbine 6a , from the exhaust gas removal system 4 branches off and downstream or upstream of the compressor 6b into the intake system 2 flows (not shown).

The turbine 6a is with a blow-off line 8th equipped, the upstream of the turbine 6a from the exhaust system 4 branches off and downstream of the turbine 6a back into the exhaust system 4 opens and in the a shut-off 8a is arranged. This is the turbine 6a designed as a so-called waste gate turbine.

By a more or less wide opening of the blow-off line 8th can the at the turbine 6a be adjusted exhaust gas amount, wherein the boost pressure downstream of the compressor 6b by means of the turbine 6a influence the amount of exhaust gas passed, ie control, in particular limits.

One with the wave 6c the exhaust gas turbocharger 6 drive-connected auxiliary drive 7 settles in support of the compressor 6b use. The as auxiliary drive 7 serving electric machine 7a puts on the shaft 6c additional power for the drive of the compressor 6b to disposal.

The electric machine 7a is switched on and operated if necessary. The requirement is dependent on the position of the accelerator pedal 9 and the rate of adjustment of the accelerator pedal 9 detected, ie detected. The turbine 6a , which is equipped with a variable turbine geometry, it is operated efficiency optimized (not shown).

The electric machine 7a can also operate as a generator, the power of the turbine 6a absorbs, so that from the turbine 6a for driving the compressor 6b provided service is reduced. The boost pressure downstream of the compressor 6b will be reduced. The power consumed by the generator can be stored as electrical energy in a battery (not shown).

LIST OF REFERENCE NUMBERS

1

 supercharged internal combustion engine, four-cylinder in-line engine

2

 intake system

3

 cylinder

4

 Abgasabführsystem

5

 Intercooler

6

 turbocharger

6a

 turbine

6b

 compressor

6c

 wave

7

 auxiliary drive

7a

 electric machine

8th

 blow-off line

8a

 shut-off

9

 accelerator

10

 throttle

QUOTES INCLUDE IN THE DESCRIPTION

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

Cited patent literature

• DE 102012004394 A [0003]
• US 2013/0209291 A1 [0004]

Claims (15)

Method for operating a supercharged internal combustion engine ( 1 ) with an intake system ( 2 ) for supplying charge air, - an exhaust gas removal system ( 4 ) for discharging the exhaust gas, and - at least one exhaust gas turbocharger ( 6 ), one in the exhaust system ( 4 ) arranged turbine ( 6a ) and one in the intake system ( 2 ) arranged compressors ( 6b ), wherein the turbine ( 6a ) and the compressor ( 6b ) on the same rotatable shaft ( 6c ) are arranged and the turbine ( 6a ) has a variable turbine geometry, in which - in the intake system ( 2 ) downstream of the compressor ( 6b ) a throttle valve ( 10 ) is arranged, which by means of an accelerator pedal serving as an actuator ( 9 ), and - one with the shaft ( 6c ) of the at least one exhaust gas turbocharger ( 6 ) at least drive-connected auxiliary drive ( 7 ) to support the compressor ( 6b ) is provided, the additional power for the drive of the compressor ( 6b ) and to the compressor ( 6b ), - the auxiliary drive ( 7 ) is switched on and operated if necessary, the need, depending on the position of the accelerator pedal ( 9 ) and the adjustment rate of the accelerator pedal ( 9 ) and considered as given. characterized in that - the auxiliary drive ( 7 ) is switched on and operated if necessary, the need, depending on the position of the accelerator pedal ( 9 ) and the adjustment rate of the accelerator pedal ( 9 ) and considered as given, - that of the auxiliary drive ( 7 ) additionally provided power and the variable geometry of the turbine ( 6a ) are controlled in dependence on each other, and - the variable geometry of the turbine ( 6a ) is set optimized efficiency, wherein the auxiliary drive ( 7 ) is used as a connectable auxiliary drive ( 7 ) to meet a requested additional power demand. Method according to claim 1, characterized in that the auxiliary drive ( 7 ) is switched on and operated if necessary, the need, depending on the position of the throttle valve ( 10 ) and the adjustment rate of the throttle valve ( 10 ) and considered as given. Method according to claim 1 or 2, characterized in that as auxiliary drive ( 7 ) a mechanically driven auxiliary drive ( 7 ) is used. Method according to claim 1 or 2, characterized in that as auxiliary drive ( 7 ) an electrically driven electric machine ( 7a ) is used. A method according to claim 4, characterized in that the with the shaft ( 6c ) drive-connected electric machine ( 7a ) is operated as a generator and power from the turbine ( 6a ), whereby the for the drive of the compressor ( 6b ) from the turbine ( 6a ) and the charge pressure downstream of the compressor ( 6b ) is lowered. A method according to claim 5, characterized in that the power absorbed by the generator as electrical energy in a battery ( 9 ) is stored. Method according to one of the preceding claims for operating a supercharged internal combustion engine ( 1 ), in which the turbine ( 6a ) of the at least one exhaust gas turbocharger ( 6 ) a blow-off line ( 8th ), which upstream of the turbine ( 6a ) from the exhaust gas removal system ( 4 ) and in which a shut-off element ( 8a ), characterized in that the blow-off line ( 8th ) is opened to exhaust gas on the turbine ( 6a ), whereby the turbine ( 6a ) on the shaft ( 6c ) is reduced. Method according to claim 7 for operating a supercharged internal combustion engine ( 1 ), in which as auxiliary drive ( 7 ) an electrically driven electric machine ( 7a ) is used, characterized in that the blow-off line ( 8th ) is closed when the electric machine ( 7a ) is operated as a generator and power from the turbine ( 6a ). Method according to claim 7 for operating a supercharged internal combustion engine ( 1 ), in which as auxiliary drive ( 7 ) an electrically driven electric machine ( 7a ) is used, characterized in that the of the electric machine ( 7a ) power consumed as a generator and that at the turbine ( 6a ) via blow-off line ( 8th ) Passed amount of exhaust gas are controlled in dependence on each other. Method according to one of claims 5 to 9, characterized in that the of the electric machine ( 7a ) power taken up as a generator and the position of the throttle valve ( 10 ) are controlled in dependence on each other. A method according to claim 10, characterized in that the boost pressure downstream of the throttle valve ( 10 ) by means of the electric machine ( 7a ) as a generator recorded power and the position of the throttle valve ( 10 ) is controlled and adjusted. Method according to one of the preceding claims for operating a supercharged internal combustion engine ( 1 ), in which the turbine ( 6a ) of the at least one exhaust gas turbocharger ( 6 ) has a variable turbine geometry and as an auxiliary drive ( 7 ) an electrically driven electric machine ( 7a ) is used, characterized in that the of the electric machine ( 7a ) power consumed as a generator and the variable geometry of the turbine ( 6a ) are controlled in dependence on each other. A method according to claim 12, characterized in that the variable geometry of the turbine ( 6a ) is adjusted efficiency-optimized, wherein the electric machine ( 7a ) is used as a switchable generator one of the turbine ( 6a ) to include the surplus provided. Method according to one of claims 5 to 13, characterized in that starting from an electric machine operated as a generator ( 7a ) into operation as a switchable auxiliary drive ( 7 ) as soon as the need arises for supporting the drive of the compressor ( 6b ) and is found. Charged internal combustion engine ( 1 ) for carrying out a method according to one of the preceding claims, comprising - an intake system ( 2 ) for supplying charge air, - an exhaust gas removal system ( 4 ) for discharging the exhaust gas, and - at least one exhaust gas turbocharger ( 6 ), one in the exhaust system ( 4 ) arranged turbine ( 6a ) and one in the intake system ( 2 ) arranged compressors ( 6b ), wherein the turbine ( 6a ) and the compressor ( 6b ) on the same rotatable shaft ( 6c ) are arranged and the turbine ( 6a ) has a variable turbine geometry, in which - in the intake system ( 2 ) downstream of the compressor ( 6b ) a throttle valve ( 10 ) is arranged, which by means of an accelerator pedal serving as an actuator ( 9 ), and - one with the shaft ( 6c ) of the at least one exhaust gas turbocharger ( 6 ) at least drive-connected auxiliary drive ( 7 ) to support the compressor ( 6b ) is provided, the additional power for the drive of the compressor ( 6b ) and to the compressor ( 6b ), characterized in that - the auxiliary drive ( 7 ) can be used both as a switchable auxiliary drive ( 7 ) to satisfy a requested additional power requirement for the drive of the compressor ( 6b ) as well as usable as generator for the power consumption of the turbine ( 6a ).

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