DE102014208703A1 - Exhaust-driven turbocharged internal combustion engine with at least two turbines and method for operating such an internal combustion engine - Google Patents

Abstract

Supercharged internal combustion engine (1) with at least one cylinder head (2) with at least two cylinders (3), in which - each cylinder (3) has at least two outlet openings (4a, 4b), of which at least one outlet opening (4a) which can be connected is formed, wherein an exhaust gas line (5a, 5b) adjoins each outlet opening (4a, 4b), - at least two exhaust gas turbochargers (8, 9) are provided, each exhaust gas turbocharger (8, 9) comprising a turbine (8a, 9a), and the exhaust pipes (5a, 5b) of the at least two cylinders (3) are configured in such a way that the exhaust pipe (5a) of a switchable outlet opening (4a) of each cylinder (3) is formed into a first exhaust gas pipe (6a) 7a), which is connected to the turbine (8a) of a first exhaust gas turbocharger (8), and the exhaust pipes (5b) of the other outlet openings (4b) of the at least two cylinders (3) to form a second exhaust manifold (6b) to a second G 7), which is connected to the turbine (9a) of a second exhaust gas turbocharger (9), wherein - at least two cylinders (3) are configured in such a way that they form at least two cylinder groups, each with at least one cylinder (3) wherein the at least one cylinder (3) of a first cylinder group is a cylinder (3) which is also in operation when the internal combustion engine (1) is partially deactivated and the at least one cylinder (3) of a second cylinder group is designed as a load-dependent switchable cylinder (3), and - all outlet openings (4a) of the at least one cylinder (3) of the second cylinder group are designed as switchable outlet openings (4a).

Description

• – jeder Zylinder mindestens zwei Auslassöffnungen zum Abführen der Abgase aufweist, von denen mindestens eine als zuschaltbare Auslassöffnung ausgebildet ist, wobei sich an jede Auslassöffnung eine Abgasleitung zum Abführen der Abgase via Abgasabführsystem anschließt,
• – mindestens zwei Abgasturbolader vorgesehen sind, wobei jeder Abgasturbolader eine im Abgasabführsystem angeordnete Turbine umfasst, und
• – die Abgasleitungen der mindestens zwei Zylinder in der Art konfiguriert sind, dass die Abgasleitung einer zuschaltbaren Auslassöffnung jedes Zylinders unter Ausbildung eines ersten Abgaskrümmers in eine erste Gesamtabgasleitung mündet, welche mit der Turbine eines ersten Abgasturboladers verbunden ist, und die Abgasleitungen der anderen Auslassöffnungen der mindestens zwei Zylinder unter Ausbildung eines zweiten Abgaskrümmers zu einer zweiten Gesamtabgasleitung zusammenführen, welche mit der Turbine eines zweiten Abgasturboladers verbunden ist.

The invention relates to a supercharged internal combustion engine having at least one cylinder head with at least two cylinders, in which

• Each cylinder has at least two outlet openings for discharging the exhaust gases, of which at least one is designed as a switchable outlet opening, wherein an exhaust pipe for discharging the exhaust gases via exhaust gas discharge system adjoins each outlet opening,
• - At least two exhaust gas turbochargers are provided, each exhaust gas turbocharger comprises a turbine arranged in the Abgasabführsystem, and
• The exhaust pipes of the at least two cylinders are configured in such a way that the exhaust pipe of a switchable exhaust port of each cylinder opens into a first exhaust gas line, which is connected to the turbine of a first exhaust gas turbocharger, forming the first exhaust manifold, and the exhaust pipes of the other exhaust ports are at least two cylinders merge to form a second exhaust manifold to form a second exhaust manifold, which is connected to the turbine of a second exhaust gas turbocharger.

Furthermore, the invention relates to a method for operating such an internal combustion engine.

In the context of the present invention, the term internal combustion engine comprises gasoline engines, but also diesel engines and hybrid internal combustion engines, which use a hybrid combustion process, as well as hybrid drives, which in addition to the internal combustion engine comprise an electric machine 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.

Internal combustion engines have a cylinder block and at least one cylinder head, which are connected together to form the cylinder on a mounting end face. In order to control the charge cycle, an internal combustion engine requires control devices - usually in the form of globe valves - and actuators to operate these controls. The required for the movement of the valves valve actuating mechanism including the valves themselves is referred to as a valve train. Often, the cylinder head serves to accommodate the valve train.

As part of the change of charge, the exhaust of the combustion gases via the outlet openings of the cylinder and the filling with charge air via the inlet openings takes place. It is the task of the valve drive to enable or close the inlet and outlet openings in good time, with the aim of rapidly releasing as large flow cross sections as possible in order to keep the throttling losses in the inflowing and outflowing gas flows low, and to achieve as good a filling as possible effective, d. H. To ensure complete removal of the exhaust gases. Therefore, according to the prior art, the cylinders are often equipped with two or more inlet and outlet ports. Also, the at least two cylinders of the internal combustion engine, which is the subject of the present invention, are equipped with at least two outlet openings.

The exhaust pipes, which adjoin the outlet openings are at least partially integrated in the cylinder head according to the prior art. The exhaust pipes of the cylinders are usually combined to form a common exhaust gas line or - as in the internal combustion engine according to the invention - in groups to two or more total exhaust gas lines. The combination of exhaust pipes to an overall exhaust line is generally and in the context of the present invention referred to as exhaust manifold.

Downstream of the manifold, the exhaust gases are in this case supplied to the turbines of at least two exhaust gas turbochargers for charging the internal combustion engine. The advantages of an exhaust gas turbocharger, for example compared to a mechanical supercharger, are that there is no mechanical connection to the power transmission between the supercharger and the internal combustion engine. 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. However, an exhaust gas turbocharger disposed in the exhaust system leads to an increased exhaust back pressure upstream of the turbine, whereby the charge exchange can be adversely affected.

An exhaust gas turbocharger includes a compressor and a turbine disposed on the same shaft. The hot exhaust gas flow is fed to the turbocharger of the supercharger and relaxes with energy release in this turbine. This will set the shaft in rotation. 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 charging of the at least two cylinders is achieved. Optionally, a charge air cooling is provided, with which the compressed charge air is cooled before entering the cylinder.

The charge is used primarily to increase the performance of the internal combustion engine. 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. At the same vehicle boundary conditions, the load collective can thus be shifted to higher loads in which the specific fuel consumption is lower.

The design of the exhaust gas turbocharger often causes difficulties, 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 torque drop becomes understandable if it is taken into account that the boost pressure ratio depends on the turbine pressure ratio. For example, if the engine speed is reduced, this leads to a smaller exhaust gas mass flow and thus to a smaller turbine pressure ratio. As a result, at lower speeds, the boost pressure ratio also decreases, which is equivalent to a torque drop.

In principle, the drop in charge pressure could be counteracted by reducing the size of the turbine cross-section and the associated increase in the turbine pressure ratio. Thus, the torque drop is only shifted to lower speeds. In addition, this approach, d. H. the reduction of the turbine cross-section limits, since the desired charging and power increase even at high speeds, d. H. large amounts of exhaust gas, should be possible without restriction.

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. 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 conducted past the turbine by means of a bypass line as part of the so-called exhaust gas blow-off. This approach has the disadvantage that the charging behavior at higher speeds or larger amounts of exhaust gas is insufficient.

The torque characteristic of a supercharged internal combustion engine may be further characterized by a plurality of turbochargers arranged in parallel, i. H. be improved by a plurality of parallel turbines with a smaller turbine cross-section, with successively increasing speed or increasing amount of exhaust gas according to the so-called register turbines are switched on successively.

A supercharged internal combustion engine with at least two turbines arranged in parallel is also an object of the present invention. A turbine, namely the turbine of a first exhaust gas turbocharger, is designed as a switchable turbine, which can be acted upon at higher speeds or larger amounts of exhaust gas, d. H. can be activated.

To disable or enable this first switchable turbine, d. H. To be able to switch, a switching device must be provided. In the present case, the valve drive assumes the function of a switching device. According to the invention, for this purpose, each cylinder is equipped with at least two outlet openings, of which at least one is designed as a switchable outlet opening. The exhaust gas lines of the cylinders are configured in such a way that the exhaust pipe of a switchable outlet opening of each cylinder opens into a first exhaust gas line, which is connected to the turbine of the first exhaust gas turbocharger, forming the first exhaust gas manifold, and the exhaust pipes of the other outlet openings of the cylinders are formed a second exhaust manifold merge to form a second exhaust line, which is connected to the turbine of a second exhaust gas turbocharger.

Switching off the switchable outlet openings, whose exhaust lines merge to form the first exhaust manifold to the first overall exhaust line, cuts off the turbine of the first exhaust gas turbocharger from the exhaust gas supply, whereby this turbine is turned off. Only with larger amounts of exhaust gas or higher speeds, the switchable outlet openings are opened as part of the change of charge, thereby activating the switchable turbine, d. H. Exhaust gas is applied.

Thus, the torque characteristic of the internal combustion engine can be significantly improved, in particular the torque at low speeds, d. H. Small amounts of exhaust gas are noticeably raised.

The fact that the switching device according to the invention is formed by the valve train and is not arranged in Abgasabführsystem or in the first turbine itself, has the significant advantage that this switching device - the respective exhaust valve excluded - is not highly stressed thermally. A malfunction or leakage of the switching device is therefore not to be feared. The life expectancy of the switching device increases. In addition, a valve drive for carrying out the charge exchange already exists, so that no additional switching device must be provided. The existing valve train must only be made switchable or variable.

In view of the foregoing, it is an object of the present invention to provide a supercharged internal combustion engine according to the preamble of claim 1 which is improved in performance.

A further sub-task of the present invention is to show a method for operating such an internal combustion engine.

• – jeder Zylinder mindestens zwei Auslassöffnungen zum Abführen der Abgase aufweist, von denen mindestens eine als zuschaltbare Auslassöffnung ausgebildet ist, wobei sich an jede Auslassöffnung eine Abgasleitung zum Abführen der Abgase via Abgasabführsystem anschließt,
• – mindestens zwei Abgasturbolader vorgesehen sind, wobei jeder Abgasturbolader eine im Abgasabführsystem angeordnete Turbine umfasst, und
• – die Abgasleitungen der mindestens zwei Zylinder in der Art konfiguriert sind, dass die Abgasleitung einer zuschaltbaren Auslassöffnung jedes Zylinders unter Ausbildung eines ersten Abgaskrümmers in eine erste Gesamtabgasleitung mündet, welche mit der Turbine eines ersten Abgasturboladers verbunden ist, und die Abgasleitungen der anderen Auslassöffnungen der mindestens zwei Zylinder unter Ausbildung eines zweiten Abgaskrümmers zu einer zweiten Gesamtabgasleitung zusammenführen, welche mit der Turbine eines zweiten Abgasturboladers verbunden ist, und die dadurch gekennzeichnet ist, dass
• – mindestens zwei Zylinder in der Art konfiguriert sind, dass diese mindestens zwei Zylindergruppen mit jeweils mindestens einem Zylinder bilden, wobei der mindestens eine Zylinder einer ersten Zylindergruppe ein auch bei Teilabschaltung der Brennkraftmaschine in Betrieb befindlicher Zylinder ist und der mindestens eine Zylinder einer zweiten Zylindergruppe als lastabhängig schaltbarer Zylinder ausgebildet ist, und
• – sämtliche Auslassöffnungen des mindestens einen Zylinders der zweiten Zylindergruppe als zuschaltbare Auslassöffnungen ausgebildet sind.

The first sub-task is solved by a supercharged internal combustion engine having at least one cylinder head with at least two cylinders, in which

• Each cylinder has at least two outlet openings for discharging the exhaust gases, of which at least one is designed as a switchable outlet opening, wherein an exhaust pipe for discharging the exhaust gases via exhaust gas discharge system adjoins each outlet opening,
• - At least two exhaust gas turbochargers are provided, each exhaust gas turbocharger comprises a turbine arranged in the Abgasabführsystem, and
• The exhaust pipes of the at least two cylinders are configured in such a way that the exhaust pipe of a switchable exhaust port of each cylinder opens into a first exhaust gas line, which is connected to the turbine of a first exhaust gas turbocharger, forming the first exhaust manifold, and the exhaust pipes of the other exhaust ports are at least two cylinders merge to form a second exhaust manifold to form a second exhaust manifold, which is connected to the turbine of a second exhaust gas turbocharger, and which is characterized in that
• - At least two cylinders are configured in such a way that they form at least two cylinder groups, each having at least one cylinder, wherein the at least one cylinder of a first cylinder group is also in partial shutdown of the internal combustion engine in operation cylinder and the at least one cylinder of a second cylinder group as load-dependent switchable cylinder is formed, and
• - All outlet openings of the at least one cylinder of the second cylinder group are formed as switchable outlet openings.

The internal combustion engine according to the invention not only has turbines arranged in parallel, which noticeably improve the torque supply, in particular in the lower rpm range, by successive shifting, but moreover also via a so-called partial deactivation.

A solution to increase the efficiency, d. H. to reduce fuel consumption, the cylinder deactivation, d. H. the shutdown of individual cylinders in certain load ranges.

The efficiency of a gasoline engine in partial load operation can be improved by such a partial shutdown, d. H. be increased, because the shutdown of a cylinder of a multi-cylinder internal combustion engine increases the load of the remaining still in operation cylinder at constant engine power, so that the throttle for introducing a larger air mass in these cylinders can be opened or must, resulting in a total Entdrosselung the internal combustion engine is achieved. The continuously operating cylinders operate during partial shutdown in the area of higher loads, where the specific fuel consumption is lower. The load collective is shifted to higher loads.

The further operated during the partial shutdown cylinder also have due to the larger air mass supplied or mixture mass improved mixture formation and tolerate higher exhaust gas recirculation rates.

Further efficiency advantages result from the fact that a deactivated cylinder as a result of the lack of combustion no wall heat losses generated as a result of heat transfer from the combustion gases to the combustion chamber walls.

Although diesel engines, d. H. self-igniting internal combustion engines, due to the applied quality control higher efficiency, d. H. have a lower fuel consumption than gasoline engines, in which the load is set by throttling or quantity control on the filling of the cylinder, there is room for improvement in diesel engines and improvement in fuel consumption and efficiency.

A concept for reducing fuel consumption is also the case with diesel engines Cylinder shutdown, ie the shutdown of individual cylinders in certain load ranges. The efficiency of the diesel engine in part-load operation can be improved by a partial shutdown, ie increased, because the shutdown of at least one cylinder of a multi-cylinder internal combustion engine increases at constant engine power even in the diesel engine, the load of the remaining still in operation cylinder, so that these cylinders in areas higher Working loads where the specific fuel consumption is lower. The load collective in part-load operation of the diesel engine is shifted to higher loads.

With regard to the wall heat losses, the same advantages result as in the gasoline engine, for which reason reference is made to the corresponding explanations.

The partial shutdown in diesel engines should also prevent the fuel-air mixture under the quality scheme with decreasing load by reducing the amount of fuel used too much.

To realize a partial shutdown, the at least two cylinders of the internal combustion engine according to the invention are configured in such a way that they form at least two cylinder groups, each with at least one cylinder. The at least one cylinder of a first cylinder group is a cylinder which is also in operation when the internal combustion engine is partially switched off, and the at least one cylinder of a second cylinder group is designed as a load-dependent switchable cylinder.

In addition, all the outlet openings of the at least one cylinder of the second cylinder group are designed as switchable outlet openings, so that the second cylinder group can be completely separated from the exhaust-gas removal system during partial shut-off, i. H. does not feed into the exhaust system.

The internal combustion engine according to the invention allows in addition to the operating mode of the partial shutdown a second operating mode in which the turbine of the second exhaust gas turbocharger is acted upon by the at least two cylinders of the internal combustion engine with exhaust and the turbine of the first exhaust gas turbocharger is deactivated, including the switchable outlet openings of the cylinder whose exhaust pipes in the first exhaust gas line open, be deactivated. In a third operating mode then both turbines of the at least two exhaust gas turbochargers are acted upon by the cylinders of the internal combustion engine with exhaust gas. For this purpose, all switchable outlet openings are activated and actuated.

The internal combustion engine according to the invention thus enables both the improvement of the torque characteristic, in particular at low speeds, as well as a higher efficiency, d. H. a lower fuel consumption.

The internal combustion engine according to the invention solves the first object underlying the invention, namely to provide a supercharged internal combustion engine which is improved in terms of its operating behavior.

Further advantageous embodiments of the internal combustion engine according to the invention are discussed in connection with the subclaims.

Embodiments of the internal combustion engine in which the at least one cylinder of the first cylinder group has only one connectable outlet opening, the exhaust line of which opens into the first overall exhaust gas line, are advantageous. This embodiment satisfies the minimum requirements to be imposed on the first cylinder group and its outlet ports to shut off the first turbine. For this purpose, namely, the cylinders of the first cylinder group must have at least one switchable outlet opening, which is or must be the outlet openings whose exhaust gas lines open into the first overall exhaust gas line.

Embodiments of the internal combustion engine in which all outlet openings of the at least one cylinder of the first cylinder group are designed as switchable outlet openings are also advantageous. This embodiment takes into account the fact that the cylinders of the first cylinder group can also be equipped exclusively with switchable outlet openings and this in particular does not preclude the application of the method according to the invention, even if this feature exceeds the minimum requirements.

Embodiments of the internal combustion engine in which the exhaust pipes of the at least two cylinders merge within the cylinder head to form total exhaust gas lines are advantageous.

The Integration of the exhaust manifolds into the cylinder head reduces the mass and length of the exhaust evacuation systems from the exhaust ports to the turbines and exhaust after-treatment systems. As a result, the exhaust enthalpy of the hot exhaust gases can be optimally utilized and ensure a quick response of the turbocharger. In addition, downstream exhaust aftertreatment systems rapidly reach their operating temperature or light-off temperature, in particular after a cold start of the internal combustion engine. The integration of the exhaust manifold in the cylinder head also allows the densest possible packaging of the drive unit. Optionally, it can be attended to provided in the cylinder head liquid cooling, in such a way that the manifold does not have to be made of high temperature resistant materials.

In a supercharged internal combustion engine having at least two cylinders arranged in series along a longitudinal axis of the cylinder head, in which the at least one cylinder head can be connected to a cylinder block at a mounting end face, embodiments are advantageous, which are characterized in that an overall exhaust gas line on that of the assembly Front side facing away from another total exhaust line is arranged.

According to the above embodiment, the two exhaust manifolds are at least partially superimposed, d. H. in the direction of a cylinder longitudinal axis spaced from one another, because the one exhaust line is arranged on the side facing away from the mounting end side of the other total exhaust line.

If the at least two cylinders are arranged in series along a longitudinal axis of the cylinder head, embodiments of the internal combustion engine are advantageous in which the at least two total exhaust gas lines are offset along the longitudinal axis of the cylinder head to form a distance.

In the present case, the total exhaust gas lines are arranged offset along the longitudinal axis of the cylinder head to form a distance Δ. The offset allows a compact design of the cylinder head and at the same time ensures a sufficiently large distance of the total exhaust gas lines from each other. In this way, despite a compact design enough space between the exhaust pipes remains compared to embodiments in which the total exhaust pipes along the cylinder head longitudinal axis have no offset. This also facilitates the arrangement of coolant channels in the cylinder head between the two exhaust pipes, if a liquid cooling is to be provided.

In a supercharged internal combustion engine having at least four cylinders arranged in series along a longitudinal axis of the cylinder head, embodiments are advantageous which are characterized in that the outer cylinders form a cylinder group and the at least two inner cylinders form a different cylinder group.

Embodiments of the internal combustion engine in which the overall exhaust gas lines merge downstream of the turbines to form a common exhaust gas line are advantageous.

Then, a common exhaust aftertreatment of the entire exhaust gas of the at least two cylinders take place, namely with an arranged in the common exhaust pipe exhaust aftertreatment system. These may be, for example, a particulate filter, an oxidation catalyst and / or an exhaust aftertreatment system for reducing nitrogen oxides.

Alternatively or additionally, an exhaust aftertreatment system may also be provided in each overall exhaust line, possibly also a plurality of exhaust aftertreatment systems.

This allows a closer engine arrangement of the exhaust aftertreatment systems, d. H. close to the outlet openings of the cylinders. This embodiment also takes into account the fact that the proposed turbines are partly operated at different operating points. Thus, the load-dependent switchable cylinder are usually only at higher loads, in which the exhaust gas has a high or higher temperature switched on, whereas the cylinder also in partial shutdown of the engine in operation are also exposed to exhaust gas of the partial load operation, which is a lower Temperature has. Different exhaust gas temperatures may require different exhaust aftertreatment systems.

Embodiments of the internal combustion engine in which at least one exhaust aftertreatment system is arranged downstream of the turbine in each overall exhaust gas line are therefore also advantageous.

Embodiments of the internal combustion engine in which at least one turbine is designed as a waste-gate turbine are advantageous, wherein upstream of this turbine a bypass line branches off from the exhaust-gas removal system and a shut-off element is provided in the bypass line.

Also advantageous are embodiments of the internal combustion engine, in which at least one turbine has a variable turbine geometry, which allows a high degree of adaptation to the respective operating point by adjusting the turbine geometry or the effective turbine cross section. In this case, upstream of the impeller of the turbine vanes for influencing the flow direction are arranged. In contrast to the blades of the rotating impeller, the vanes do not rotate with the shaft of the turbine, ie the impeller. The vanes are stationary arranged, but not completely immobile, but rotatable about its axis, so that the flow of the blades can be influenced.

On the other hand, if a turbine has a fixed invariable geometry, the vanes are not only stationary but also completely immovable, i. H. rigidly fixed.

Embodiments of the internal combustion engine in which the turbine of the second exhaust gas turbocharger is dimensioned larger than the turbine of the first exhaust gas turbocharger are advantageous. This embodiment extends the map range of the internal combustion engine in which the second mode of operation is applicable to higher speeds.

The cylinder head of a supercharged internal combustion engine is basically a thermally and mechanically highly loaded component. In particular, in the integration of the exhaust manifold, the thermal load of the internal combustion engine or the cylinder head increases again, so that increased demands are placed on the cooling.

Therefore, embodiments of the supercharged internal combustion engine in which liquid cooling is provided are advantageous.

Embodiments of the supercharged internal combustion engine in which the at least one cylinder head is equipped with at least one integrated coolant jacket are advantageous. The cylinder block which can be connected to the at least one cylinder head can likewise be equipped with at least one integrated coolant jacket.

Embodiments of the supercharged internal combustion engine in which the at least one coolant jacket also extends between the overall exhaust gas lines are advantageous.

The second sub-task on which the invention is based, namely to disclose a method for operating an internal combustion engine of the type described above, is achieved by a method in which the switchable outlet openings of the at least two cylinders are switched as a function of the load T and the engine speed n _mot .

The comments made in connection with the internal combustion engine according to the invention also apply to the inventive method.

The load and / or the speed need not be constants, but may rather be functions of other operating parameters, such as the exhaust gas temperature, the cylinder head temperature and / or the coolant temperature. In particular, the speed at which switching is made by the load and the load at which it is switched may be dependent on the speed.

• – der mindestens eine Zylinder der zweiten Zylindergruppe abgeschaltet wird,
• – der mindestens eine Zylinder der zweiten Zylindergruppe durch Abschalten der Auslassöffnungen deaktiviert wird, und
• – die Turbinen der mindestens zwei Abgasturbolader von dem mindestens einen Zylinder der ersten Zylindergruppe mit Abgas versorgt werden, indem zu den Auslassöffnungen des mindestens einen Zylinders der ersten Zylindergruppe gehörende Ventile betätigt werden.

Embodiments of the method are advantageous in which, in a first operating mode

• - the at least one cylinder of the second cylinder group is turned off,
• - The at least one cylinder of the second cylinder group is deactivated by switching off the outlet openings, and
• - The turbines of the at least two exhaust gas turbocharger are supplied from the at least one cylinder of the first cylinder group with exhaust gas by operated to the outlet openings of the at least one cylinder of the first cylinder group associated valves.

The first operating mode relates to the partial shutdown during which the cylinders of the second cylinder group are switched off. According to the invention, the at least one cylinder of the first cylinder group then supplies not only a turbine with exhaust gas, but rather all or both turbines. As a result, the exhaust gas back pressure in the exhaust gas removal system can be reduced, the charge cycle of the first cylinder group during partial shutdown can be improved, and thus the efficiency can be further increased.

• – die zuschaltbare Auslassöffnung des mindestens einen Zylinders der ersten Zylindergruppe, deren Abgasleitung in die erste Gesamtabgasleitung mündet, deaktiviert wird und die zuschaltbare Auslassöffnung des mindestens einen Zylinders der zweiten Zylindergruppe, deren Abgasleitung in die zweite Gesamtabgasleitung mündet, aktiviert wird, falls die Last eine vorgebbare Last übersteigt und die Drehzahl kleiner ist als eine vorgebbare Drehzahl, wodurch die Brennkraftmaschine in einen zweiten Betriebsmodus überführt wird, in welchem die Turbine des zweiten Abgasturboladers von den mindestens zwei Zylindern der Brennkraftmaschine mit Abgas beaufschlagt wird und die Turbine des ersten Abgasturboladers deaktiviert ist, oder
• – die zuschaltbaren Auslassöffnungen des mindestens einen Zylinders der zweiten Zylindergruppe aktiviert werden, falls die Last eine vorgebbare Last übersteigt und die Drehzahl größer ist als die vorgebbare Drehzahl, wodurch die Brennkraftmaschine in einen dritten Betriebsmodus überführt wird, in welchem die Turbinen der mindestens zwei Abgasturbolader von den mindestens zwei Zylindern der Brennkraftmaschine mit Abgas beaufschlagt werden.

In this context, embodiments of the method are advantageous in which, starting from the first operating mode, the at least one deactivated cylinder of the second cylinder group is switched on, wherein

• - The switchable outlet opening of the at least one cylinder of the first cylinder group, the exhaust pipe opens into the first exhaust line, is deactivated and the switchable outlet of the at least one cylinder of the second cylinder group, the exhaust pipe opens into the second total exhaust line is activated, if the load is a predetermined Load exceeds and the speed is less than a predetermined speed, whereby the internal combustion engine is converted into a second operating mode in which the turbine of the second exhaust gas turbocharger is acted upon by the at least two cylinders of the internal combustion engine with exhaust gas and the turbine of the first exhaust gas turbocharger is deactivated, or
• - The switchable outlet openings of the at least one cylinder of the second cylinder group are activated if the load exceeds a predetermined load and the speed is greater than the predetermined speed, whereby the internal combustion engine is transferred to a third operating mode, in which the turbines of the at least two exhaust gas turbocharger The at least two cylinders of the internal combustion engine are subjected to exhaust gas.

• – die zuschaltbare Auslassöffnung des mindestens einen Zylinders der ersten Zylindergruppe, deren Abgasleitung in die erste Gesamtabgasleitung mündet, aktiviert wird und die zuschaltbare Auslassöffnung des mindestens einen Zylinders der zweiten Zylindergruppe, deren Abgasleitung in die erste Gesamtabgasleitung mündet, aktiviert wird, falls die Drehzahl eine vorgebbare Drehzahl übersteigt, wodurch die Brennkraftmaschine in den dritten Betriebsmodus überführt wird.

Advantageous embodiments of the method are those in which, starting from the second operating mode,

• - The switchable outlet opening of the at least one cylinder of the first cylinder group, the exhaust pipe opens into the first exhaust line, is activated and the switchable outlet of the at least one cylinder of the second cylinder group, the exhaust pipe opens into the first exhaust line, if the speed is a predetermined Speed exceeds, whereby the internal combustion engine is transferred to the third operating mode.

• – die zuschaltbare Auslassöffnung des mindestens einen Zylinders der ersten Zylindergruppe, deren Abgasleitung in die erste Gesamtabgasleitung mündet, deaktiviert wird und die zuschaltbare Auslassöffnung des mindestens einen Zylinders der zweiten Zylindergruppe, deren Abgasleitung in die erste Gesamtabgasleitung mündet, deaktiviert wird, falls die Drehzahl eine vorgebbare Drehzahl unterschreitet, wodurch die Brennkraftmaschine in den zweiten Betriebsmodus überführt wird.

Also advantageous are embodiments of the method in which, starting from the third operating mode,

• - The switchable outlet opening of the at least one cylinder of the first cylinder group, the exhaust pipe opens into the first exhaust line, is deactivated and the switchable outlet of the at least one cylinder of the second cylinder group, the exhaust pipe opens into the first exhaust line, if the speed is a predetermined Speed falls below, whereby the internal combustion engine is transferred to the second operating mode.

• – ausgehend vom zweiten Betriebsmodus die zuschaltbare Auslassöffnung des mindestens einen Zylinders der ersten Zylindergruppe, deren Abgasleitung in die erste Gesamtabgasleitung mündet, aktiviert wird und die zuschaltbare Auslassöffnung des mindestens einen Zylinders der zweiten Zylindergruppe, deren Abgasleitung in die zweite Gesamtabgasleitung mündet, deaktiviert wird, oder
• – ausgehend vom dritten Betriebsmodus die zuschaltbaren Auslassöffnungen des mindestens einen Zylinders der zweiten Zylindergruppe deaktiviert werden.

In this context, embodiments of the method are advantageous in which the internal combustion engine is converted into the first operating mode if the load falls below a predefinable load, wherein

• Starting the second operating mode, the switchable outlet opening of the at least one cylinder of the first cylinder group, the exhaust pipe opens into the first exhaust line, is activated and the switchable outlet of the at least one cylinder of the second cylinder group, the exhaust pipe opens into the second total exhaust line, or
• - Starting the third operating mode, the switchable outlet openings of the at least one cylinder of the second cylinder group are deactivated.

The amount of exhaust gas correlates with an uncharged internal combustion engine approximately with the speed and / or the load of the internal combustion engine and that depends on the load control used in the individual case. In the case of a quantity control, the exhaust gas quantity also increases at constant speed with increasing load, whereas the exhaust gas quantity in the case of traditional quality controlled diesel engines is only speed-dependent, because with load change and constant speed the mixture composition varies, but not the mixture quantity. The internal combustion engine according to the invention is a supercharged internal combustion engine, so that in addition the charge pressure on the intake side has to be considered.

Although reference is made in the context of the method according to the invention to the load and the rotational speed, it would also be possible to focus on the load and the exhaust gas quantity and not on the rotational speed.

In the following the invention is based on an embodiment according to the 1 and 2 described in more detail. Hereby shows:

1 schematically a first embodiment of the internal combustion engine, and

2 schematically the map of the first embodiment of the internal combustion engine.

1 schematically shows a first embodiment of the supercharged internal combustion engine 1 that with two exhaust gas turbochargers 8th . 9 Is provided. Every turbocharger 8th . 9 includes a turbine 8a . 9a and a compressor 8b . 9b , The hot exhaust gas relaxes in the turbines 8a . 9a under energy release. The compressors 8b . 9b compress the charge air via intake pipes 11a . 11b , Intercooler 10 and plenum 12 the cylinders 3 is supplied, whereby a charge of the internal combustion engine 1 is reached.

It is a four-cylinder in-line engine 1 in which the four cylinders 3 along the longitudinal axis of the cylinder head 2 , ie arranged in series. The four cylinders 3 are configured and form two cylinder groups with two cylinders each 3 , where the two inner cylinders 3 form a second cylinder group whose cylinder 3 as a load-dependent switchable cylinder 3 are formed, which are turned off in the context of a partial shutdown, and the two outer cylinder 3 form a first cylinder group whose cylinder 3 are also in partial shutdown in operation.

Every cylinder 3 has two outlet openings 4a . 4b to which are exhaust pipes 5a . 5b for discharging the exhaust gases via Abgasabführsystem connect, with all outlet openings 4a the two inner cylinders 3 ie the outlet openings 4a the second cylinder group, as switchable outlet openings 4a are formed and the two outer cylinder 3 ie the first cylinder group, in each case only one connectable outlet opening 4a exhibit.

The exhaust pipes 5a . 5b the four cylinders 3 are configured in the way that the exhaust pipe 5a a switchable outlet opening 4a every cylinder 3 under training of a first exhaust manifold 6a in a first total exhaust line 7a which ends with the turbine 8a of the first exhaust gas turbocharger 8th connected, and the exhaust pipes 5a . 5b the other outlet openings 4a . 4b the four cylinders 3 under formation of a second exhaust manifold 6b to a second total exhaust line 7b merge, which with the turbine 9a the second exhaust gas turbocharger 9 connected is.

The exhaust pipes 5a . 5b the cylinder 3 lead under training of two in the cylinder head 2 integrated exhaust manifolds 6a . 6b to two total exhaust pipes 7a . 7b together. These total exhaust pipes 7a . 7b in turn lead to a common exhaust pipe 14 together.

Downstream of each turbine 8a . 9a each is an exhaust aftertreatment system 13a . 13b intended. The exhaust aftertreatment systems 13a . 13b may have differences in structure and thus take into account the fact that the proposed turbines 8a . 9a at least temporarily operated at different boundary conditions and the state variables of the turbine-related exhaust gas flow, namely pressure and temperature, can differ greatly.

In the present case lead the two total intake lines 11a . 11b downstream of the compressor 8b . 9b together, with the first compressor 8b , Especially in a second operating mode B, can be separated from the rest of the intake system, so that the second compressor 9b not in the first compressor 8b into it. This is downstream of the first compressor 8b a shut-off arranged, the deactivation of this compressor 8b serves. So that the first compressor 8b does not have to promote against the resistance of the closed shut-off, a bypass line is provided, in which also a shut-off is arranged.

The second turbine 9a is designed as a waste-gate turbine, whose bypass line upstream of the turbine 9a from the second total exhaust line 7b branches off and downstream of the turbine 9a and upstream of the exhaust aftertreatment system 13b again in this total exhaust line 7b empties.

The illustrated internal combustion engine 1 allows a first operating mode A, which relates to the partial shutdown. During partial shutdown, the two internal cylinders 3 the second cylinder group switched off and the associated outlet openings 4a also. Then supply the two outer cylinder 3 the first cylinder group both turbines 8a . 9a with exhaust gas, whereby the exhaust back pressure is lowered in the Abgasabführsystem and the charge cycle of the first cylinder group is improved during partial shutdown. The efficiency increases again.

According to a second operating mode B, the turbine 9a the second exhaust gas turbocharger 9 from the four cylinders 3 the internal combustion engine 1 Exhaust gas is applied and the turbine 8a of the first exhaust gas turbocharger 8th is disabled, including the switchable outlet openings 4a the cylinder 3 , their exhaust pipes 4a into the first total exhaust gas line 7a to be deactivated.

In a third operating mode C then both turbines 8a . 9a from the four cylinders 3 the internal combustion engine 1 Exhaust gas is applied. For this purpose, all switchable outlet openings 4a activated and operated.

2 schematically shows the map of the first embodiment of the internal combustion engine with the three different operating modes A, B, C, wherein the abscissa, the speed n _mot and the ordinate, the load T is plotted.

It can be seen that the speed n _mot at which switching is dependent on the load T and the load T at which switching is dependent on the speed n _mot .

LIST OF REFERENCE NUMBERS

1

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

2

 cylinder head

3

 cylinder

4a

 switchable outlet opening

4b

 outlet

5a

 Exhaust pipe of a switchable outlet opening

5b

 exhaust pipe

6a

 first exhaust manifold

6b

 second exhaust manifold

7a

 first total exhaust gas line

7b

 second total exhaust line

8th

 first exhaust gas turbocharger

8a

 first turbine, switchable turbine

8b

 first compressor

9

 second exhaust gas turbocharger

9a

 second turbine

9b

 second compressor

10

 Intercooler

11a

 first suction line

11b

 second intake pipe

12

 plenum

13a

 aftertreatment system

13b

 aftertreatment system

14

 common exhaust pipe

A

 first operating mode

B

 second operating mode

C

 third operating mode

T

 Torque, load

n _mot

 Speed of the internal combustion engine

Claims (18)

Charged internal combustion engine ( 1 ) with at least one cylinder head ( 2 ) with at least two cylinders ( 3 ), in which - each cylinder ( 3 ) at least two outlet openings ( 4a . 4b ) for discharging the exhaust gases, of which at least one as switchable outlet ( 4a ) is formed, wherein at each outlet opening ( 4a . 4b ) an exhaust pipe ( 5a . 5b ) for discharging the exhaust gases via Abgasabführsystem connects, - at least two exhaust gas turbochargers ( 8th . 9 ) are provided, each exhaust gas turbocharger ( 8th . 9 ) a turbine arranged in the exhaust-gas removal system ( 8a . 9a ), and - the exhaust pipes ( 5a . 5b ) the at least two cylinders ( 3 ) are configured in such a way that the exhaust pipe ( 5a ) a switchable outlet opening ( 4a ) of each cylinder ( 3 ) to form a first exhaust manifold ( 6a ) into a first overall exhaust gas line ( 7a ), which with the turbine ( 8a ) of a first exhaust gas turbocharger ( 8th ), and the exhaust pipes ( 5a . 5b ) of the other outlet openings ( 4a . 4b ) the at least two cylinders ( 3 ) to form a second exhaust manifold ( 6b ) to a second total exhaust line ( 7b ), which with the turbine ( 9a ) of a second exhaust gas turbocharger ( 9 ), characterized in that - at least two cylinders ( 3 ) are configured in such a way that they have at least two cylinder groups each having at least one cylinder ( 3 ), wherein the at least one cylinder ( 3 ) a first cylinder group also at partial shutdown of the internal combustion engine ( 1 ) operating cylinder ( 3 ) and the at least one cylinder ( 3 ) a second cylinder group as a load-dependent switchable cylinder ( 3 ), and - all the outlet openings ( 4a ) of the at least one cylinder ( 3 ) of the second cylinder group as switchable outlet openings ( 4a ) are formed. Charged internal combustion engine ( 1 ) according to claim 1, characterized in that the at least one cylinder ( 3 ) of the first cylinder group only one switchable outlet opening ( 4a ), whose exhaust pipe ( 5a ) into the first exhaust line ( 7a ) opens. Charged internal combustion engine ( 1 ) according to claim 1, characterized in that all the outlet openings ( 4a ) of the at least one cylinder ( 3 ) of the first cylinder group as switchable outlet openings ( 4a ) are formed. Charged internal combustion engine ( 1 ) according to one of the preceding claims, characterized in that the exhaust pipes ( 5a . 5b ) the at least two cylinders ( 3 ) within the cylinder head ( 2 ) to total exhaust gas lines ( 7a . 7b ) merge. Charged internal combustion engine ( 1 ) according to one of the preceding claims with at least two along a longitudinal axis of the cylinder head ( 2 ) arranged in series cylinders ( 3 ), wherein the at least one cylinder head ( 2 ) is connectable to a cylinder block at a mounting end face, characterized in that an overall exhaust gas line ( 7a . 7b ) on the side facing away from the mounting end side of another total exhaust line ( 7a . 7b ) is arranged. Charged internal combustion engine ( 1 ) according to claim 5, characterized in that the at least two total exhaust gas lines ( 7a . 7b ) along the longitudinal axis of the cylinder head ( 2 ) are arranged offset to form a distance. Charged internal combustion engine ( 1 ) according to one of the preceding claims with at least four along a longitudinal axis of the cylinder head ( 2 ) arranged in series cylinders ( 3 ), characterized in that the outer cylinders ( 3 ) form a cylinder group and the at least two inner cylinders ( 3 ) form another cylinder group. Charged internal combustion engine ( 1 ) according to one of the preceding claims, characterized in that the total exhaust gas lines ( 7a . 7b ) downstream of the turbines ( 8a . 9a ) to a common exhaust pipe ( 14 ) merge. Charged internal combustion engine ( 1 ) according to one of the preceding claims, characterized in that in each total exhaust line ( 7a . 7b ) at least one exhaust aftertreatment system ( 13a . 13b ) downstream of the turbine ( 8a . 9a ) is arranged. Charged internal combustion engine ( 1 ) according to one of the preceding claims, characterized in that at least one turbine ( 8a . 9a ) is designed as a waste gate turbine, wherein upstream of this turbine ( 8a . 9a ) branches off a bypass line from Abgasabführsystem and a shut-off element is provided in the bypass line. Charged internal combustion engine ( 1 ) according to one of the preceding claims, characterized in that at least one turbine ( 8a . 9a ) has a variable turbine geometry. Charged internal combustion engine ( 1 ) according to one of the preceding claims, characterized in that the turbine ( 9a ) of the second exhaust gas turbocharger ( 9 ) is larger than the turbine ( 8a ) of the first exhaust gas turbocharger ( 8th ). Method for operating a supercharged internal combustion engine ( 1 ) according to one of the preceding claims, characterized in that the switchable outlet openings ( 4a ) the at least two cylinders ( 3 ) are switched in dependence on the load T and the speed n _mot . A method according to claim 13, characterized in that in a first operating mode - the at least one cylinder ( 3 ) of the second cylinder group is switched off, - the at least one cylinder ( 3 ) of the second cylinder group by switching off the outlet openings ( 4a ), and - the turbines ( 8a . 9a ) of the at least two turbocharger ( 8th . 9 ) of the at least one cylinder ( 3 ) of the first cylinder group are supplied with exhaust gas by passing to the outlet openings ( 4a . 4b ) of the at least one cylinder ( 3 ) of the first cylinder group belonging valves are actuated. A method according to claim 14, characterized in that starting from the first operating mode, the at least one deactivated cylinder ( 3 ) is connected to the second cylinder group, wherein - the switchable outlet opening ( 4a ) of the at least one cylinder ( 3 ) of the first cylinder group, the exhaust pipe ( 5a ) into the first exhaust line ( 7a ), is deactivated and the switchable outlet opening ( 4a ) of the at least one cylinder ( 3 ) of the second cylinder group whose exhaust pipe ( 5a ) into the second total exhaust line ( 7b ) is activated, if the load exceeds a predetermined load and the speed is less than a predetermined speed, whereby the internal combustion engine ( 1 ) is transferred to a second operating mode, in which the turbine ( 9a ) of the second exhaust gas turbocharger ( 9 ) of the at least two cylinders ( 3 ) of the internal combustion engine ( 1 ) is exposed to exhaust gas and the turbine ( 8a ) of the first exhaust gas turbocharger ( 8th ) is deactivated, or - the switchable outlet openings ( 4a ) of the at least one cylinder ( 3 ) of the second cylinder group are activated if the load exceeds a predefinable load and the speed is greater than the predetermined speed, whereby the internal combustion engine ( 1 ) is transferred to a third operating mode in which the turbines ( 8a . 9a ) of the at least two turbocharger ( 8th . 9 ) of the at least two cylinders ( 3 ) of the internal combustion engine ( 1 ) are exposed to exhaust gas. Method according to claim 15, characterized in that, starting from the second operating mode, - the connectable outlet opening ( 4a ) of the at least one cylinder ( 3 ) of the first cylinder group, the exhaust pipe ( 5a ) into the first exhaust line ( 7a ), is activated and the switchable outlet opening ( 4a ) of the at least one cylinder ( 3 ) of the second cylinder group whose exhaust pipe ( 5a ) into the first exhaust line ( 7a ) is activated, if the speed exceeds a predetermined speed, whereby the internal combustion engine ( 1 ) is transferred to the third operating mode. A method according to claim 15, characterized in that starting from the third operating mode, - the switchable outlet opening ( 4a ) of the at least one cylinder ( 3 ) of the first cylinder group, the exhaust pipe ( 5a ) into the first exhaust line ( 7a ), is deactivated and the switchable outlet opening ( 4a ) of the at least one cylinder ( 3 ) of the second cylinder group whose exhaust pipe ( 5a ) into the first exhaust line ( 7a ), is deactivated, if the speed falls below a predetermined speed, whereby the internal combustion engine ( 1 ) is transferred to the second operating mode. Method according to one of claims 15 to 17, characterized in that the internal combustion engine ( 1 ) is transferred into the first operating mode, if the load falls below a predeterminable load, wherein - starting from the second operating mode, the switchable outlet opening ( 4a ) of the at least one cylinder ( 3 ) of the first cylinder group, the exhaust pipe ( 5a ) into the first exhaust line ( 7a ), is activated and the switchable outlet opening ( 4a ) of the at least one cylinder ( 3 ) of the second cylinder group whose exhaust pipe ( 5a ) into the second total exhaust line ( 7b ), is deactivated, or - starting from the third operating mode the switchable outlet openings ( 4a ) of the at least one cylinder ( 3 ) of the second cylinder group are deactivated.

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