DE202015103551U1 - Exhaust turbo-charged internal combustion engine with partial shutdown and additional compressor - Google Patents

Abstract

A supercharged internal combustion engine (10) having at least one cylinder head comprising at least three cylinders (1, 2, 3, 4), in which - each cylinder (1, 2, 3, 4) has at least one inlet opening to which a suction line for supplying Charge air via the intake system (5) connects, - each cylinder (1, 2, 3, 4) has at least one outlet opening to which an exhaust pipe for discharging the exhaust gases via Abgasabführsystem (6) connects, - at least one exhaust gas turbocharger (7) is provided in that the turbocharger (7) comprises a turbine (7a) arranged in the exhaust gas removal system (6) and a compressor (7b) arranged in the intake system (5), - at least three cylinders (1, 2, 3, 4) are configured in the manner in that these form at least two groups each having at least one cylinder (1, 2, 3, 4), wherein the at least one cylinder (1, 4) of a first group has a cylinder (1, 4) which is also in operation when the internal combustion engine (10) is partially deactivated. 4) is and de r is formed at least one cylinder (2, 3) of a second group as a load-dependent switchable cylinder (2, 3), and - the exhaust pipes of at least three cylinders (1, 2, 3, 4) to form an exhaust manifold (6a) to a Total exhaust line (6b) merge, which is connected to the turbine (7a) of the at least one exhaust gas turbocharger (7), characterized in that an electrically drivable compressor (8) in the intake system (5) is arranged, - this electrically driven compressor (8 ) is in series with the compressor (7b) of the at least one exhaust gas turbocharger (7), and - for the purpose of bypassing this electrically driven compressor (8), a bypass line (9) is provided upstream of the electrically driven compressor (8) below Forming a first node (9a) from the intake system (5) branches off and downstream of the electrically driven compressor (8) to form a second node (9b) in the Ans opening system (5).

Description

• – jeder Zylinder mindestens eine Einlassöffnung aufweist, an die sich eine Ansaugleitung zum Zuführen von Ladeluft via Ansaugsystem anschließt,
• – jeder Zylinder mindestens eine Auslassöffnung aufweist, an die sich eine Abgasleitung zum Abführen der Abgase via Abgasabführsystem anschließt,
• – mindestens ein Abgasturbolader vorgesehen ist, der Abgasturbolader eine im Abgasabführsystem angeordnete Turbine und einen im Ansaugsystem angeordneten Verdichter umfasst,
• – mindestens drei Zylinder in der Art konfiguriert sind, dass diese mindestens zwei Gruppen mit jeweils mindestens einem Zylinder bilden, wobei der mindestens eine Zylinder einer ersten Gruppe ein auch bei Teilabschaltung der Brennkraftmaschine in Betrieb befindlicher Zylinder ist und der mindestens eine Zylinder einer zweiten Gruppe als lastabhängig schaltbarer Zylinder ausgebildet ist, und
• – die Abgasleitungen der mindestens drei Zylinder unter Ausbildung eines Abgaskrümmers zu einer Gesamtabgasleitung zusammenführen, welche mit der Turbine des mindestens einen Abgasturboladers verbunden ist.

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

• Each cylinder has at least one inlet opening adjoined by an intake line for supplying charge air via the intake system,
• Each cylinder has at least one outlet opening adjoined by an exhaust pipe for discharging the exhaust gases via the exhaust gas removal system,
• At least one exhaust-gas turbocharger is provided, the exhaust-gas turbocharger comprises a turbine arranged in the exhaust-gas removal system and a compressor arranged in the intake system,
• - At least three cylinders are configured in such a way that they form at least two groups each having at least one cylinder, wherein the at least one cylinder of a first group is also in partial shutdown of the internal combustion engine in operation cylinder and the at least one cylinder of a second group as load-dependent switchable cylinder is formed, and
• - Combine the exhaust gas lines of at least three cylinders to form an exhaust manifold to an overall exhaust gas line, which is connected to the turbine of the at least one exhaust gas turbocharger.

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, but also gasoline engines and hybrid internal combustion engines, d. H. Internal combustion engines, which are operated with a hybrid combustion process, and hybrid drives, which in addition to the internal combustion engine include a drive motor-connectable with the electric motor, which receives power from the internal combustion engine or emits additional power as a switchable auxiliary drive.

The internal combustion engine, which is the subject of the present invention, is an internal combustion engine charged by means of exhaust gas turbocharging. The advantage of an exhaust gas turbocharger, for example in comparison to a mechanical supercharger, is that no mechanical connection is required for transmitting power 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.

The design of the exhaust turbocharger often causes difficulties, in principle, a noticeable increase in performance in all speed ranges is sought. However, a torque drop is regularly 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 or a smaller turbine power. As a result, the boost pressure ratio and the charge pressure also decrease at lower speeds, which is equivalent to a torque drop.

Basically, the drop in charge pressure can be counteracted by a small exhaust gas turbocharger, d. H. an exhaust gas turbocharger with a small turbine cross section is used in order to generate a sufficiently high boost pressure even with small exhaust gas streams can. Ultimately, the torque drop is thus shifted only to lower speeds. In addition, this approach, d. H. The reduction of the turbine cross-section limits, since the desired charging and performance should be possible even at high speeds without restriction and to the extent desired. A small design of the turbine cross-section in combination with a Abgasabblasung is not over the entire speed range expedient and satisfactory.

The torque characteristic of a supercharged internal combustion engine is attempted to be improved by different measures according to the prior art, for example by the use of a plurality of exhaust gas turbochargers arranged in series and / or in parallel; optionally in combination with one or more mechanical loaders and / or auxiliary electrical drives.

Supercharged internal combustion engines are preferably equipped with a charge air cooling, with which the compressed combustion air is cooled before entering the cylinder. As a result, the density of the charge air supplied continues to increase. The cooling also contributes in this way to a compression and better filling of the combustion chambers, d. H. to an improved degree of filling, at. It may be advantageous to equip the intercooler with a bypass line in order to bypass the intercooler when necessary, for example, after a cold start.

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 charge leads to an increase in the Space performance and a lower power mass. If the cubic capacity is reduced, the load spectrum can be shifted to higher loads at the same vehicle boundary conditions, where the specific fuel consumption is lower.

In the development of internal combustion engines, it is a fundamental goal to minimize fuel consumption, with an improved overall efficiency in the foreground of the efforts. In this context, the charging of internal combustion engines is becoming increasingly important.

The fuel consumption and thus the efficiency, especially in gasoline engines, d. H. in spark-ignition internal combustion engines. The reason for this lies in the basic working method of the gasoline engine. The load control is usually carried out by means of a throttle valve provided 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 three cylinders, d. H. Combustion chambers. With a constant combustion chamber volume, the air mass, d. H. the quantity will be set. This also explains 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.

In order to reduce the losses described, various strategies have been developed for de-throttling a spark-ignited internal combustion engine.

One approach to dethrottling the gasoline engine is, for example, an Otto engine working method with direct injection. The direct injection of the fuel is a suitable means for realizing a stratified combustion chamber charge. The direct injection of the fuel into the combustion chamber thus allows within certain limits a quality control of the gasoline engine. The mixture formation takes place by the direct injection of the fuel in the cylinders or in the air in the cylinders and not by external mixture formation, in which the fuel is introduced into the intake system in the intake air.

Another way to optimize the combustion process of a gasoline engine, is the use of an at least partially variable valve train. In contrast to conventional valve trains, in which both the stroke of the valves and the control times are not variable, these parameters influencing the combustion process and thus the fuel consumption can be varied more or less by means of variable valve trains. Throttle-free and thus lossless load control is already possible if the closing time of the intake valve and the intake valve lift can be varied. The mixture mass flowing into the combustion chamber during the intake process is then controlled not by means of a throttle valve but via the intake valve lift and the opening duration of the intake valve.

In principle, it is the task of a valve drive to release or close the associated inlet opening or outlet opening of the cylinder in good time, with the aim of achieving rapid release of the largest possible flow cross section, in order to keep the throttling losses in the inflowing and outflowing gas flows low, and possibly as much as possible good filling of the cylinder or an effective, d. H. To ensure complete removal of the exhaust gases. Therefore, a cylinder is also often equipped with a plurality of inlet openings and outlet openings. The required for the movement of a valve valve actuating mechanism including the valve itself is referred to as a valve train. The at least one cylinder head is generally used to accommodate this valve train.

Another solution for de-throttling a gasoline engine offers the cylinder deactivation, d. H. the shutdown of individual cylinders in certain load ranges. The efficiency of the gasoline engine in partial load operation can be improved by 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 also 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.

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

The internal combustion engine, which is the subject of the present invention, is a multi-cylinder internal combustion engine with partial shutdown.

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 - as described above - is set by throttling or quantity control on the filling of the cylinder, there is room for improvement in diesel engines and improvement in terms of fuel consumption and efficiency.

A concept for reducing fuel consumption is also the cylinder deactivation in diesel engines, d. H. 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, d. H. be 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 operating cylinders, so that these cylinders operate in areas of higher loads, in which 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.

The multi-cylinder internal combustion engines with partial deactivation described in the prior art and the associated methods for operating these internal combustion engines nevertheless have clear potential for improvement.

If, for the purpose of partial shutdown, the fuel supply to the deactivatable cylinders is prevented, d. H. If the associated valve drive of this cylinder is not deactivated or can not be deactivated, the deactivated cylinders continue to participate in the charge exchange. The charge cycle losses generated thereby reduce the improvements in fuel consumption and efficiency achieved by the partial shutdown and counteract these so that the benefit of the partial shutdown is at least partially lost; H. the partial shutdown in the sum actually brings a less significant improvement.

In order to remedy the disadvantageous effects described above, it can be expedient to provide switchable or adjustable valve drives on the inlet side and on the outlet side, with which the deactivated cylinders are kept closed during the partial shutdown and thus do not continue to take part in the charge exchange. This also prevents that guided by the deactivated cylinder cooler charge air reduces the enthalpy of the exhaust gas flow provided to the turbine and cool down the deactivated cylinders quickly.

Switchable valve trains, however, may lead to further problems in internal combustion engines charged by means of exhaust-gas turbocharging, such as the internal combustion engine which is the subject of the present invention, since the turbine of an exhaust-gas turbocharger is designed for a certain amount of exhaust gas and thus regularly also for a specific number of cylinders. If the valve drive of a deactivated cylinder is deactivated, initially the total mass flow through the cylinders of the internal combustion engine is reduced. The exhaust gas mass flow guided through the turbine decreases and, with this, as a rule, also the turbine pressure ratio. A decreasing turbine performance has the consequence that the boost pressure ratio also decreases, d. H. the boost pressure drops.

In fact, the boost pressure must be increased, d. H. be increased in order to supply the more in-service cylinders more charge air, because when switching off at least one cylinder of a multi-cylinder internal combustion engine, the load on the remaining still in operation cylinder increases, which is why these cylinders more charge air and more fuel is to be supplied. The drive power available at the compressor for generating a sufficiently high charge pressure depends on the exhaust gas enthalpy of the hot exhaust gases, which is largely determined by the exhaust pressure and the exhaust gas temperature, and the exhaust gas mass or the exhaust gas flow.

In gasoline engines, the boost pressure in the load range relevant for partial shutdown can be increased in a simple manner by opening the throttle valve. This option is omitted in the diesel engine. The low charge air flow may cause the compressor to operate beyond the surge line.

The effects described above lead to a limitation of the applicability of the partial shutdown, namely a limitation of the speed range and the load range in which the partial shutdown can be used. With small charge air quantities, the boost pressure can not be increased as needed due to an insufficient compressor power or turbine power.

The charge pressure at partial shutdown and thus the still in operation cylinders supplied charge air quantity could be increased, for example, by a small design of the turbine cross-section and simultaneous Abgasabblasung, whereby the relevant for a partial shutdown load range would be extended again. However, this approach has the disadvantage that the charging behavior is insufficient when all cylinders are operated.

The charge pressure at Teilabschaltung and thus the still in operation cylinders supplied charge air quantity could also be increased by the fact that the turbine is equipped with a variable turbine geometry, which allows an adjustment of the effective turbine cross-section of the current exhaust gas flow. At the same time, however, the exhaust gas back pressure in the exhaust gas removal system upstream of the turbine would increase, which in turn leads to higher charge exchange losses in the cylinders still in operation.

For the reasons mentioned above, internal combustion engines of the type in question according to the prior art often also equipped with several parallel turbines of smaller turbine cross-section, with increasing load not only cylinders, but with the cylinders and turbines - similar to a register charging - successively switched become. The torque characteristic of the supercharged teilabschaltbaren internal combustion engine can be improved, the use of multiple superchargers or turbines always has the disadvantage of increased friction and multiple turbochargers have a worse overall efficiency than a single exhaust gas turbocharger. In addition, increase the cost and space requirements of the charge considerably when using multiple turbochargers.

In the internal combustion engine object of the present invention, the exhaust lines of the cylinders, forming a single exhaust manifold, merge into a single overall exhaust line which is connected to the turbine of an exhaust gas turbocharger. 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.

In light of the above, it is the object of the present invention to provide a supercharged internal combustion engine according to the preamble of claim 1, which is further optimized in terms of its torque characteristics and the partial shutdown.

• – jeder Zylinder mindestens eine Einlassöffnung aufweist, an die sich eine Ansaugleitung zum Zuführen von Ladeluft via Ansaugsystem anschließt,
• – jeder Zylinder mindestens eine Auslassöffnung aufweist, an die sich eine Abgasleitung zum Abführen der Abgase via Abgasabführsystem anschließt,
• – mindestens ein Abgasturbolader vorgesehen ist, der Abgasturbolader eine im Abgasabführsystem angeordnete Turbine und einen im Ansaugsystem angeordneten Verdichter umfasst,
• – mindestens drei Zylinder in der Art konfiguriert sind, dass diese mindestens zwei Gruppen mit jeweils mindestens einem Zylinder bilden, wobei der mindestens eine Zylinder einer ersten Gruppe ein auch bei Teilabschaltung der Brennkraftmaschine in Betrieb befindlicher Zylinder ist und der mindestens eine Zylinder einer zweiten Gruppe als lastabhängig schaltbarer Zylinder ausgebildet ist, und
• – die Abgasleitungen der mindestens drei Zylinder unter Ausbildung eines Abgaskrümmers zu einer Gesamtabgasleitung zusammenführen, welche mit der Turbine des mindestens einen Abgasturboladers verbunden ist, und die dadurch gekennzeichnet ist, dass ein elektrisch antreibbarer Verdichter im Ansaugsystem angeordnet ist, wobei
• – dieser elektrisch antreibbare Verdichter mit dem Verdichter des mindestens einen Abgasturboladers in Reihe schaltbar ist, und
• – zum Zwecke der Umgehung dieses elektrisch antreibbaren Verdichters eine Bypassleitung vorgesehen ist, die stromaufwärts des elektrisch antreibbaren Verdichters unter Ausbildung eines ersten Knotenpunktes vom Ansaugsystem abzweigt und stromabwärts des elektrisch antreibbaren Verdichters unter Ausbildung eines zweiten Knotenpunktes in das Ansaugsystem einmündet.

This object is achieved by a supercharged internal combustion engine with at least one cylinder head comprising at least three cylinders, in the

• Each cylinder has at least one inlet opening adjoined by an intake line for supplying charge air via the intake system,
• Each cylinder has at least one outlet opening adjoined by an exhaust pipe for discharging the exhaust gases via the exhaust gas removal system,
• At least one exhaust-gas turbocharger is provided, the exhaust-gas turbocharger comprises a turbine arranged in the exhaust-gas removal system and a compressor arranged in the intake system,
• - At least three cylinders are configured in such a way that they form at least two groups each having at least one cylinder, wherein the at least one cylinder of a first group is also in partial shutdown of the internal combustion engine in operation cylinder and the at least one cylinder of a second group as load-dependent switchable cylinder is formed, and
• - Merge the exhaust gas lines of at least three cylinders to form an exhaust manifold to an overall exhaust gas line, which is connected to the turbine of the at least one exhaust gas turbocharger, and which is characterized in that an electrically drivable compressor is arranged in the intake system, wherein
• - This electrically driven compressor with the compressor of at least one exhaust gas turbocharger is connected in series, and
• - For the purpose of circumventing this electrically driven compressor, a bypass line is provided which branches off upstream of the electrically driven compressor to form a first node of the intake system and opens downstream of the electrically driven compressor to form a second node in the intake system.

The inventive supercharged by exhaust gas turbocharger internal combustion engine is equipped with an additional compressor, which in the present case is an electrically driven compressor, so that there is no mechanical connection to the power transmission between the compressor and internal combustion engine or is required. The electrically driven compressor is therefore characterized by a small space requirement. This allows a dense Packaging of the charge and thus the internal combustion engine.

Another advantage of the electrically driven compressor is that the electrically driven compressor can generate and provide the requested boost pressure - in contrast to the turbocharger regardless of the current operating state of the internal combustion engine, especially at low exhaust gas quantities or low speeds of the crankshaft.

The electrically driven compressor is inventively designed as a switchable compressor, which is switched on when needed, namely at the transition to partial shutdown, in order to support the compressor of at least one exhaust gas turbocharger to contribute to the compression of the charge air or cooperate in generating the required charge pressure.

As already discussed, in a partial shutdown of the internal combustion engine, the boost pressure must be increased in order to be able to supply more charge air to the further operating cylinders whose load increases in the operating mode of partial shutdown.

The available at the compressor of the exhaust gas turbocharger drive power to generate the boost pressure depends on the exhaust enthalpy of the hot exhaust gases and the total mass flow through the cylinders of the engine, so the compressor power at the transition to partial shutdown can not be readily increased demand. The electrically drivable compressor closes this gap, which results from the turbine power too low or compressor output of the exhaust gas turbocharger.

During the transition to partial shutdown, the charge air is compressed in two stages using the electrically driven compressor and the compressor of the at least one exhaust gas turbocharger, as a result of which the boost pressure can be increased. As a result, more charge air can and will be supplied to the cylinders which are still in operation. The total mass flow through the cylinders of the internal combustion engine is increased and thus also the exhaust gas flow through the turbine of the at least one exhaust gas turbocharger. The turbine power and thus the available compressor capacity of the exhaust gas turbocharger increase. The compressor of the at least one exhaust gas turbocharger is after a transition phase, even without support able to generate the required boost pressure in the intake downstream of the compressor.

The electrically driven compressor is switched off as soon as the partially switched-off internal combustion engine runs stable, d. H. the requirement described above no longer exists.

The electrically driven compressor can also be used in normal operation of the internal combustion engine to improve the torque characteristics at low speeds or small amounts of exhaust gas.

With the internal combustion engine according to the invention an internal combustion engine according to the preamble of claim 1 is provided, which is further optimized in terms of their torque characteristics and the partial shutdown. Thus, the object underlying the invention is achieved.

The internal combustion engine according to the invention has at least three cylinders or at least two groups each having at least one cylinder. As such, three-cylinder engines configured in three groups of one cylinder each, or six-cylinder engines configured in three groups of two cylinders, are also internal combustion engines of the present invention. The three cylinder groups can be successively switched on or off as part of a partial shutdown, whereby a two-time switching can be realized. The partial shutdown is thereby further optimized. The cylinder groups may also comprise a different number of cylinders.

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

Advantageous embodiments of the supercharged internal combustion engine, in which the bypass line is equipped with a shut-off.

This shut-off allows by opening the bypass and thus the deactivation of the electrically driven compressor, if a single-stage compression or charging to be realized using the exhaust gas turbocharger. But with this shut-off can also control the amount of charge air supplied to the electrically driven compressor, d. H. to adjust. This is of relevance in particular in the phase of operation of the internal combustion engine, in which the electrically driven compressor is or will be switched off again.

Embodiments of the supercharged internal combustion engine in which a charge air cooler is arranged in the intake system downstream of the compressor are advantageous. The intercooling lowers the temperature and increases the density of the compressed charge air and thus contributes to another Compression and better filling of the cylinders in operation. A bypass line for bypassing the intercooler may be advantageous, for example after a cold start.

Embodiments of the supercharged internal combustion engine in which the electrically drivable compressor is arranged downstream of the compressor of the at least one exhaust gas turbocharger in the intake system are advantageous.

Embodiments of the supercharged internal combustion engine in which the bypass line between the electrically drivable compressor and the compressor of the at least one exhaust gas turbocharger branches off from the intake system to form a first node are advantageous. Then the bypass line is used exclusively to bypass the electrically driven compressor.

In this context, embodiments of the supercharged internal combustion engine in which a further charge air cooler is provided, which is arranged between the electrically drivable compressor and the first node in the intake system, are advantageous. Then, the bypass line serves to bypass the electrically driven compressor and the other intercooler.

Embodiments of the supercharged internal combustion engine in which a further charge air cooler is provided, which is arranged between the compressor of the at least one exhaust gas turbocharger and the first node in the intake system, can also be advantageous in this context. Then the bypass line is used to bypass the electrically driven compressor, but no longer the bypass of the other intercooler.

According to the last two embodiments, between the compressors, i. H. disposed between the compressor of the at least one exhaust gas turbocharger and the electrically driven compressor, another intercooler, the temperature of the precompressed charge air between the compressors lowers and thus increases the density of the charge air before entering the downstream electrically driven compressor in a two-stage compression. As a result, the compression is improved in the electrically driven compressor and lowered the outlet temperature from this compressor at the same total pressure ratio of the Aufladegruppe. But it can also increase the overall pressure ratio of the compressor group and thus the boost pressure. In any case, the further intercooler contributes to a better filling of the cylinders in operation.

Embodiments of the supercharged internal combustion engine in which the electrically drivable compressor is arranged upstream of the compressor of the at least one exhaust gas turbocharger in the intake system are also advantageous.

If the electrically drivable compressor is not arranged downstream, but upstream of the compressor of the at least one exhaust-gas turbocharger, this compressor serves as a low-pressure stage and not as a high-pressure stage in the context of a two-stage compression.

Embodiments of the supercharged internal combustion engine in which the bypass line between the electrically drivable compressor and the compressor of the at least one exhaust gas turbocharger opens into the intake system to form a second node point are advantageous. Then the bypass line is used exclusively to bypass the electrically driven compressor.

In this context, embodiments of the supercharged internal combustion engine in which a further charge air cooler is provided which is arranged between the electrically drivable compressor and the second node in the intake system are advantageous. Then, the bypass line serves to bypass the electrically driven compressor and the other intercooler.

Embodiments of the supercharged internal combustion engine in which a further intercooler is provided, which is arranged between the compressor of the at least one exhaust gas turbocharger and the second node in the intake system, can also be advantageous in this context. Then the bypass line is used to bypass the electrically driven compressor, but no longer the bypass of the other intercooler.

It is true that in connection with the other intercooler said in an analogous manner, which is why reference is made to the corresponding statements.

Embodiments of the supercharged internal combustion engine in which the turbine of the at least one exhaust-gas turbocharger has a fixed turbine geometry are advantageous. A solid turbine geometry is inexpensive. For a satisfactory torque characteristic, it may be useful to run the turbine as a waste gate turbine.

Embodiments of the supercharged internal combustion engine in which the turbine of the at least one exhaust-gas turbocharger has a variable turbine geometry are also advantageous.

A variable turbine geometry increases the flexibility of charging. It allows a continuous adjustment of the turbine geometry to the respective operating point of the internal combustion engine or to the current exhaust gas mass flow. 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. Although the guide vanes are arranged stationary, 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, as far as guide vanes are provided or a guide is provided.

In particular, the combination of turbine with variable turbine geometry and compressor with variable compressor geometry allows to achieve high boost pressures even with very small amounts of exhaust gas.

Embodiments of the supercharged internal combustion engine in which the compressor of the at least one exhaust-gas turbocharger has a variable compressor geometry are advantageous. In particular, if only a small amount of exhaust gas is passed through the turbine, a variable compressor geometry proves to be advantageous because the surge limit of the compressor by adjusting the vanes in the compressor map to small

Compressor streams can be moved and so working of the compressor is avoided beyond the surge line. The variable compressor geometry therefore also offers advantages when large amounts of exhaust gas are branched off and returned upstream of the turbine in order to achieve high return rates. If the turbine of the at least one exhaust-gas turbocharger has a variable turbine geometry, the variable compressor geometry can be continuously matched to the turbine geometry.

Embodiments of the supercharged internal combustion engine in which the electrically drivable compressor is designed to be smaller than the compressor of the at least one exhaust gas turbocharger are advantageous. This is advantageous in particular in embodiments in which the electrically drivable compressor is arranged downstream of the compressor of the at least one exhaust gas turbocharger in the intake system and serves as a high-pressure stage in the context of a two-stage compression.

Embodiments of the supercharged internal combustion engine in which only one exhaust-gas turbocharger is provided are advantageous. In normal operation of the internal combustion engine is then regularly a single-stage charge or compression. With respect to the frictional power and the overall efficiency, it is more advantageous to use a single exhaust gas turbocharger instead of a plurality of turbochargers, and therefore, the above embodiment has advantages in efficiency.

In internal combustion engines with four cylinders arranged in series, embodiments are advantageous in which the two outer cylinders and the two inner cylinders each form a group.

Advantageous embodiments of the supercharged internal combustion engine, in which at least one exhaust gas recirculation is provided, which includes a return line, which branches off from the Abgasabführsystem and opens into the intake system.

The exhaust gas recirculation, ie the recirculation of combustion gases, is a suitable means to reduce the nitrogen oxide emissions, with the exhaust gas recirculation rate can be significantly reduced with increasing exhaust gas recirculation rate. In this case, the exhaust gas recirculation rate x _{AGR is} determined to be x _AGR = m _AGR / (m _AGR + m _{fresh air} ), where m _{AGR is} the mass of recirculated exhaust gas and m _{fresh air is} the supplied and possibly fresh air guided and compressed by a compressor. In order to achieve a significant reduction in nitrogen oxide emissions, high exhaust gas recirculation rates are required, which can be on the order of x _EGR ≈ 60% to 70%.

Embodiments of the supercharged internal combustion engine in which a shut-off element for adjusting the recirculated exhaust gas quantity is arranged in the return line of the exhaust gas recirculation are advantageous.

In supercharged internal combustion engines with at least one exhaust gas turbocharger and exhaust gas recirculation embodiments are advantageous in which the return line of the exhaust gas recirculation upstream of the turbine of the at least one exhaust gas turbocharger branches off from Abgasabführsystem and preferably opens downstream of the compressor or the compressor in the intake system. In this so-called high-pressure EGR, the exhaust gas is taken from the Abgasabführsystem upstream of the turbine and fed downstream of the compressor in the intake system, which is why the exhaust before recirculation subjected no exhaust aftertreatment, in particular no particulate filter must be supplied as contamination of the compressor or the Compressor is not to be feared.

When operating an internal combustion engine with exhaust gas turbocharging and simultaneous use of a high-pressure EGR, however, a conflict may arise because the recirculated exhaust gas is no longer available for driving the turbine. With an increase in the exhaust gas recirculation rate, the exhaust gas flow introduced into the turbine decreases. The reduced exhaust gas mass flow through the turbine causes a smaller turbine pressure ratio, as a result of which the boost pressure ratio or the boost pressure likewise decreases.

One solution to this problem is the so-called low-pressure EGR. In contrast to the high-pressure EGR, exhaust gas is introduced into the intake system in the low-pressure EGR, which has already passed through the turbine. For this purpose, the low-pressure EGR has a return line, which branches off downstream of the turbine from the Abgasabführsystem and preferably flows into the intake system upstream of the compressor or the compressor.

Embodiments of the supercharged internal combustion engine may therefore be advantageous in which a low-pressure EGR is provided instead of a high-pressure EGR or in addition to a high-pressure EGR.

To operate an internal combustion engine of the type described above with only one exhaust gas turbocharger, the electrically driven compressor is switched to support the compressor of the exhaust gas turbocharger in a transition to an operating mode of the partial shutdown, according to which the at least one switchable cylinder of the second group is switched off generate sufficiently high specifiable boost pressure in the intake system downstream of the compressor.

Preferably, the electrically driven compressor is switched off as soon as the operating mode of partial deactivation of the partially switched-off internal combustion engine is stable, such that the compressor of the exhaust gas turbocharger is capable of providing a sufficiently high predefinable boost pressure in the intake system downstream of the compressor without assistance.

In the following the invention is based on an embodiment of a supercharged internal combustion engine and according to 1 explained in more detail. Hereby shows:

1 schematically a first embodiment of the internal combustion engine.

1 schematically shows a first embodiment of the supercharged internal combustion engine 10 that with an exhaust gas turbocharger 7 equipped, the one in the exhaust system 6 arranged turbine 7a and one in the intake system 5 arranged compressor 7b includes. The hot exhaust gas relaxes in the turbine 7a under energy release. The compressor 7b compresses the charge air via the intake system 5 and intercooler 11 the cylinders 1 . 2 . 3 . 4 is supplied, whereby a charge of the internal combustion engine 10 is reached.

It is a four-cylinder in-line engine 10 in which the four cylinders 1 . 2 . 3 . 4 along the longitudinal axis of the cylinder head, that are arranged in series. The four cylinders 1 . 2 . 3 . 4 are configured and form two groups with two cylinders each 1 . 2 . 3 . 4 , where the two inner cylinders 2 . 3 form a second group whose cylinder 2 . 3 as a load-dependent switchable cylinder 2 . 3 are formed, which are turned off in the context of a partial shutdown, and the two outer cylinder 1 . 4 form a first group whose cylinder 1 . 4 are also in partial shutdown in operation.

The exhaust pipes of the cylinders 1 . 2 . 3 . 4 lead to the formation of an exhaust manifold 6a to an entire exhaust line 6b together. The total exhaust gas line 6b leads to the turbine 7a the exhaust gas turbocharger 7

An electrically driven compressor 8th is additionally in the intake system 5 arranged, which deals with the compressor 7b the exhaust gas turbocharger 7 can be switched in series. The electrically driven compressor 8th is as a switchable compressor 8th if necessary, namely at the transition to partial shutdown, in order to support the compressor 7b the exhaust gas turbocharger 7 can be switched to the further operating cylinders 1 . 4 be able to supply sufficient charge air.

In the present case is the electrically driven compressor 8th downstream of the compressor 7b the exhaust gas turbocharger 7 in the intake system 5 arranged, with the purpose of bypassing the electrically driven compressor 8th a bypass line 9 is provided between the electrically driven compressor 8th and the compressor 7b the exhaust gas turbocharger 7 forming a first node 9a from the intake system 5 branches off and downstream of the electrically driven compressor 8th forming a second node 9b into the intake system 5 opens.

LIST OF REFERENCE NUMBERS

1

 first cylinder, outboard cylinder

2

 second cylinder, internal cylinder, switchable cylinder

3

 third cylinder, internal cylinder, switchable cylinder

4

 fourth cylinder, outboard cylinder

5

 intake system

6

 Abgasabführsystem

6a

 exhaust manifold

6b

 Total exhaust pipe

7

 turbocharger

7a

 Turbine of the exhaust gas turbocharger

7b

 Compressor of the exhaust gas turbocharger

8th

 electrically driven compressor

9

 bypass line

9a

 first node

9b

 second node

9c

 shut-off

10

 Internal combustion engine, four-cylinder in-line engine

11

 Intercooler

Claims (16)

Charged internal combustion engine ( 10 ) with at least one cylinder head comprising at least three cylinders ( 1 . 2 . 3 . 4 ), in which - each cylinder ( 1 . 2 . 3 . 4 ) has at least one inlet opening, to which a suction line for supplying charge air via the intake system ( 5 ), - each cylinder ( 1 . 2 . 3 . 4 ) has at least one outlet opening, to which an exhaust pipe for discharging the exhaust gases via Abgasabführsystem ( 6 ), - at least one exhaust gas turbocharger ( 7 ) is provided, the exhaust gas turbocharger ( 7 ) in the exhaust gas removal system ( 6 ) arranged turbine ( 7a ) and one in the intake system ( 5 ) arranged compressors ( 7b ), - at least three cylinders ( 1 . 2 . 3 . 4 ) are configured in such a way that these at least two groups each having at least one cylinder ( 1 . 2 . 3 . 4 ), wherein the at least one cylinder ( 1 . 4 ) a first group also at partial shutdown of the internal combustion engine ( 10 ) operating cylinder ( 1 . 4 ) and the at least one cylinder ( 2 . 3 ) of a second group as a load-dependent switchable cylinder ( 2 . 3 ), and - the exhaust pipes of the at least three cylinders ( 1 . 2 . 3 . 4 ) with formation of an exhaust manifold ( 6a ) to an overall exhaust gas line ( 6b ), which with the turbine ( 7a ) of the at least one exhaust gas turbocharger ( 7 ), characterized in that an electrically driven compressor ( 8th ) in the intake system ( 5 ), wherein - this electrically driven compressor ( 8th ) with the compressor ( 7b ) of the at least one exhaust gas turbocharger ( 7 ) is switchable in series, and - for the purpose of bypassing this electrically driven compressor ( 8th ) a bypass line ( 9 ) provided upstream of the electrically driven compressor ( 8th ) forming a first node ( 9a ) from the intake system ( 5 ) branches off and downstream of the electrically driven compressor ( 8th ) forming a second node ( 9b ) into the intake system ( 5 ). Charged internal combustion engine ( 10 ) according to claim 1, characterized in that the bypass line ( 9 ) with a shut-off element ( 9c ) Is provided. Charged internal combustion engine ( 10 ) according to claim 1 or 2, characterized in that downstream of the compressor ( 7b . 8th ) a charge air cooler ( 11 ) in the intake system ( 5 ) is arranged. Charged internal combustion engine ( 10 ) according to one of the preceding claims, characterized in that the electrically driven compressor ( 8th ) downstream of the compressor ( 7b ) of the at least one exhaust gas turbocharger ( 7 ) in the intake system ( 5 ) is arranged. Charged internal combustion engine ( 10 ) according to claim 4, characterized in that the bypass line ( 9 ) between the electrically driven compressor ( 8th ) and the compressor ( 7b ) of the at least one exhaust gas turbocharger ( 7 ) forming a first node ( 9a ) from the intake system ( 5 ) branches off. Charged internal combustion engine ( 10 ) according to claim 5, characterized in that a further intercooler is provided, which between the electrically driven compressor ( 8th ) and the first node ( 9a ) in the intake system ( 5 ) is arranged. Charged internal combustion engine ( 10 ) according to claim 5, characterized in that a further intercooler is provided, which between the compressor ( 7b ) of the at least one exhaust gas turbocharger ( 7 ) and the first node ( 9a ) in the intake system ( 5 ) is arranged. Charged internal combustion engine ( 10 ) according to one of claims 1 to 3, characterized in that the electrically driven compressor ( 8th ) upstream of the compressor ( 7b ) of the at least one exhaust gas turbocharger ( 7 ) in the intake system ( 5 ) is arranged. Charged internal combustion engine ( 10 ) according to claim 8, characterized in that the bypass line ( 9 ) between the electrically driven compressor ( 8th ) and the compressor ( 7b ) of the at least one exhaust gas turbocharger ( 7 ) forming a second node ( 9b ) into the intake system ( 5 ). Charged internal combustion engine ( 10 ) according to claim 9, characterized in that a further intercooler is provided, which between the electrically driven compressor ( 8th ) and the second node ( 9b ) in the intake system ( 5 ) is arranged. Charged internal combustion engine ( 10 ) according to claim 9, characterized in that a further intercooler is provided, which between the compressor ( 7b ) of the at least one exhaust gas turbocharger ( 7 ) and the second node ( 9b ) in the intake system ( 5 ) is arranged. Charged internal combustion engine ( 10 ) according to one of the preceding claims, characterized in that the turbine ( 7a ) of the at least one exhaust gas turbocharger ( 7 ) has a variable turbine geometry. Charged internal combustion engine ( 10 ) according to one of the preceding claims, characterized in that the compressor ( 7b ) of the at least one exhaust gas turbocharger ( 7 ) has a variable compressor geometry. Charged internal combustion engine ( 10 ) according to one of the preceding claims, characterized in that the electrically driven compressor ( 8th ) is designed smaller than the compressor ( 7b ) of the at least one exhaust gas turbocharger ( 7 ). Charged internal combustion engine ( 10 ) according to one of the preceding claims, characterized in that only one exhaust gas turbocharger ( 7 ) is provided. Charged internal combustion engine ( 10 ) according to one of the preceding claims with four cylinders arranged in series ( 1 . 2 . 3 . 4 ), characterized in that the two outer cylinders ( 1 . 4 ) and the two inner cylinders ( 2 . 3 ) each form a group.

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