DE102013208512A1 - Supercharged internal combustion engine with deactivatable cylinder and method of operating such an internal combustion engine - Google Patents

Abstract

The invention relates to a BKM (13) with min. two cylinders (1, 2, 3, 4), in which - each cylinder. (1, 2, 3, 4) min. has an outlet opening to which an exhaust pipe (7a, 7b) connects, - each cyl. (1, 2, 3, 4) min. has an inlet opening to which an intake line (5a, 5b) connects, - min. two cyl. (1, 2, 3, 4) are configured in such a way that these min. two groups with min. a cyl. (1, 2, 3, 4) form, the min. a cyl. (1,4) a first group a cyl in operation even with partial shutdown of the internal combustion engine (13). (1, 4) and the min. a cyl. (2, 3) a second group as a load-dependent switchable cylinder. (2, 3) is formed, - min. an EGR (10, 15) is provided, and - min. An exhaust gas turbocharger (12) is provided, which comprises a turbine (12a) and a compressor (12b), the exhaust pipes (7a, 7b) of the cylinder. (1, 2, 3, 4) of each cylinder group to form an exhaust manifold to form a total exhaust pipe (7A, 7B), and - the two total exhaust pipes (7A, 7B) with a double-flow turbine (12a), the min. comprises an impeller (19) mounted in a turbine housing (18) on a rotatable shaft (19a), connected in such a way that a total exhaust pipe (7A, 7B) is connected to one of the two inlet openings of the turbine (12a), whereby a flood (17A, 17B) of the turbine (12a) adjoins each inlet opening and a first shut-off element (20) is provided which, in a first working position, blocks the second flood (17B) assigned to the second cylinder group and is separated from the min. separates an impeller (19) and in a second working position releases this second flood (17B) and with the min. connects an impeller (19).

Description

• – jeder Zylinder mindestens eine Auslassöffnung aufweist, an die sich eine Abgasleitung zum Abführen der Abgase via Abgasabführsystem anschließt,
• – jeder Zylinder mindestens eine Einlassöffnung aufweist, an die sich eine Ansaugleitung zum Zuführen von Ladeluft via Ansaugsystem anschließt,
• – mindestens zwei 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,
• – mindestens eine Abgasrückführung vorgesehen ist, und
• – mindestens ein Abgasturbolader vorgesehen ist, der eine im Abgasabführsystem angeordnete Turbine und einen im Ansaugsystem angeordneten Verdichter umfasst.

The invention relates to a supercharged internal combustion engine having at least two cylinders, wherein

• Each cylinder has at least one outlet opening adjoined by an exhaust pipe for discharging the exhaust gases via the exhaust gas removal system,
• Each cylinder has at least one inlet opening adjoined by an intake line for supplying charge air via the intake system,
• - At least two 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 deactivation 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,
• - At least one exhaust gas recirculation is provided, and
• - At least one exhaust gas turbocharger is provided which comprises a turbine arranged in the Abgasabführsystem and a compressor arranged in the intake system.

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

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

In 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.

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 two 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.

To reduce the losses described, various strategies for de-throttling a gasoline engine have been developed.

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 or charge air mass flowing into the combustion chamber during the intake process is then not controlled by means of a throttle valve, but via the intake valve stroke and the opening duration of the intake valve. However, variable valve trains are very cost-intensive and therefore often unsuitable for serial installation.

Another solution for dethrottling a gasoline engine offers the cylinder deactivation, ie the shutdown of individual cylinders in certain load ranges. The efficiency of the gasoline engine in partial load operation can be improved by such a partial shutdown, ie increased, because the shutdown of a cylinder of a multi-cylinder Internal combustion engine increases at constant engine power, the load of the remaining cylinders still in operation, so that the throttle valve for introducing a larger air mass in these cylinders can be opened or must, whereby 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 - as described above - is set by throttling or quantity control on the filling of the cylinder, there is also improvement potential in diesel engines and improvement in 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.

The further operated during the partial shutdown cylinders also tolerate due to the larger fuel mass supplied, d. H. due to the richer mixture, higher exhaust gas recirculation rates. 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 internal combustion engine according to the invention is a suitable for partial shutdown internal combustion engine, d. H. an internal combustion engine with at least one deactivatable cylinder.

The multi-cylinder internal combustion engines with partial deactivation described in the prior art and the associated methods for operating these internal combustion engines have a clear potential for improvement, as will be explained in the following briefly and by way of example on the diesel engine.

Is in a direct-injection diesel engine for the purpose of partial shutdown, the fuel supply to the disabled cylinders 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 by the deactivated cylinders 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, ie. H. the partial shutdown in the sum actually brings a less significant improvement.

In practice, it is not expedient to remedy the disadvantageous effects described above, characterized in that switchable valve trains are provided because switchable valve trains such as variable valve trains are very costly and are not suitable for mass production.

In addition, switchable valve trains would result in turbocharged supercharged by exhaust gas turbochargers to further problems, since the turbine of an exhaust gas turbocharger is to be interpreted to a certain amount of exhaust gas and thus to a certain number of cylinders. When the valve train of a deactivated cylinder is deactivated, the total mass flow through the cylinders of the internal combustion engine decreases due to the lack of mass flow through the deactivated cylinders. The exhaust gas mass flow guided through the turbine decreases and with it the turbine pressure ratio. This has the consequence that the boost pressure ratio also decreases, d. H. the charge pressure drops, and only a little fresh air or charge air is supplied or can be supplied to the cylinders which are still in operation. The low charge air flow can also 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 to a limitation of the load range in which the partial shutdown can be used. The reduced charge air quantity, which is supplied to the operating during the partial shutdown cylinders, also reduces the effectiveness or quality of the combustion and has an adverse effect on fuel consumption and pollutant emissions.

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 to the current exhaust gas mass 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.

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 terms of partial shutdown and turbocharging.

It is another object of the present invention to provide a method of operating such a supercharged internal combustion engine.

• – jeder Zylinder mindestens eine Auslassöffnung aufweist, an die sich eine Abgasleitung zum Abführen der Abgase via Abgasabführsystem anschließt,
• – jeder Zylinder mindestens eine Einlassöffnung aufweist, an die sich eine Ansaugleitung zum Zuführen von Ladeluft via Ansaugsystem anschließt,
• – mindestens zwei 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,
• – mindestens eine Abgasrückführung vorgesehen ist, und
• – mindestens ein Abgasturbolader vorgesehen ist, der eine im Abgasabführsystem angeordnete Turbine und einen im Ansaugsystem angeordneten Verdichter umfasst, die dadurch gekennzeichnet ist, dass
• – die Abgasleitungen der Zylinder jeder Zylindergruppe unter Ausbildung eines Abgaskrümmers jeweils zu einer Gesamtabgasleitung zusammenführen, und
• – die beiden Gesamtabgasleitungen mit einer zweiflutigen Turbine, die mindestens ein in einem Turbinengehäuse auf einer drehbaren Welle gelagertes Laufrad umfasst, in der Art verbunden sind, dass jeweils eine Gesamtabgasleitung mit einer der beiden Eintrittsöffnungen der Turbine verbunden ist, wobei sich an jede Eintrittsöffnung eine Flut der Turbine anschließt und ein erstes Absperrelement vorgesehen ist, welches in einer ersten Arbeitsposition die der zweiten Zylindergruppe zugeordnete zweite Flut versperrt und von dem mindestens einen Laufrad trennt und in einer zweiten Arbeitsposition diese zweite Flut freigibt und mit dem mindestens einen Laufrad verbindet.

The first sub-task is solved by a supercharged internal combustion engine with at least two cylinders, in the

• Each cylinder has at least one outlet opening adjoined by an exhaust pipe for discharging the exhaust gases via the exhaust gas removal system,
• Each cylinder has at least one inlet opening adjoined by an intake line for supplying charge air via the intake system,
• - At least two 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 deactivation 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,
• - At least one exhaust gas recirculation is provided, and
• At least one exhaust-gas turbocharger is provided which comprises a turbine arranged in the exhaust-gas removal system and a compressor arranged in the intake system, which is characterized in that
• - Combine the exhaust gas lines of the cylinder of each cylinder group to form an exhaust manifold to form an overall exhaust line, and
• - The two total exhaust gas lines with a double-flow turbine, which comprises at least one mounted in a turbine housing on a rotatable shaft impeller are connected in such a way that in each case an overall exhaust gas line is connected to one of the two inlet openings of the turbine, wherein at each inlet opening a flood the turbine connects and a first shut-off is provided which blocks the second cylinder group associated second flood in a first working position and separated from the at least one impeller and in a second working position releases this second flood and connects to the at least one impeller.

The internal combustion engine according to the invention is equipped with a twin-flow turbine, whereby the charging behavior, d. H. the torque characteristic is significantly improved, especially during partial shutdown.

The second flood associated with the switchable cylinders is blocked by means of a shut-off element during partial shut-off. This prevents exhaust gas from the cylinders, which are still in operation, from overflowing into the second tide. In this way, the dynamic wave processes occurring in the exhaust gas removal system can be used to improve the charging behavior.

In this context, it has to be taken into consideration that the evacuation of the combustion gases from a cylinder during the change of charge is essentially based on two different mechanisms. When the exhaust valve opens at the beginning of the charge cycle, the combustion gases flow at high speed through the exhaust port into the exhaust gas discharge system due to the high pressure level prevailing in the cylinder at the end of the combustion and the associated high pressure difference between the combustion chamber and the exhaust pipe. This pressure-driven flow process is accompanied by a high pressure peak, which also serves as a preflash is referred to and propagates along the exhaust pipe at the speed of sound, wherein the pressure with increasing distance due to friction degrades more or less, ie reduced. In the course of the charge cycle, the pressures in the cylinder and in the exhaust line are the same, so that the combustion gases are primarily not evacuated pressure driven, but are ejected as a result of the stroke of the piston.

The high pressure pulses of the Vorlassstöße can be used for shock charging, which is why it is advantageous to obtain the pressure pulses in Abgasabführsystem and take action so that the pressure pulses of the individual cylinders do not weaken each other or cancel.

In this case, the internal combustion engine according to the invention can be purposeful, in which the second flood of the turbine is shut off with shut-off by means of shut-off, so that the pressure pulses of the further in-service cylinder can not spread in this second flood and reduce or weaken, the in the second tide between the at least one deactivated cylinder and the impeller exhaust volume located would eliminate a damping effect.

In particular, in the context of a partial shutdown, at low loads and low speeds at which the frequency of pressure fluctuations decreases in Abgasabführsystem, the internal combustion engine according to the invention proves to be particularly advantageous, for example, to improve the torque at low speeds, d. H. to raise.

In the internal combustion engine according to the invention, moreover, the removal of the exhaust gas from the at least one deactivated cylinder via Abgasabführsystem is prevented during partial shutdown, without the switchable cylinder with switchable valve drives, which cause high costs must be equipped. The first shut-off locked in the first working position, the second flood and thus the exhaust pipes of the load-dependent switchable cylinder. Although the at least one deactivated cylinder continues to participate in the charge exchange, if the associated valve train of this cylinder is operated further and is not deactivated. However, the at least one deactivated cylinder promotes into the exhaust gas volume located between its outlet openings and the first shut-off element and not through the turbine.

With the internal combustion engine according to the invention, a supercharged internal combustion engine according to the preamble of claim 1 is provided, which is improved in terms of partial shutdown and turbocharging. Thus, the first object of the invention is solved.

The internal combustion engine according to the invention has at least two 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, for example, in a three-cylinder engine, forming a one-cylinder group and a two-cylinder group.

The embodiment of the invention improves the efficiency of the internal combustion engine in partial load operation, d. H. at low loads, where a low load is preferably a load that is less than 50%, preferably less than 30%, of the maximum load at the instantaneous speed.

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

Embodiments of the supercharged internal combustion engine in which the first shut-off element is provided at the impeller-side end of the second flood are advantageous. As a result, the exhaust gas volume located between the first shut-off element and the impeller is minimized and an overflow of the exhaust gas originating from the cylinders in operation is optimally prevented from the first flood into the second flood, ie. H. prevented. An optimization of the shock charging is the result.

Embodiments of the supercharged internal combustion engine in which the two flows or the two total exhaust gas lines or the exhaust manifolds of the cylinder groups can be connected to one another, are advantageous. H. have at least one connection.

In this context, embodiments of the supercharged internal combustion engine in which the two floods in the turbine housing are separated from each other by means of a housing wall are advantageous. The housing wall ends on the impeller side and ends at least one impeller, thus forming a connection between the two floods at its end on the impeller side ,

The bump charging described in detail above also has disadvantages. As a rule, the charge cycle deteriorates as a result of the pressure pulses in the exhaust gas removal system. The cylinders can interfere with each other during the charge cycle, ie impair. The pressure waves emanating from a cylinder, not only run through the exhaust pipe of this cylinder, but also along the exhaust pipes of the other cylinder and possibly up to the outlet opening, which is why already discharged exhaust gas can get into these cylinders again.

Furthermore, it must be considered that a turbine can be operated most effectively when the turbine is subjected to a constant exhaust gas pressure. With regard to the highest possible turbine efficiency, therefore, a little changing pressure upstream of the turbine, d. H. of the impeller, preferably in order to realize a so-called congestion charge.

By a corresponding or largest possible volume of exhaust gas upstream of the turbine, the pressure pulsations in the exhaust pipes can be smoothed. In this respect, a separation of the floods up to the impeller, in which the volume of Abgasabführsystems upstream of the impeller is divided into several sub-volumes, would be extremely disadvantageous. With regard to a static charge, it is therefore advantageous to connect the two floods of the turbine and thus the two exhaust manifolds of the cylinder groups with each other.

The embodiment in question therefore provides a connection between the two floods. The provided in the turbine housing housing wall separates the floods as long as possible from each other and until just before the impeller.

In order to change from the surge charging at partial shutdown to a congestion charging operation of all cylinders, it is necessary to be able to open or close the connection between the floods.

Since the internal combustion engine according to the invention already has a first shut-off element, which is transferred for the purpose of partial shutdown of a second working position to a first working position to obstruct the second flood associated with the at least one deactivated cylinder, it would be extremely advantageous for this first shut-off also for the To be able to use or to use opening and closing the connection between the floods.

Therefore, embodiments of the supercharged internal combustion engine in which the first shut-off element is provided at the impeller-side end of the second flood and blocks the connection in the first working position and releases it in the second working position are particularly advantageous.

Embodiments of the supercharged internal combustion engine in which the first shut-off element connects the second flow to a return line and separates the second flow from this return line in the second operating position are advantageous, with the return line leading into the intake line of the at least one load-dependent switchable cylinder.

According to this embodiment, the gas flow or the exhaust gas flow from the deactivated cylinders is not only blocked, but rather diverted, namely recycled. The deactivated cylinders, no charge air is supplied during the partial shutdown of the internal combustion engine, but rather exhaust gas from its own exhaust line, which is introduced via return line in the intake of the deactivated cylinder to reduce the charge cycle losses of the deactivated cylinder. The return line serves as a short-circuit line and causes a pressure equalization between the inlet side and the outlet side of a deactivated cylinder. This contributes significantly to the reduction of charge exchange losses. The shut-off cylinders pump the recirculated exhaust gas in the manner of a compressor from the inlet side to the outlet side.

By passing hot exhaust gas through the deactivated cylinders during partial shutdown, these cylinders can not cool. This has advantages in particular with regard to the pollutant emissions, in particular with regard to the emissions of unburned hydrocarbons, since the deactivated cylinders again reach or have their operating temperature immediately after termination of the partial shutdown. Strictly speaking, not permanently hot exhaust gas is returned via the return line during partial shutdown, but at least during the first cycle of partial shutdown the exhaust gas of the previous and thus the hot exhaust gas of the last fired work cycle. During the following cycles of partial shutdown then slowly cooling exhaust gas is introduced with a more or less large amount of cooler charge air in the at least one deactivated cylinder. Nevertheless, in the present case the recirculation of hot exhaust gas is mentioned, so that in the present case it is also an exhaust gas recirculation within the meaning of the preamble of claim 1.

Embodiments of the supercharged internal combustion engine in which a second shut-off element is provided in the return line are advantageous. The second shut-off serves the Adjustment of the recirculated exhaust gas quantity or the pressure gradient between the inlet side and the outlet side of a deactivated cylinder. In this respect, the second shut-off can also be used to keep the amount of exhaust gas during the partial shutdown constant, ie the same size.

Embodiments of the supercharged internal combustion engine in which a third shut-off element is provided in the intake line of the at least one load-dependent cylinder which releases the intake line for supplying charge air with the cylinder switched on and blocks when the cylinder is switched off are advantageous, and the return line downstream of this third shut-off element into the Inlet line of the at least one load-dependent switchable cylinder opens.

According to this embodiment, the deactivated cylinders are supplied during the partial shutdown no charge air, but only exhaust gas from the own exhaust gas line. For this purpose, the suction lines of the deactivated cylinders are closed by means of shut-off elements, wherein the return line opens downstream of the shut-off elements in the suction lines separated from the suction side. It is therefore a one hundred percent exhaust gas recirculation.

Embodiments of the supercharged internal combustion engine in which the second shut-off element is infinitely variable are advantageous.

In particular, the configuration of the second shut-off element as a continuously variable valve allows the exact dosage of the recirculated into the deactivated cylinder exhaust gas amount; Similar to the setting of the recirculation rate of an exhaust gas recirculation by means of EGR valve. The dimensioning of the recirculated exhaust gas quantity can be specific to the operating point, in particular with regard to the lowest possible charge exchange losses.

Embodiments of the supercharged internal combustion engine in which the first shut-off element and / or the third shut-off element can be switched in two stages are advantageous.

The first shut-off is to block only the second flood during the partial shutdown and release after completion of the partial shutdown again, which is why a two-stage switchable shut-off principle is sufficient. The same applies to the arranged in the intake of a switchable cylinder third shut-off, which obstruct the intake of a deactivated cylinder and should release after completion of the partial shutdown again.

Embodiments of the internal combustion engine in which the first shut-off element and / or the second shut-off element and / or the third shut-off element is a valve or a pivotable flap or a throttle flap are advantageous.

The shut-off elements can be controlled electrically, hydraulically, pneumatically, mechanically or magnetically, preferably by means of motor control.

Advantageous embodiments of the supercharged internal combustion engine, in which the first shut-off element is a translationally displaceable element, d. H. a slider is.

Embodiments of the supercharged internal combustion engine in which at least one exhaust aftertreatment system is provided in the exhaust gas removal system are advantageous; For example, an oxidation catalyst, a three-way catalyst, a storage catalyst, a selective catalyst and / or a particulate filter.

In supercharged 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.

In order to obtain the pressure pulses of the Vorlassstöße for the purpose of shock charging at partial shutdown as far as possible, it is expedient to group the cylinder in a suitable manner or to guide the exhaust pipes together in a suitable manner, so that a mutual influence of the cylinder of a group is avoided. In a cylinder head with four cylinders arranged in series, it is advantageous in this regard, two cylinders, which have a firing interval of 360 ° KW, each to form a cylinder group together. If, for example, the ignition in the cylinders is initiated according to the ignition sequence 1-2-4-3 or according to the ignition sequence 1-3-4-2, it is advantageous for the outer cylinders to be a first group and the inner cylinders to be a second group to get together.

Advantageous embodiments of the supercharged internal combustion engine, in which an exhaust gas recirculation is provided, which includes a 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, and with increasing exhaust gas recirculation rate, the nitrogen oxide emissions can be significantly reduced. 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 recirculated exhaust gas and m _fresh air refers to the supplied and guided by the compressor and compressed fresh air. 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 valve for adjusting the recirculated exhaust gas quantity is arranged in the line of the exhaust gas recirculation are advantageous.

Embodiments of the supercharged internal combustion engine in which the line of exhaust gas recirculation branches off the exhaust gas removal system upstream of the turbine of the at least one exhaust gas turbocharger and opens into the intake system downstream of the compressor of the at least one exhaust gas turbocharger are advantageous.

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 particle filter must be supplied, since contamination of 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, whereby the charge pressure ratio also decreases, which is equivalent to a smaller charge air flow. 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 opens upstream of the compressor in the intake system.

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

Since exhaust gas is passed through the compressor as part of the low-pressure EGR, it must first be subjected to exhaust gas aftertreatment, in particular in the particulate filter. Deposits in the compressor, which change the geometry of the compressor, in particular the flow cross-sections, and in this way deteriorate the efficiency of the compressor are to be avoided.

Advantageous embodiments of the supercharged internal combustion engine, in which each cylinder is equipped for introducing fuel with a direct injection.

Embodiments in which each cylinder is equipped with an injection nozzle for the purpose of direct injection are advantageous.

The fuel supply can be deactivated faster and more reliable for the purpose of partial shutdown in direct-injection internal combustion engines as in internal combustion engines with intake manifold injection, in which fuel residues in the intake manifold can lead to unwanted burns in the deactivated cylinder.

Nevertheless, embodiments of the internal combustion engine may be advantageous in which for the purpose of a fuel supply, a port injection is provided.

The second sub-task on which the invention is based, namely to disclose a method for operating a supercharged internal combustion engine of the type described above, is achieved by a method which is characterized in that the first shut-off element is transferred to the first working position as part of a partial shutdown.

What has already been said for the internal combustion engine according to the invention also applies to the method according to the invention, which is why at this point in general reference is made to the statements made above with regard to the supercharged internal combustion engine. The various internal combustion engines sometimes require different process variants.

In an advantageous process variants in which is at least connected in a switchable cylinders of the second group in dependence on the load T of the engine, in such a way that this at least one switchable cylinder falls below a predetermined load T _down is switched off and on exceeding a predetermined load T _{up is} switched on.

The prescribed for falling below or exceeding limit loads T _down and T _up can be the same size, but also different sizes. When the internal combustion engine is in operation, the cylinders of the first cylinder group are constantly in operation. There is a switching of second cylinder group, ie a connection or disconnection of this second group.

Advantageous are process variants in which the fuel supply of the at least one switchable cylinder is deactivated when switched off. There are advantages in terms of fuel consumption and pollutant emissions, which supports the goal of partial shutdown, namely to reduce fuel consumption and improve efficiency. In self-igniting internal combustion engines, it may even be necessary to deactivate the fuel supply in order to reliably prevent ignition of the mixture in the cylinder.

Advantageous are process variants in which the at least one cylinder in operation is ignited by means of autoignition.

The above process variant relates to methods in which the combustion is initiated by means of auto-ignition, and thus also on working methods, such as are commonly used in diesel engines.

It is also possible to use a hybrid combustion method with auto-ignition for operating a gasoline engine, for example the so-called HCCI method, which is also referred to as a space ignition method or as a CAI method. This method is based on a controlled auto-ignition of the fuel supplied to the cylinder. Here, the fuel - as in a diesel engine - under excess air, so superstoichiometric, burned. The lean-burn gasoline engine has comparatively low nitrogen oxide emissions due to the low combustion temperatures and also no soot emissions due to the lean mixture. In addition, the HCCI process leads to a high thermal efficiency. The fuel can be introduced both directly into the cylinder and into the intake manifold.

Embodiments of the method in which the predefinable load T _down and / or T _up is dependent on the rotational speed n of the internal combustion engine are advantageous. Then there is not just a concrete load whose falling below or exceeding is switched independent of the speed n. Rather, speed-dependent procedure and an area defined in the map, is switched off in the part.

In principle, further operating parameters of the internal combustion engine can be used as a criterion for a partial shutdown, for example the engine temperature or the coolant temperature after a cold start of the internal combustion engine.

Advantageous are process variants in which each cylinder is equipped to initiate a spark ignition with an ignition device, wherein the ignition device of the at least one switchable cylinder is deactivated at shutdown.

The above method variant relates to the application of the method in a spark-ignited internal combustion engine, for example a direct-injection spark-ignition engine, the cylinders of which are each equipped with an ignition device for initiating spark ignition.

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

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

1b schematically in half section along the axis of rotation of the impeller the basic structure of a twin-flow turbine of a first embodiment of the supercharged internal combustion engine with located in the second working position first shut-off, and

1c schematically cut in half section along the axis of rotation of the impeller in 1b shown turbine with located in the first working position first shut-off.

1a schematically shows a first embodiment of the supercharged internal combustion engine 13 , It is a four-cylinder in-line engine 13 in which the four cylinders 1 . 2 . 3 . 4 along the longitudinal axis of the cylinder head, ie in series, are arranged.

Every cylinder 1 . 2 . 3 . 4 has a suction line 5a . 5b for supplying charge air via intake system 6 and an exhaust pipe 7a . 7b for removing the exhaust gases via exhaust gas removal system 8th ,

The internal combustion engine 13 is for the purpose of charging with an exhaust gas turbocharger 12 equipped, with the turbine 12a in the exhaust system 8th and the compressor 12b in the total intake pipe 6a of the intake system 6 are arranged. That of the internal combustion engine 13 supplied fresh air is in the compressor 12b compressed, including the enthalpy of the exhaust gas flow in the turbine 12a is being used. The turbine 12a is a twin-flow turbine 12a in the form of a twin-flow turbine 12A , Downstream of the turbine 12a is an exhaust aftertreatment system 16 intended.

The internal combustion engine 13 is also with an exhaust gas recirculation 15 equipped with a high-pressure EGR. For this purpose, a line branches 15a to recirculate exhaust gas upstream of the turbine 12a from the exhaust system 8th and discharges downstream of the compressor 12b into the intake system 6 one. In the line 15a the exhaust gas recirculation 15 is a valve 14 arranged to adjust the amount of recirculated exhaust gas.

The four cylinders 1 . 2 . 3 . 4 are configured and form two groups with two cylinders each 1 . 2 . 3 . 4 , where the two outer cylinders 1 . 4 form a first group whose cylinder 1 . 4 even with partial shutdown of the internal combustion engine 13 are in operation, and 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.

In the intake pipes 5b the two inner cylinders 2 . 3 are as third shut-off elements 9 serving flaps 9 provided, which the suction lines 5b for supplying charge air via intake system 6 release when the inner cylinder 2 . 3 are switched on, or block if the two inner cylinder 2 . 3 for the purpose of partial shutdown of the internal combustion engine 13 are switched off or are.

The exhaust pipes 7a . 7b the cylinder 1 . 2 . 3 . 4 each cylinder group lead to the formation of an exhaust manifold each to an overall exhaust line 7A . 7B together. The two total exhaust pipes 7A . 7B are with the twin-bladed turbine 12a connected, each with an overall exhaust line 7A . 7B into a flood 17A . 17B the turbine 12a flows (see also 1b and 1c ).

In a first working position of the turbine 12a becomes the second tide associated with the second cylinder group 17B locked, ie from the impeller 19 separated, and with a return line 10a connected, the return line 10a into the intake pipes 5b the two load-dependent switchable cylinder 2 . 3 opens. In a second working position of the turbine 12a will be the second flood 17B released, ie with the impeller 19 connected, and at the same time from the return line 10a separated.

The return line 10a is used during partial shutdown exhaust into the deactivated cylinder 2 . 3 initiate. One in the exhaust gas recirculation system 10 provided second shut-off 11 serves the dosage of the thereby introduced recirculated exhaust gas amount. The return line 10a can during the partial shutdown for a pressure equalization between the inlet side 6 and the outlet side 8th the deactivated cylinder 2 . 3 ensure the charge cycle losses of these cylinders 2 . 3 be reduced during partial shutdown.

The 1b and 1c show schematically in half section - cut along the axis of rotation 19a of the impeller 19 - The basic structure of a twin-flow turbine 12a a first embodiment of the supercharged internal combustion engine, wherein 1b the turbine 12a with the first shut-off element 20 in the second working position and 1c the turbine 12a with the first shut-off element 20 in the first working position shows.

In the in the 1b and 1c illustrated turbine 12a it is a twin-flow turbine 12A , which is characterized in that the two floods 17A . 17B are arranged side by side and the impeller 19 at least in sections, to include equal radii. The two floods 17A . 17B the twin-stream turbine 12A are - at least in the illustrated half sections - radially equidistant from the shaft 19a the turbine 12a in the case 18 arranged.

The housing wall 18a of the turbine housing 18 separates the two floods 17A . 17B from each other until shortly before entering the impeller 19 , The impeller-side free end of the housing wall 18a thus has a distance from the impeller 19 and forms a connection in this way 18b between the two floods 17A . 17B with out.

The first shut-off element 20 is at the wheel end of the second tide 17B arranged, blocks this connection 18b in the first working position (see 1c ) and gives the connection 18b free again in the second working position (see 1b ).

At the same time, the first shut-off element connects 20 in the first working position the second flood 17B with a return line 10a . 21a (please refer 1c ) and separates the second flood in the second working position 17B again from this return line 10a . 21a (please refer 1b ).

The first shut-off element 20 is as a slider 20a trained and is from the first working position (see 1c ) in the second working position (see 1b ) or vice versa by translational displacement (see double arrow).

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

5a

Intake line of a cylinder of the first group

5b

Intake line of a cylinder of the second group

6

Intake system, inlet side

6a

Gesamtansaugleitung

7a

Exhaust pipe of a cylinder of the first group

7A

Total exhaust line of the first cylinder group

7b

Exhaust pipe of a cylinder of the second group, d. H. a switchable cylinder

7B

Total exhaust gas line of the second cylinder group

8th

Exhaust system, exhaust side

9

third shut-off element, flap

10

Exhaust gas recirculation system

10a

Return line

11

second shut-off element, valve

12

turbocharger

12a

turbine

12A

Twin-flow turbine

12b

compressor

13

Internal combustion engine, four-cylinder in-line engine

14

AGR valve

15

Exhaust gas recirculation

15a

management

16

aftertreatment system

17A

first tide

17B

second tide

18

turbine housing

18a

housing

18b

connection

19

Wheel

19a

Shaft, axis of rotation of the impeller

20

first shut-off element

20a

pusher

21a

Return line

n

Speed of the internal combustion engine

T

load

T _down

predefinable load for falling below a load

T _{max, n}

maximum load at a given speed n

T _up

predefinable load for exceeding a load

Claims (17)

Charged internal combustion engine ( 13 ) with at least two cylinders ( 1 . 2 . 3 . 4 ), in which - each cylinder ( 1 . 2 . 3 . 4 ) has at least one outlet opening, to which an exhaust pipe ( 7a . 7b ) for discharging the exhaust gases via Abgasabführsystem ( 8th ), - each cylinder ( 1 . 2 . 3 . 4 ) has at least one inlet opening, to which a suction line ( 5a . 5b ) for supplying charge air via intake system ( 6 ), - at least two 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 ( 13 ) operating cylinder ( 1 . 4 ) and the at least one cylinder ( 2 . 3 ) of a second group as a load-dependent switchable cylinder ( 2 . 3 ), - at least one exhaust gas recirculation ( 10 . 15 ), and - at least one exhaust gas turbocharger ( 12 ) is provided, the one in Abgasabführsystem ( 8th ) arranged turbine ( 12a ) and one in the intake system ( 6 ) arranged compressors ( 12b ), characterized in that - the exhaust pipes ( 7a . 7b ) the cylinder ( 1 . 2 . 3 . 4 ) each cylinder group with the formation of an exhaust manifold each to a total exhaust gas line ( 7A . 7B ), and - the two total exhaust gas lines ( 7A . 7B ) with a twin-flow turbine ( 12a ), which at least one in a turbine housing ( 18 ) on a rotatable shaft ( 19a ) stored impeller ( 19 ), are connected in the way that in each case a total exhaust gas line ( 7A . 7B ) with one of the two inlet openings of the turbine ( 12a ), wherein at each entrance a flood ( 17A . 17B ) of the turbine ( 12a ) and a first shut-off element ( 20 ) is provided, which in a first working position of the second cylinder group associated second flood ( 17B ) and from the at least one impeller ( 19 ) separates and in a second working position this second flood ( 17B ) and with the at least one impeller ( 19 ) connects. Charged internal combustion engine ( 13 ) according to claim 1, characterized in that the first shut-off element ( 20 ) at the impeller end of the second tide ( 17B ) is provided. Charged internal combustion engine ( 13 ) according to claim 1 or 2, characterized in that the two floods ( 17A . 17B ) in the turbine housing ( 18 ) by means of housing wall ( 18a ) are separated from each other, wherein the housing wall ( 18a ) impeller-side spaced to the at least one impeller ( 19 ) ends and in this way at its impeller-side end a connection ( 18b ) between the two floods ( 17A . 17B ) with trains. Charged internal combustion engine ( 13 ) according to claim 3, characterized in that the first shut-off element ( 20 ) at the impeller end of the second tide ( 17B ) is provided and the connection ( 18b ) locked in the first working position and releases in the second working position. Charged internal combustion engine ( 13 ) according to one of the preceding claims, characterized in that the first shut-off element ( 20 ) in the first working position the second flood ( 17B ) with a return line ( 10a . 21a ) and in the second working position the second flood ( 17B ) from this return line ( 10a . 21a ), wherein the return line ( 10a ) into the suction line ( 5b ) of the at least one load-dependent switchable cylinder ( 2 . 3 ). Charged internal combustion engine ( 13 ) according to claim 5, characterized in that in the return line ( 10a ) a second shut-off element ( 11 ) is provided. Charged internal combustion engine ( 13 ) according to claim 5 or 6, characterized in that in the suction line ( 5b ) of the at least one load-dependent switchable cylinder ( 2 . 3 ) a third shut-off element ( 9 ) is provided, which the suction line ( 5b ) for supplying charge air with the cylinder switched on ( 2 . 3 ) and with deactivated cylinder ( 2 . 3 ), and the return line ( 10a ) downstream of this third shut-off element ( 9 ) into the suction line ( 5b ) of the at least one load-dependent switchable cylinder ( 2 . 3 ). Charged internal combustion engine ( 13 ) according to claim 6 or 7, characterized in that the second shut-off element ( 11 ) is infinitely adjustable. Charged internal combustion engine ( 13 ) according to one of the preceding claims, characterized in that the first shut-off element ( 20 ) and / or the third shut-off element ( 9 ) are switchable in two stages. Charged internal combustion engine ( 13 ) according to one of the preceding claims, characterized in that the first shut-off element ( 20 ) a translationally displaceable element ( 20a ). Charged internal combustion engine ( 13 ) according to one of the preceding claims, characterized in that at least one exhaust aftertreatment system ( 16 ) in the exhaust gas removal system ( 8th ) is provided. Charged internal combustion engine ( 13 ) 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. Charged internal combustion engine ( 13 ) according to one of the preceding claims, characterized in that an exhaust gas recirculation ( 15 ), which is a line ( 15a ), which from the Abgasabführsystem ( 8th ) branches off and into the intake system ( 6 ). Charged internal combustion engine ( 13 ) according to claim 13, characterized in that in the line ( 15a ) of exhaust gas recirculation ( 15 ) a valve ( 14 ) is arranged to adjust the amount of recirculated exhaust gas. Charged internal combustion engine ( 13 ) according to claim 13 or 14, characterized in that the line ( 15a ) of exhaust gas recirculation ( 15 ) upstream of the turbine ( 12a ) of the at least one exhaust gas turbocharger ( 12 ) from the exhaust gas removal system ( 8th ) branches off and downstream of the compressor ( 12b ) of the at least one exhaust gas turbocharger ( 12 ) into the intake system ( 6 ). Method for operating a supercharged internal combustion engine ( 13 ) according to one of the preceding claims, characterized in that the first shut-off element ( 20 ) is transferred in the context of a partial shutdown in the first working position. A method according to claim 16, characterized in that the at least one switchable cylinder ( 2 . 3 ) of the second group as a function of the load T of the internal combustion engine ( 13 ) is switched in such a way that this at least one switchable cylinder ( 2 . 3 ) Is switched off on falling below a predeterminable load and T _down is activated on exceeding a predetermined load T _up.

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