DE102014200572A1 - Supercharged internal combustion engine with at least one exhaust gas turbocharger and method for operating such an internal combustion engine - Google Patents

Abstract

The invention relates to a supercharged internal combustion engine (1) having an intake system (11), an exhaust gas removal system (5), at least one exhaust gas turbocharger (8), in which a compressor (8b) in the intake system (11) and a turbine (8a) in the exhaust gas discharge system (8). 5) are arranged on a rotatable shaft, and at least one cylinder head (2) having at least two cylinders (3) arranged in series along a longitudinal axis (10a) of the cylinder head (2), each cylinder (3) having at least two outlet openings (4a, 4b) for discharging the exhaust gases, of which at least one is designed as connectable outlet opening (4a), and to each outlet opening (4a, 4b) an exhaust pipe (5a, 5b) connects, in which - an exhaust gas recirculation is provided with a return line , which branches off from the exhaust gas discharge system (5) and opens into the intake system (11), - the exhaust pipes (5a) of the switchable outlet openings (4a) of at least two cylinders (3) to form a first exhaust manifold (6a) to a first total exhaust line (7a) merge, and - merge the exhaust pipes (5b) of the other outlet openings (4b) of the at least two cylinders (3) to form a second exhaust manifold (6b) to a second total exhaust line (7b) , wherein - the two total exhaust pipes (7a, 7b) with a twin-bladed turbine (9), which comprises at least one impeller mounted in a turbine housing on the rotatable shaft, are connected in such a way that in each case an overall exhaust line (7a, 7b) with a the two floods of the turbine (8a, 9) is connected, wherein the two floods in the direction of the at least one impeller are at least partially separated from each other by means of housing wall.

Description

• – eine Abgasrückführung vorgesehen ist mit einer Rückführleitung, die vom Abgasabführsystem abzweigt und in das Ansaugsystem mündet,
• – die Abgasleitungen der zuschaltbaren Auslassöffnungen von mindestens zwei Zylindern unter Ausbildung eines ersten Abgaskrümmers zu einer ersten Gesamtabgasleitung zusammenführen, und
• – die Abgasleitungen der anderen Auslassöffnungen der mindestens zwei Zylinder unter Ausbildung eines zweiten Abgaskrümmers zu einer zweiten Gesamtabgasleitung zusammenführen.

The invention relates to a supercharged internal combustion engine with an intake system for supplying the internal combustion engine with charge air, a Abgasabführsystem for discharging the exhaust gases, at least one exhaust gas turbocharger, in which a compressor in the intake system and a turbine in the exhaust system are arranged on a rotatable shaft, and at least one cylinder head at least two cylinders arranged in series along a longitudinal axis of the cylinder head, each cylinder having at least two outlet openings for discharging the exhaust gases, at least one of which is designed as a connectable outlet opening, and an exhaust pipe adjoining each outlet opening, in which

• An exhaust gas recirculation is provided with a return line, which branches off from the exhaust gas removal system and opens into the intake system,
• - Merge the exhaust gas lines of the switchable outlet openings of at least two cylinders to form a first exhaust manifold to a first total exhaust gas line, and
• - Merge the exhaust pipes of the other outlet openings of the at least two cylinders to form a second exhaust manifold to a second total exhaust line.

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

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

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

As part of the charge exchange, the exhaust of the combustion gases via the outlet openings of the cylinder and the filling of the combustion chambers, d. H. the intake of the fresh mixture or the charge air via the inlet openings. It is the task of the valve drive to open or close the inlet and outlet openings in good time, with the aim of achieving rapid release of flow cross sections which are as large as possible, in order to keep the throttling losses in the inflowing and outflowing gas flows low and to ensure the best possible filling of the combustion chambers or combustion chambers an effective, d. H. To ensure complete removal of the exhaust gases. Therefore, according to the prior art, the cylinders are often equipped with two or more inlet and outlet ports. Also, the at least two cylinders of the internal combustion engine, which is the subject of the present invention, are equipped with at least two outlet openings.

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

Downstream of the manifold, the exhaust gases in the present case for the purpose of charging the internal combustion engine of the turbine of at least one exhaust gas turbocharger supplied and optionally one or more systems for exhaust aftertreatment.

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

An exhaust gas turbocharger includes a compressor and a turbine disposed on the same shaft. The hot exhaust stream is supplied to the turbine and relaxes with energy release in the turbine, causing the shaft to rotate. From the exhaust flow to the turbine and Finally, energy delivered to the shaft is used to drive the compressor also located on the shaft. The compressor conveys and compresses the charge air supplied to it, whereby charging of the at least two cylinders is achieved. Optionally, a charge air cooling is provided, with which the compressed combustion air is cooled before entering the cylinder.

The charge is used primarily to increase the performance of the internal combustion engine. The air required for the combustion process is compressed, which allows each cylinder per working cycle, a larger air mass can be supplied. As a result, the fuel mass and thus the medium pressure can be increased. The charge is a suitable means to increase the capacity of an internal combustion engine with unchanged displacement or to reduce the displacement at the same power. In any case, the charge leads to an increase in engine capacity and a lower power mass. At the same vehicle boundary conditions, the load collective can thus be shifted to higher loads in which the specific fuel consumption is lower.

The design of the exhaust turbocharger often causes difficulties, in principle, a noticeable increase in performance in all speed ranges is sought. In the prior art, however, a torque drop is observed when falling below a certain speed. This torque drop becomes understandable if it is taken into account that the boost pressure ratio depends on the turbine pressure ratio. For example, if the engine speed is reduced, this leads to a smaller exhaust gas mass flow and thus to a smaller turbine pressure ratio. As a result, the boost pressure ratio and the charge pressure also decrease at lower speeds, which is equivalent to a torque drop.

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

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

For example, by a small design of the turbine cross-section and simultaneous Abgasabblasung. Such a turbine is also referred to as a waste gate turbine. If the exhaust gas mass flow exceeds a critical size, part of the exhaust gas flow is conducted past the turbine by means of a bypass line as part of the so-called exhaust gas blow-off. This approach has the disadvantage that the charging behavior at higher speeds or larger amounts of exhaust gas is insufficient.

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

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

The downsizing is continued by a multi-stage turbocharger charge. Furthermore, the response of such a supercharged internal combustion engine is significantly improved over a comparable internal combustion engine with single-stage charging, since the smaller high-pressure stage less sluggish, because the running gear of a smaller sized exhaust gas turbocharger can accelerate faster.

The torque characteristic of a supercharged internal combustion engine may be further characterized by a plurality of turbochargers arranged in parallel, i. H. be improved by a plurality of parallel turbines with a smaller turbine cross-section, with turbines are switched successively with increasing exhaust gas.

Basically, it is endeavored to arrange the turbine of an exhaust gas turbocharger as close as possible to the exhaust ports of the cylinder in order to be able to optimally use the exhaust enthalpy of the hot exhaust gases, which is largely determined by the exhaust gas pressure and the exhaust gas temperature, in this way, and a fast response Turbine and thus a turbocharger. In this connection, therefore, it is also fundamentally desired to minimize the thermal inertia and the volume of the conduit system between the outlet openings of the cylinders and the turbine, which can be achieved by reducing the mass and the length of the exhaust pipes.

In order to improve the torque characteristics of the internal combustion engine according to the invention, the exhaust pipes of at least two cylinders are grouped together in such a way that the exhaust pipes of the switchable exhaust ports and the exhaust pipes of the other exhaust ports are combined to form an exhaust gas manifold to form an exhaust pipe.

Concepts are known from the prior art in which the exhaust lines of the switchable outlet openings lead to the turbine of a first exhaust gas turbocharger and the exhaust pipes of the other outlet openings to the turbine of a second exhaust gas turbocharger. The switchable outlet openings associated with the first turbine is thus designed as a switchable turbine. Only with larger amounts of exhaust gas, the switchable outlet openings are opened in the context of the charge cycle, thereby activating the switchable turbine, d. H. Exhaust gas is applied.

Compared to concepts in which a single contiguous exhaust pipe system is provided upstream of the two turbines, the grouping described above, that is to say, increases. H. the use of two separate exhaust manifolds, the operating behavior of the internal combustion engine, especially for small exhaust gas flows, also because the line volume upstream of the second turbine continuously flowed through by exhaust gas is reduced by this measure, which at low loads or speeds, d. H. small amounts of exhaust gas, is advantageous and in particular improves the response.

But there are also disadvantages. The speed of the switchable turbine drops sharply when it is deactivated, so that when it is switched on again, the rotor of this turbine must first be accelerated in order to be able to generate and provide the desired boost pressure on the compressor side. The response deteriorates.

In order to ensure a minimum speed of the switchable turbine, the switchable turbine could be supplied with a small exhaust gas flow even when the exhaust ports are switched off. For this purpose, a corresponding line would have to connect the second exhaust manifold to the first turbine using additional shut-off elements, but this would disadvantageously increase the complexity and space requirements of the exhaust pipe system upstream of the turbines. In addition, a connection between the two exhaust manifolds would be created by the line and the grouping described above be canceled. The effects achieved by using two separate exhaust manifolds would at least be mitigated.

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 whose exhaust gas turbocharging is further improved.

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

• – eine Abgasrückführung vorgesehen ist mit einer Rückführleitung, die vom Abgasabführsystem abzweigt und in das Ansaugsystem mündet,
• – die Abgasleitungen der zuschaltbaren Auslassöffnungen von mindestens zwei Zylindern unter Ausbildung eines ersten Abgaskrümmers zu einer ersten Gesamtabgasleitung zusammenführen, und
• – die Abgasleitungen der anderen Auslassöffnungen der mindestens zwei Zylinder unter Ausbildung eines zweiten Abgaskrümmers zu einer zweiten Gesamtabgasleitung zusammenführen, und die dadurch gekennzeichnet ist, dass
• – die beiden Gesamtabgasleitungen mit einer zweiflutigen Turbine, die mindestens ein in einem Turbinengehäuse auf der drehbaren Welle gelagertes Laufrad umfasst, in der Art verbunden sind, dass jeweils eine Gesamtabgasleitung mit einer der zwei Fluten der Turbine verbunden ist, wobei die zwei Fluten in Richtung des mindestens einen Laufrades zumindest abschnittsweise – in Fortsetzung der Gesamtabgasleitungen – mittels Gehäusewandung voneinander getrennt sind.

The first sub-task is solved by a supercharged internal combustion engine with an intake system for supplying the internal combustion engine with charge air, a Abgasabführsystem for discharging the exhaust gases, at least one exhaust gas turbocharger, in which a compressor in the intake system and a turbine in the exhaust system are arranged on a rotatable shaft, and at least a cylinder head having at least two cylinders arranged in series along a longitudinal axis of the cylinder head, each cylinder having at least two exhaust ports for discharging the exhaust gases, at least one of which is designed as a connectable exhaust port and an exhaust pipe adjoining each exhaust port, in which

• An exhaust gas recirculation is provided with a return line, which branches off from the exhaust gas removal system and opens into the intake system,
• - Merge the exhaust gas lines of the switchable outlet openings of at least two cylinders to form a first exhaust manifold to a first total exhaust gas line, and
• - Merge the exhaust pipes of the other outlet openings of the at least two cylinders to form a second exhaust manifold to a second total exhaust line, and which is characterized in that
• - The two total exhaust pipes with a double-flow turbine, the at least one in a Turbine housing mounted on the rotatable shaft impeller, are connected in such a way that in each case an overall exhaust line is connected to one of the two floods of the turbine, the two floods in the direction of at least one impeller at least partially - in continuation of the total exhaust gas lines - by housing wall from each other are separated.

According to the invention, a twin-flow turbine is used instead of two turbines. This has several advantages over the prior art.

As a result of the omission of the second exhaust gas turbocharger there are cost advantages. Compared to conventional concepts of the exhaust gas turbocharger, the space requirement decreases, whereby a compact design of the internal combustion engine and a dense packaging of the entire drive unit in the engine compartment are possible, and not only due to the omission of the second exhaust gas turbocharger. Rather, eliminates the need to provide an additional line to a switchable turbine even with deactivation, d. H. with exhaust ports switched off, to supply exhaust gas from the second exhaust manifold and to ensure a minimum speed of the turbine.

If the switchable outlet openings are deactivated, according to the invention only the first flow of the twin-flow turbine connected to the switchable exhaust ports via the first manifold and the first exhaust gas line is not supplied with exhaust gas, while the other second flow, which is supplied with exhaust gas from the second manifold, the at least one placed on the rotating shaft mounted impeller in rotation and thus maintains the speed of the shaft.

The problem described in connection with the prior art concerning the maintenance of a minimum speed of the switchable turbine is eliminated and thus the need for a connecting line between the exhaust manifolds. According to the invention, the grouping is actually maintained and there are two strictly and continuously separate exhaust manifolds. The resulting effects are thus fully effective.

Thus, the first object of the invention is solved, namely provided a supercharged internal combustion engine according to the preamble of claim 1, the exhaust gas turbocharging is further improved.

An internal combustion engine according to the invention may also have two cylinder heads.

According to the invention, the exhaust pipes of all the cylinders of a cylinder head need not merge into two total exhaust pipes, but only the exhaust pipes of at least two cylinders are connected in the manner described.

However, embodiments in which the exhaust gas lines of all the cylinders of the at least one cylinder head merge to form two total exhaust gas lines are particularly advantageous.

The internal combustion engine is equipped with an exhaust gas recirculation, which comprises a return line which - preferably upstream of the turbine - branches off from the Abgasabführsystem and opens into the intake system, preferably downstream of the compressor.

To meet future limits for nitrogen oxide emissions, an exhaust gas recirculation is increasingly used, ie the return of exhaust gases from the Abgasabführsystem in the intake system, in which the nitrogen oxide emissions can be significantly reduced with increasing exhaust gas recirculation rate. The exhaust gas recirculation rate x _{EGR is} determined as follows: x _AGR = m _EGR / (m _EGR + m _{fresh air} ), where m _AGR denotes the mass of recirculated exhaust gas and m _{fresh air} the charge air guided and compressed by the compressor.

Exhaust gas recirculation is also suitable for reducing emissions of unburned hydrocarbons in the partial load range.

In order to achieve a significant reduction in nitrogen oxide emissions, high exhaust gas recirculation rates are required, which can be on the order of x _EGR ≈ 60% to 70%.

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

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

Embodiments of the supercharged internal combustion engine in which the two Flooding - in continuation of the total exhaust gas lines - up to the at least one impeller by means of housing wall are separated.

In the present case, the housing wall separating the two floods does not terminate at the impeller side with the formation of a tongue spacing spaced apart from the at least one impeller, but reaches as far as the at least one impeller, as far as possible and permits rotation of the at least one impeller without interference. This ensures that the exhaust gas streams originating from the two manifolds are conducted separately from one another onto the impeller and unite and mix only downstream of the impeller or when the impeller flows through it. The degree of separation of the floods is maximized and an interaction between the floods, in particular an overflow, is largely prevented.

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

In the present case, the exhaust gas lines of both the switchable outlet openings and the other outlet openings are each combined to form an integrated exhaust manifold within the cylinder head to form an overall exhaust gas line.

As already mentioned, it is fundamentally endeavored to arrange the turbine of an exhaust-gas turbocharger as close as possible to the outlet openings of the cylinders in order to keep the path of the hot exhaust gases to the turbine runner as short as possible and the line volume upstream of the turbine runner small. The most extensive integration of the exhaust pipes and the exhaust manifold in the cylinder head is purposeful.

The length of the exhaust pipes is reduced by integration into the cylinder head. On the one hand thereby the line volume, d. H. reduces the exhaust gas volume of the exhaust pipes upstream of a turbine, so that the response of this turbine is improved. On the other hand, the shortened exhaust pipes also lead to a lower thermal inertia of the exhaust system upstream of the turbine, so that the temperature of the exhaust gases is increased at the turbine inlet, which is why the enthalpy of the exhaust gases at the inlet of the turbine is higher. Optionally provided exhaust aftertreatment systems achieve a required minimum operating temperature faster.

The integration of the exhaust manifold in the cylinder head allows dense packaging of the drive unit and also has the advantage that can be participated in an optionally provided in the cylinder head liquid cooling, in the way that the manifold does not have to be made of thermally highly resilient and therefore costly materials ,

The integration of the exhaust manifold in the cylinder head also leads to a smaller number of components and thus to a reduction in costs, in particular the installation and deployment costs.

In internal combustion engines, in which the at least one cylinder head can be connected to a cylinder block at a mounting end, embodiments are advantageous in this context, which are characterized in that the one exhaust gas line is arranged on the side remote from the mounting end side of the other exhaust line.

With regard to the mounting end face, the two total exhaust gas lines are arranged at different heights. The two exhaust manifolds are at least partially superimposed, d. H. spaced apart in the direction of a cylinder longitudinal axis.

Embodiments of the supercharged internal combustion engine in which the two total exhaust gas lines are offset along the longitudinal axis of the cylinder head to form a distance Δ are advantageous.

The offset Δ allows a compact design of the cylinder head, d. H. a low cylinder head height, and at the same time ensures a sufficiently large distance of the total exhaust gas lines from each other. In this way, despite a compact design sufficient space between the entire exhaust gas lines in comparison to execution forms remain, in which the entire exhaust pipes along the cylinder head longitudinal axis have no offset. This also facilitates the arrangement of coolant channels in the cylinder head between the two total exhaust lines, if liquid cooling is to be provided.

Embodiments of the supercharged internal combustion engine in which the following applies for the distance Δ between the two total exhaust gas lines are: 0.5d≤Δ≤1.5d, where d denotes the diameter of an outlet opening.

Embodiments of the supercharged internal combustion engine in which the following applies to the distance Δ between the two total exhaust gas lines are advantageous: 10 mm ≦ Δ ≦ 50 mm.

Embodiments of the supercharged internal combustion engine in which the twin-flow turbine is a twin-flow turbine in which the two floods surround the at least one impeller arranged at least in sections next to one another on equally large radii are advantageous.

Also advantageous are embodiments of the supercharged internal combustion engine in which the twin-flow turbine is a double-flow turbine, in which the two floods - in a section perpendicular to the shaft of the at least one impeller - are arranged one above the other at least along an arcuate portion, the at least one impeller spirally Surround radii of different sizes and are each open along an arcuate segment to the at least one impeller out.

Embodiments of the supercharged internal combustion engine in which the twin-flow turbine is a radial turbine are advantageous. In a radial turbine, the flow of the blades takes place substantially radially. In the context of the present invention, essentially radial means that the velocity component in the radial direction is greater than the axial velocity component. In this case, the exhaust gas is fed to the at least one impeller often radially by means of spiral housing and directed to the at least one impeller, the outflow is often axial.

Advantageous embodiments of the supercharged internal combustion engine, in which the turbine is designed as a waste-gate turbine, wherein upstream of the turbine, a bypass line branches off from the second exhaust manifold and a shut-off element is provided in the bypass line. As soon as the exhaust gas mass flow exceeds a critical value, exhaust gas is guided past the turbine via the bypass line. For this purpose, a shut-off is to be provided in the bypass line.

Advantageous embodiments of the supercharged internal combustion engine, in which the turbine is designed as a waste-gate turbine, wherein upstream of the turbine, a bypass line branches off from the first exhaust manifold and a shut-off element is provided in the bypass line. As soon as the exhaust gas mass flow exceeds a critical value, exhaust gas is guided past the turbine via the bypass line. For this purpose, a shut-off element is provided in the bypass line.

Embodiments of the supercharged internal combustion engine in which the bypass line opens downstream of the turbine into the exhaust gas removal system are advantageous. This offers advantages in particular with regard to exhaust aftertreatment, since the entire exhaust gas can be subjected to a common aftertreatment.

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 intercooler lowers the air temperature and thus increases the density of the charge air, whereby the radiator to a better filling of the combustion chamber with charge air, d. H. contributes to a larger air mass. It is advantageous to provide the intercooler with a bypass line, which allows bypassing the radiator, especially in the warm-up phase.

The cylinder head of an internal combustion engine is basically a thermally and mechanically highly loaded component. The requirements for the cylinder head according to the invention are particularly high. It should be noted in this context that supercharged internal combustion engines are subject to particularly high thermal loads. With an integration of the exhaust manifold, the thermal load of the internal combustion engine or the cylinder head increases again, so that increased demands are placed on the cooling.

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

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

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

This includes, in particular, embodiments in which the at least one coolant jacket has an imaginary envelope, which is placed around the two overall exhaust lines, ie. H. Envelope passes, d. H. cuts.

In the area of the total exhaust gas lines, the cylinder head is subjected to particularly high thermal loads, since the two exhaust gas lines, in contrast to a cylinder-associated exhaust gas line, are exposed to larger amounts of exhaust gas. Ie. the absolute amount of exhaust gas that gives off heat to the cylinder head is comparatively large. On the other hand, the total exhaust gas lines are almost continuously exposed to hot exhaust gases, whereas a Exhaust pipe of a cylinder is only flowed through during the change of charge of the respective cylinder of hot exhaust gas.

Embodiments of the supercharged internal combustion engine in which the at least one cylinder head comprises three cylinders arranged in series along the longitudinal axis of the cylinder head are advantageous.

In the prior art, three-cylinder in-line engines are rarely combined with twin-jet turbines. The turbine is supplied with exhaust gas by means of a single exhaust manifold, wherein only in the turbine or in the turbine housing, a distribution of the exhaust gas takes place on both floods or the blocking of a flood or the cross-sectional change of a flood is performed. Problems arise in particular with regard to the durability of the adjusting device in the housing.

By contrast, the grouping of the exhaust pipes according to the invention permits the use of a twin-flow turbine without having to provide an adjusting device in the turbine housing, since both floods are supplied separately with exhaust gas. Compared to concepts in which the cylinders are grouped, for example in such a way that the outer cylinder form a first group and the inner forms the second group, resulting from the temporally uniform admission of the floods or at least one impeller with exhaust gas.

Embodiments of the supercharged internal combustion engine in which the at least one cylinder head comprises four cylinders arranged in series along the longitudinal axis of the cylinder head are also advantageous.

Advantageously, embodiments of the supercharged internal combustion engine, which are equipped to actuate the valves of the switchable outlet openings with a switchable valve train, for example, serving as a cam follower and located in the power flow plunger is designed as a switchable plunger.

The twin-flow turbine can be equipped with a variable turbine geometry, which is adjusted by adjusting to the respective operating point of the internal combustion engine.

The second sub-task on which the invention is based, namely a method for operating an internal combustion engine of the type described above, is achieved by a method in which the switchable outlet openings are deactivated as soon as the engine speed n _{mot of} the internal combustion engine falls below a predefinable engine speed n _{mot, down} ,

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

Also advantageous are process variants in which the deactivated switchable outlet openings are activated as soon as the exhaust gas quantity exceeds a predefinable amount of exhaust gas.

In the following the invention is based on two embodiments according to the 1a . 1b and 2 described in more detail. Hereby shows:

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

1b schematically a second embodiment of the internal combustion engine, and

2 in a perspective view of the sand cores integrated in the cylinder head exhaust pipes according to the first embodiment of the internal combustion engine.

1a schematically shows a first embodiment of the supercharged internal combustion engine 1 that with an exhaust gas turbocharger 8th Is provided. The turbocharger 8th includes a twin-flow turbine 8a . 9 and a compressor 8b , The hot exhaust gas relaxes in the turbine 8a . 9 under energy release. The compressor 8b compresses the charge air via the intake system 11 and plenum 12 the cylinders 3 is supplied, whereby a charge of the internal combustion engine 1 is reached. Downstream of the compressor 8b is a charge air cooler 13 in the intake pipe 11a intended. The intercooler 13 lowers the air temperature and thus increases the density of the charge air, which also causes the radiator 13 to a better filling of the cylinder 3 contributes with charge air.

At the in 1a illustrated internal combustion engine 1 it is a four-cylinder in-line engine 1a in which four cylinders 3 along the longitudinal axis 10a of the cylinder head 2 , ie in series, are arranged. Every cylinder 3 has two outlet openings 4a . 4b on, being attached to each outlet opening 4a . 4b an exhaust pipe 5a . 5b for removing the exhaust gases from the cylinder 3 followed.

One outlet each 4a every cylinder 3 is as a switchable outlet opening 4a formed, which is opened in the context of the charge change only when the associated valve train is activated and the speed n _mot exceeds a predetermined speed and the amount of exhaust gas exceeds a predetermined amount of exhaust gas. The exhaust pipes 5a the switchable outlet openings 4a all cylinders 3 lead to the formation of a first exhaust manifold 6a inside the cylinder head 2 (not shown) to a first overall exhaust line 7a together.

The exhaust pipes 5b the other outlet openings 4b all cylinders 3 lead to the formation of a second exhaust manifold 6b inside the cylinder head 2 (not shown) to a second total exhaust line 7b together.

The two total exhaust pipes 7a . 7b are with the twin-bladed turbine 8a . 9 the loader 8th connected, each with an overall exhaust line 7a . 7b with one of the two floods of the turbine 8a . 9 connected is. The turbine 8a . 9 is designed as a waste gate turbine. Upstream of the turbine 8a . 9 branches a bypass line 9a from the second exhaust manifold 6b from. One in the bypass line 9a provided shut-off 9b is used to set the amount of exhaust gas blown off. Exceeds the exhaust gas mass flow a predetermined amount of exhaust gas, exhaust gas via bypass line 9a at the turbine 8a . 9 past.

How out 1a can be seen, are the first exhaust manifold 6a and the second exhaust manifold 6b upstream of the turbine 8a . 9 separated from each other. The two floods of the turbine 8a . 9 are up to the impeller in continuation of the total exhaust pipes 7a . 7b also separated from each other by means of a housing wall (not shown).

1b schematically shows a second embodiment of the internal combustion engine 1 , It should only the differences to the in 1a Otherwise, reference will be made to FIG 1a , The same reference numerals have been used for the same components.

Unlike the in 1a The embodiment shown in FIG 1b illustrated internal combustion engine 1 around a three-cylinder in-line engine 1b in which three cylinders 3 along the longitudinal axis 10a of the cylinder head 2 are arranged.

2 shows a perspective view of the sand cores to form the integrated in the cylinder head exhaust pipes 5a . 5b . 7a . 7b according to the first embodiment of the internal combustion engine.

2 thus shows the system of integrated in the cylinder head exhaust pipes 5a . 5b . 7a . 7b or exhaust manifolds 6a . 6b , which is why the reference numbers for the exhaust pipes 5a . 5b . 7a . 7b and the exhaust manifold 6a . 6b are registered.

At the in 2 shown sand cores or exhaust manifolds 6a . 6b it is the exhaust pipes 4a . 4b . 7a . 7b the four cylinders 3 of the four-cylinder in-line engine according to 1a in which the cylinders 3 are arranged along the longitudinal axis of the cylinder head.

Each of the four cylinders 3 is with two outlet openings 4a . 4b fitted to each outlet 4a . 4b an exhaust pipe 5a . 5b followed.

The exhaust pipes 5a the switchable outlet openings 4a lead to the formation of a first integrated exhaust manifold 6a within the cylinder head to a first overall exhaust line 7a and the exhaust pipes 5b the other outlet openings 4b lead to the formation of a second integrated exhaust manifold 6b within the cylinder head to a second total exhaust line 7b together.

How out 2 As can be seen, the two total exhaust pipes 7a . 7b the integrated exhaust manifold 6a . 6b along the longitudinal axis of the cylinder head, ie also along a parallel 10 arranged offset to the longitudinal axis of the cylinder head to form a distance Δ, wherein the total exhaust gas line 7a of the first integrated exhaust manifold 6a on the side facing away from the mounting end side of the entire exhaust line 7b of the second integrated exhaust manifold 6b lies. Ie. the total exhaust pipes 7a . 7b lie one above the other, with the second total exhaust line 7b between the mounting end face and the first overall exhaust gas line 7a is arranged.

LIST OF REFERENCE NUMBERS

1

 charged internal combustion engine

1a

 Four-cylinder in-line engine

1b

 Three-cylinder engine

2

 cylinder head

3

 cylinder

4a

 switchable outlet opening

4b

 outlet

5

 Abgasabführsystem

5a

 exhaust pipe

5b

 exhaust pipe

6a

 first exhaust manifold

6b

 second exhaust manifold

7a

 first total exhaust gas line

7b

 second total exhaust line

8th

 turbocharger

8a

 Turbine of the exhaust gas turbocharger

8b

 Compressor of the exhaust gas turbocharger

9

 twin-flow turbine

9a

 Bypass line, blow-off line

9b

 shut-off

10

 Parallel to the longitudinal axis of the cylinder head

10a

 Longitudinal axis of the cylinder head

11

 intake system

11a

 suction

12

 plenum

13

 Intercooler

14

 Shut-off element, throttle element

d

 Diameter of an outlet opening

n _mot

 Speed of the internal combustion engine

n _{mot, down}

 predefinable speed for deactivating the switchable outlet openings

Δ

 Distance of the total exhaust gas lines along the longitudinal axis of the cylinder head

Claims (19)

Charged internal combustion engine ( 1 ) with an intake system ( 11 ) for supplying the internal combustion engine ( 1 ) with charge air, an exhaust gas removal system ( 5 ) for discharging the exhaust gases, at least one exhaust gas turbocharger ( 8th ), in which a compressor ( 8b ) in the intake system ( 11 ) and a turbine ( 8a ) in the exhaust gas removal system ( 5 ) are arranged on a rotatable shaft, and at least one cylinder head ( 2 ) with at least two along a longitudinal axis ( 10a ) of the cylinder head ( 2 ) arranged in series cylinders ( 3 ), each cylinder ( 3 ) at least two outlet openings ( 4a . 4b ) for discharging the exhaust gases, of which at least one as switchable outlet ( 4a ) is formed, and to each outlet opening ( 4a . 4b ) an exhaust pipe ( 5a . 5b ), in which - an exhaust gas recirculation is provided with a return line from the Abgasabführsystem ( 5 ) branches off and into the intake system ( 11 ), - the exhaust pipes ( 5a ) of the switchable outlet openings ( 4a ) of at least two cylinders ( 3 ) to form a first exhaust manifold ( 6a ) to a first overall exhaust gas line ( 7a ), and - the exhaust pipes ( 5b ) of the other outlet openings ( 4b ) the at least two cylinders ( 3 ) to form a second exhaust manifold ( 6b ) to a second total exhaust line ( 7b ), characterized in that - the two exhaust pipes ( 7a . 7b ) with a twin-flow turbine ( 9 ), which comprises at least one impeller mounted in a turbine housing on the rotatable shaft, are connected in such a way that in each case an overall exhaust gas line ( 7a . 7b ) with one of the two floods of the turbine ( 8a . 9 ), wherein the two floods in the direction of the at least one impeller at least in sections - in continuation of the total exhaust gas lines ( 7a . 7b ) - are separated by means of housing wall. Charged internal combustion engine ( 1 ) according to claim 1, characterized in that the two floods - in continuation of the total exhaust gas lines ( 7a . 7b ) - up to the at least one impeller by means of housing wall are separated from each other. Charged internal combustion engine ( 1 ) according to claim 1 or 2, characterized in that the exhaust pipes ( 5a . 5b ) the at least two cylinders ( 3 ) within the cylinder head ( 2 ) to the two total exhaust pipes ( 7a . 7b ) merge. Charged internal combustion engine ( 1 ) according to claim 3, wherein the at least one cylinder head ( 2 ) is connectable to a cylinder block at a mounting end face, characterized in that the one exhaust gas line ( 7a . 7b ) on the side facing away from the mounting end side of the other exhaust line ( 7a . 7b ) is arranged. Charged internal combustion engine ( 1 ) according to claim 4, characterized in that the two total exhaust gas lines ( 7a . 7b ) along the longitudinal axis ( 10a ) of the cylinder head ( 2 ) are arranged offset with the formation of a distance Δ. Charged internal combustion engine ( 1 ) according to claim 5, characterized in that for the distance Δ between the two total exhaust gas lines ( 7a . 7b ): 0.5 d ≦ Δ ≦ 1.5 d, where d is the diameter of an outlet opening ( 4a . 4b ) designated. Charged internal combustion engine ( 1 ) according to claim 5 or 6, characterized in that for the distance Δ between the two total exhaust gas lines ( 7a . 7b ): 10mm ≤ Δ ≤ 50mm. Charged internal combustion engine ( 1 ) according to one of the preceding claims, characterized in that the twin-flow turbine ( 8a . 9 ) is a twin-flow turbine, in which the two floods the at least one impeller at least partially adjacent to each other arranged on equal radii enclose. Charged internal combustion engine ( 1 ) according to one of claims 1 to 7, characterized characterized in that the twin-flow turbine ( 8a . 9 ) is a double-flow turbine, in which the two floods - in a section perpendicular to the shaft of the at least one impeller - at least along an arcuate portion are arranged one above the other, surround the at least one impeller spirally on different sized radii and each along a circular arc segment to the at least one impeller are open. Charged internal combustion engine ( 1 ) according to one of the preceding claims, characterized in that the twin-flow turbine ( 8a . 9 ) is a radial turbine. Charged internal combustion engine ( 1 ) according to one of the preceding claims, characterized in that the turbine ( 8a . 9 ) is designed as a waste-gate turbine, wherein upstream of the turbine ( 8a . 9 ) a bypass line ( 9a ) from the second exhaust manifold ( 6b ) branches off and a shut-off element ( 9b ) in the bypass line ( 9a ) is provided. Charged internal combustion engine ( 1 ) according to claim 11, characterized in that the bypass line ( 9a ) downstream of the turbine ( 8a . 9 ) into the exhaust gas removal system ( 5 ) opens. Charged internal combustion engine ( 1 ) according to one of the preceding claims, characterized in that downstream of the compressor ( 8b ) a charge air cooler ( 13 ) in the intake system ( 11 ) is arranged. Charged internal combustion engine ( 1 ) according to one of the preceding claims, characterized in that the at least one cylinder head ( 2 ) is equipped with at least one integrated coolant jacket. Charged internal combustion engine ( 1 ) according to claim 14, characterized in that the at least one coolant jacket also between the two total exhaust gas lines ( 7a . 7b ). Charged internal combustion engine ( 1 . 1b ) according to one of the preceding claims, characterized in that the at least one cylinder head ( 2 ) three along the longitudinal axis ( 10a ) of the cylinder head ( 2 ) cylinders arranged in series ( 3 ). Charged internal combustion engine ( 1 . 1a ) according to one of claims 1 to 15, characterized in that the at least one cylinder head ( 2 ) four along the longitudinal axis ( 10a ) of the cylinder head ( 2 ) cylinders arranged in series ( 3 ). Method for operating a supercharged internal combustion engine ( 1 ) according to one of the preceding claims, characterized in that the switchable outlet openings ( 4a ) are deactivated as soon as the engine speed n _{mot of} the internal combustion engine falls below a predefinable engine speed n _{mot, down} . A method according to claim 18, characterized in that the deactivated switchable outlet openings ( 4a ) are activated as soon as the amount of exhaust gas exceeds a predefinable amount of exhaust gas.

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