KR20110123286A - Internal combustion engine having sequential supercharging - Google Patents

Abstract

The present invention relates in particular to an internal combustion engine for automobiles having an electric drive train, in particular a combination of an electric motor and an internal combustion engine (hybrid engine), comprising at least one first exhaust gas turbocharger 30 and at least one second exhaust gas turbocharger ( 34, wherein the first exhaust gas turbocharger includes one or more first turbines 28 and one or more first compressors 36, and the second exhaust gas turbocharger includes one or more second turbines 32. ) And one or more second compressors 38, wherein the first turbines 28 and the second turbines 32 are arranged parallel to each other with respect to the exhaust gas flow in the exhaust gas pipes 22 of the internal combustion engine. The first compressor 36 and the second compressor 38 are arranged parallel to each other with respect to fresh air flow in the fresh air pipe 18 of the internal combustion engine, and at least one valve device 54 in the exhaust gas pipe 22. 64) operation of the internal combustion engine May selectively reduce and / or shut off the exhaust gas flow through the second turbine 32 and, at the same time, without limitation allow exhaust gas flow through the first turbine 28 to substantially reduce the first exhaust gas flow. Only the gas turbocharger 30 is arranged and designed to generate air pressure. To this end, one or more additional drive units 58 are arranged in addition to the second turbine 32 in the second exhaust gas turbocharger 34.

Description

INTERNAL COMBUSTION ENGINE HAVING SEQUENTIAL SUPERCHARGING}

The invention according to the preamble of claim 1, in particular as an internal combustion engine for automobiles, comprises at least one first exhaust gas turbocharger and at least one second exhaust gas turbocharger, wherein the first exhaust gas turbocharger is at least one. A first turbine and at least one first compressor, wherein the second exhaust gas turbocharger comprises at least one second turbine and at least one second compressor, wherein the first turbine and the second turbine are exhaust gases of an internal combustion engine. Disposed in parallel with one another in the conduit with respect to the exhaust gas flow, the first compressor and the second compressor being disposed in parallel with one another in connection with the fresh air flow in the fresh air conduit of the internal combustion engine, and at least one valve arrangement in the exhaust gas conduit Selectively reduces and / or blocks the exhaust gas flow through the second turbine in accordance with the operating state of the internal combustion engine and simultaneously The method may allow the exhaust gas flow flowing through the first turbine, without limitation, will substantially only the first exhaust gas turbocharger on an internal combustion engine that is arranged and designed to generate a pressure class. The invention also provides a method of operating an internal combustion engine, in accordance with the preamble of claim 14, wherein fresh air is compressed by each compressor in at least two turbochargers, each compressor being driven by a respective exhaust gas turbine. The second exhaust gas turbocharger is connected to the first exhaust gas turbocharger according to the operating point of the internal combustion engine, and before the connection, the second exhaust gas turbocharger is accelerated to a predetermined rotational speed. It is about.

In the so-called sequential supercharging of the internal combustion engine, two or more exhaust gas turbochargers (ATL) are provided, the turbochargers being provided with exhaust gases depending on the operating point by one or more additional switching elements on the exhaust gas side and / or on the fresh air side. Or air is supplied.

There are many possibilities for implementing sequential supercharging in internal combustion engines. These possibilities are all characterized by the use of two or more ATLs (exhaust gas turbochargers), in which the exhaust gases or air depending on the operating point by one or more additional switching members on the exhaust gas side and / or the fresh air side. Can be supplied.

Especially for the sequential supercharging of the Otto engine, only one ATL is operated at low engine speeds and the second ATL is connected at nominal output range without interruption of the compression operation of the first ATL, ie the first ATL The sequential concept, which contributes to a very large part of the supercharging operation, is suitable. By this concept, it is possible to optimally cover a very wide air flow demand in an Otto engine. When torque is required at the low air flow of the engine, since the total exhaust gas energy to be provided is provided to only one ATL, the ATL can be accelerated to its operating speed very quickly, thus providing very high air pressures very quickly. This can lead to higher response characteristics compared to conventional mono or twin turbo concepts. In the conventional mono turbo concept, the ATL must cover the rated power of the engine alone, so the ATL must be designed to be correspondingly large. This allows only a relatively slow response characteristic at low exhaust gas flows, such as at low engine speeds. In the conventional twin turbo concept, the provided exhaust gas energy is divided into two ATLs even at small exhaust gas flows at low engine speeds.

The sequential concept of an internal combustion engine is known, for example, from DE 10 2005 061 649 A1 and has two ATLs with a design very similar or identical to the conventional twin turbo design (pressure conditions, mass / volume flow capacity, etc.). Preferably, based on the ATL-design, which is optimal for conventional twin turbo operation, one ATL is chosen slightly smaller and the second ATL is chosen slightly larger. The supply of exhaust gas to the ATL is a sequential concept, so that when the exhaust gas flow is low (when the engine speed is low), the switchable pipe guides in the exhaust gas manifold provide the entire exhaust gas flow to only the smaller of the two ATLs. Is done. If the ATL reaches its maximum capacity and this is approximately medium engine speed, then a second, slightly larger ATL connection is made, and the sequential system operates similar to a conventional twin turbo system up to its rated output. Depending on the design of the system, the two ATLs divide the required flow at the rating point by 50% to 50%, or about 40% to 60% or about 45% to 55% to favor larger ATL.

Since the single ATL-operation in the sequential system described above cannot meet the airflow demand of the engine in the medium or high speed range, the connection of the second ATL is necessary. The transition to larger ATLs, where the first small ATL (so-called high stage) is cut off and the larger ATL (low stage) fully performs the supercharging operation, must be carried out relatively simply and many of these concepts already exist. The connection of the second ATL should be controlled more difficult. Switching to the second ATL as described above has the disadvantage that the second ATL must be designed very large in order for the second ATL to be able to supply air flow demand alone at the rated power point of the engine. This causes a corresponding package disadvantage. In addition, the availability of ATL for use in Otto engines is limited, in particular, to rated power greater than 200 kW and exhaust gas temperatures higher than 950 ° C. Against this background, the connection of the second ATL is more goal oriented in the Otto sequential concept. Another disadvantage of supercharging, which is adjusted in two stages in this way in the Otto engine, is that two ATLs are operated in series at a low speed range. Thus, the pressure conditions in the two turbines are increased and the engine must operate for very high exhaust gas back pressure, which results in poor residual gas flushing characteristics. Since the combustion method of the Otto engine reacts very critically with respect to its knocking limit on residual gas components remaining in the combustion chamber, this two-stage supercharging method is sometimes disadvantageous for the Otto engine.

As described above, for use in an auto engine, the exhaust gas is first supplied to only one ATL that is stress relief relative to the periphery and the second ATL is connected in parallel in the engine's revolution profile, ie the two ATL A sequential concept is preferred, which is stress relieved for or against the normal pressure loss of the exhaust gas system. The connection process is preferably through fully variable discharge valve control, but can also be via an exhaust gas valve that can withstand thermally high loads. The connection process of the second ATL is critical because the second ATL must be at the rotational speed of the first ATL in operation before the parallel connection. The connection process can be made without a rotating moment undershoot only when the suction tube pressure is kept constant. In ATL, the supply pressure directly depends on the number of revolutions of the ATL. From this, the condition that for the same size ATL, the first and second ATL should have the same rotation speed in order to prevent the rotation moment undershoot during the connection process. For ATLs of different sizes, similar speeds should be obtained for the same pressure conditions at the two ATLs (p2 / p1) before and after the turbine before the connection procedure. For run up of the second ATL, exhaust gas energy is no longer provided to the first ATL. That is, if a switchover from 1-ATL-operation to 2-ATL-operation is made without the rotation moment undershoot, the theoretical air pressure potential given by sequential supercharging cannot be used.

In DE 43 10 148 C2 a sequentially charged internal combustion engine is known, the first exhaust gas turbocharger always supplies the supply pressure and the second exhaust gas turbocharger is optionally connected. For a pulsation-free connection of the second exhaust turbocharger, if the second turbocharger does not contribute to the supply of air to the internal combustion engine, the pressure output of the compressor of the second exhaust turbocharger may be applied to the turbine of the second exhaust turbocharger. It is connected to the inlet. Thus, the second exhaust gas turbocharger is always maintained at the speed required for the air supply process of the internal combustion engine, so that when the second exhaust gas turbocharger is connected, the second exhaust gas turbocharger is discharged from the inlet of the turbine of the second exhaust gas turbocharger. 2, the pressure supply of the compressor of the exhaust gas turbocharger and the connection of the pressure output of the compressor of the second exhaust gas turbocharger and the combustion air supply line extending to the internal combustion engine immediately provide the necessary supply pressure without pressure fluctuations. Is given.

The problem of the present invention is to improve the internal combustion engine and method of the above scheme with respect to the connection of a second exhaust gas turbocharger of the sequential scheme.

The object is achieved by an internal combustion engine of the scheme with the features of claim 1 and a method of the scheme with the features of claim 14. Preferred embodiments of the invention are set forth in the dependent claims.

To this end, in the internal combustion engine of the above scheme, one or more further drive units are arranged in addition to the turbine in the second exhaust gas turbocharger according to the invention.

This is because an additional drive is provided before connecting the second exhaust gas turbocharger to increase the rotational speed of the second exhaust gas turbocharger, thereby providing energy from the exhaust gas flow to increase the rotational speed of the second exhaust gas turbocharger. Has the advantage that it does not need to be obtained or only a small energy needs to be obtained. In this way, the connection process is made without the rotation moment undershoot of the internal combustion engine in a simple manner.

In a preferred embodiment, the further drive device is an electric motor.

The one or more valve arrangements are for example arranged upstream and / or downstream of the second turbine of the second exhaust gas turbocharger and comprise, for example, an exhaust gas valve.

In a preferred embodiment, the at least one cylinder of the internal combustion engine comprises at least two discharge valves which are independently controllable from one another, the at least one first discharge valve of the at least one cylinder is connected in flow communication with the first turbine and the exhaust gas One or more second outlet valves of the one or more cylinders in flow connection with the second turbine, separate from the first turbine in connection with the exhaust gas flow, Periodic operation for the opening of the valve allows the second discharge valve to remain closed longer than usual in one operating cycle of the internal combustion engine and to reduce and / or shut off the exhaust gas flow by the second turbine. It is formed to be selectively blockable to form the device.

Preferably, the at least one exhaust turbocharger is formed as a single scroll exhaust turbocharger with one inlet spiral or as a twin scroll exhaust turbocharger with two inlet spirals.

In a preferred embodiment, the inlet of the first turbine of the first exhaust gas turbocharger and the inlet of the second turbine of the second exhaust gas turbocharger are connected to each other to allow flow through the crosstalk line.

Preferably the internal combustion engine comprises at least two cylinders and the exhaust gas outlets of the at least one first cylinder are connected in flow communication with the first turbine so that the exhaust gas flow from the at least one first cylinder is entirely Acting on the turbine, the exhaust gas outlets of the one or more second cylinders are connected in total flow with the second turbine, such that the exhaust gas flow from the one or more second cylinders acts entirely on the second turbine.

In a preferred embodiment, a bypass arrangement with a valve arrangement, in particular a west gate, in the first turbine and / or the second turbine is arranged to at least partially pass the exhaust gas flow in each turbine.

Preferably one or more pressure regulating valves are arranged downstream of the first compressor and / or the second compressor in the fresh air line.

In a preferred embodiment, one or more throttle valves are arranged downstream of the first compressor and / or the second compressor in the fresh air pipe.

Preferably a circulating air line with a circulating air valve is provided, which optionally connects the fresh air conduit downstream of the second compressor to flow with the fresh air conduit upstream of the second compressor.

Further, in the method of the above manner, accelerating the second exhaust gas turbocharger at a predetermined rotation speed according to the invention is carried out at least in part by an additional drive in connection with the exhaust gas turbine of the second exhaust gas turbocharger. .

This has the advantage that no energy needs to be obtained from the exhaust gas stream to accelerate the second exhaust gas turbocharger at a predetermined speed.

In a preferred embodiment, the predetermined rotational speed is determined such that the pressure conditions before and after the turbine of the second exhaust gas turbocharger correspond to the pressure conditions before and after the turbine of the first exhaust gas turbocharger.

Preferably an electric motor is used as further drive device.

In a preferred embodiment, the connection of the second exhaust gas turbocharger is made by opening the valve device in the exhaust gas pipe of the internal combustion engine.

Preferably the valve arrangement in the fresh air tube of the internal combustion engine is further opened upon connection of the second exhaust gas turbocharger.

In a preferred embodiment, the energy for driving the further drive device is obtained from an energy accumulator, in particular an electrical energy accumulator, which is supplied with energy, for example by recovery of brake energy.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

The present invention provides an improved internal combustion engine in connection with the connection of a second exhaust gas turbocharger in sequential manner.

1 is a schematic view of a first preferred embodiment of an internal combustion engine according to the invention;
2 is a schematic view of a second preferred embodiment of an internal combustion engine according to the invention;
3 is a schematic view of a third preferred embodiment of an internal combustion engine according to the invention;
4 is a schematic view of a fourth preferred embodiment of an internal combustion engine according to the invention;
5 is a schematic view of a fifth preferred embodiment of an internal combustion engine according to the invention;

The first preferred embodiment of the internal combustion engine according to the invention, shown in FIG. 1, comprises four cylinders 10, 12, 14, 16, which cylinders have a fresh air tube 18 with a suction tube 20. Fresh air stream is supplied through the exhaust gas, and the exhaust gas flow is discharged from the exhaust gas pipe 22 having the catalytic converter 24 and the lambda probe 26. The first exhaust gas turbine 28 of the first exhaust gas turbocharger 30 and the second exhaust gas turbine 32 of the second exhaust gas turbocharger 34 are disposed in the exhaust gas pipe 22, and the 2 Two exhaust gas turbines 28, 32 are arranged in the exhaust gas pipe 22 in parallel with each other in relation to the exhaust gas flow. In the fresh air pipe 18 a first compressor 36 of the first exhaust gas turbocharger 30 and a second compressor 38 of the second exhaust gas turbocharger 34 are arranged. The two compressors 36, 38 are arranged in the fresh air conduit 18 parallel to each other with respect to the fresh air flow. The first turbine 28 drives the first compressor 36, and the second turbine 32 drives the second compressor 38. The crosstalk line 40 connects each inlet of the two turbines 28, 32 to each other for flow. The first turbine 28 comprises a first bypass line 42 with a valve arrangement (west gate 1), which selectively directs at least a portion of the exhaust gas flow through the first turbine 28. do. The second turbine 32 comprises a second bypass line 44 with a valve arrangement (west gate 2), which optionally directs at least a portion of the exhaust gas flow through the second turbine 32. do. Bypass lines 42 and 44 are formed, for example, as internal west gates of respective turbines 28 and 32. The first air supply cooler 50 is disposed downstream of the first compressor 36 in the fresh air pipe 18, and the second air supply cooler 52 is disposed downstream of the second compressor 38. The second compressor 38 directs at least a portion of the air compressed by the second compressor 38 from the outlet of the second compressor 38 downstream of the second air supply cooler 52 to the inlet of the second compressor 38. Circulating air line 46 with a circulating air valve 48 to accomplish this. An exhaust gas valve 54 is disposed in the portion of the exhaust gas pipe 22 assigned only to the second turbine 32. A throttle valve 56 is disposed downstream of the two air supply coolers 50, 52 in the fresh air pipe 18. Downstream of the second air supply cooler 52, a pressure regulating valve 60 is arranged in the fresh air pipe 18.

According to the invention the second exhaust gas turbocharger 34 comprises an additional drive 58 for the second compressor 32 in the form of an electric motor in addition to the second turbine 38.

In the first preferred embodiment of the internal combustion engine according to the invention, shown in FIG. 1, the exhaust gas valve 54 is arranged away from the engine and downstream of the second turbine 32 in relation to the exhaust gas flow. Two exhaust gas turbochargers (30, 34) are formed in a SS- exhaust gas turbine (S ingle- S croll- exhaust gas turbine) with a spiral inlet in the exhaust gas turbine (28, 32). An adjustment valve (not shown) is disposed in the crosstalk line 40.

FIG. 2 shows a second preferred embodiment of the internal combustion engine according to the invention, in which functionally identical parts are denoted by the same reference numerals as in FIG. 1, so that the above description of FIG. 1 is referred to in the description. Unlike the Figure is that of the first embodiment according to the first, the first exhaust gas turbo supercharger 30, the TS- exhaust gas turbine (T S win- croll- exhaust with two spiral flows in a first exhaust gas turbine (28) Gas turbine) while a second exhaust gas turbocharger 34 is formed of an SS-exhaust gas turbine 32.

FIG. 3 shows a third preferred embodiment of the internal combustion engine according to the invention, in which functionally identical parts are denoted by the same reference numerals as in FIG. 1, so that the above description of FIG. 1 is referred to in the description. Unlike the first embodiment according to FIG. 1, an exhaust gas valve 54 is arranged near the engine and upstream of the second exhaust gas turbine 32 in relation to the exhaust gas flow. Two exhaust gas turbochargers 30, 34 are formed of SS-exhaust gas turbines 28, 32.

In all the above-described preferred embodiments according to FIGS. 1 to 3, the exhaust gas pipe 22 is supplied with the exhaust gas flow from the first cylinders 10, 16 entirely to the first turbine 28, and the second cylinder. Exhaust gas streams from 12 and 14 are formed to be supplied only to the second turbine 32.

FIG. 4 shows a fourth preferred embodiment of the internal combustion engine according to the invention, in which functionally identical parts are denoted by the same reference numerals as in FIG. 1, so that the above description of FIG. 1 is referred to in the description. Unlike the first embodiment according to FIG. 1, the exhaust gas pipe 22 is formed in two-pass, and the exhaust gas valve 54 is close to the engine and in relation to the exhaust gas flow. Upstream of the exhaust gas turbine 32 and in the crosstalk line 40. The first exhaust gas turbocharger 30 and / or the second exhaust gas turbocharger 34 comprise TS-exhaust gas turbines 28, 32.

Fig. 5 shows a fifth preferred embodiment of the internal combustion engine according to the invention, in which functionally identical parts are denoted by the same reference numerals as in Fig. 1, so that the above description of Fig. 1 is referred to in the description. Unlike the first embodiment according to FIG. 1, no crosstalk line 40 is provided. Each cylinder 10, 12, 14, 16 includes a first discharge valve 62 and a second discharge valve 64. The first discharge valve 62 is connected only to the first turbine 28 and separated from the second turbine 32 so that the flow passes in relation to the exhaust gas flow. The second discharge valves 64 are connected only to the second turbine 32 and separate from the second turbine 28 so that the flow is in connection with the exhaust gas flow. In this operating state of the internal combustion engine, where the first exhaust gas turbocharger 30 can provide only the necessary air pressure for a given engine moment, the second discharge valves 64 are closed, for example in the low end torque range. State and only the first discharge valve 62 is opened and closed periodically according to the operating cycle or the crankshaft angle. This is done for example by an exhaust camshaft with a stroke changeover switch. As a result, the exhaust gas flow is provided only to the first turbine 28. ATL 30 may be implemented in SS-ATL or TS-ATL (shown here). The first compressor 36 passes at least a portion of the air compressed by the first compressor 36 from the outlet of the first compressor 36 downstream of the first air supply cooler 50 to the inlet of the first compressor 36. A circulating air line with a circulating air valve 66 for guiding.

In the case of an internal combustion engine according to the present invention comprises a sequential system, the second, EU-ATL as an exhaust gas turbocharger (34) to be connected; is provided (U E lektrisch nterstuetzer ATL electrical support ATL). The EU-ATL 34 may be further accelerated by electrical energy in addition to the exhaust gas energy supplied to it (bypass flow of the first ATL 30 if the first ATL 30 has reached a set air supply pressure). have. Thus, on the one hand the performance of the sequential combination can be raised and on the other hand the current peaks during acceleration of the EU-ATL 34 in the sequential combination occur much less than when using the EU-ATL as a mono-ATL-concept. After the second ATL 34 first reaches the target-speed (predetermined speed) in the sequential combination, a switch to 2-ATL-operation can be made (connection of the second ATL 34), The reason is that the first ATL 30 accelerated only by the exhaust gas energy is crucial for the dynamic sense.

Ideally, the sequential system described above is used for the electric drive train, and the acceleration energy for the EU-ATL 34 is preferably obtained from an accumulator supplied with the recovered brake energy.

In conjunction with a second ATL 34 in the form of an EU-ATL, an internal combustion engine is provided having a sequential system in which the second ATL 34 can be accelerated by a mixture of exhaust gas energy and electrical energy. Thus, by providing more exhaust gas energy to the first ATL 30 in 1-ATL-operation, a higher average pressure can be obtained. At the same time, the process of switching to 2-ATL-operation (connection of the second ATL 34) can be carried out in a rotational moment neutral manner in a simple manner. In sequential charging the critical operating range of the connection step of the second ATL 34 is eliminated by the use of the EU-ATL 34. Due to this, higher performance of sequential combinations can be obtained.

10, 12, 14, 16: cylinder
18: fresh air tube
22: exhaust gas pipe
28: first turbine
30: first exhaust gas turbocharger
32: second turbine
34: second exhaust gas turbocharger
36, 38: compressor
40: crosstalk line
46: circulating air line
48: circulating air valve
54: valve device
58: drive unit
60: pressure regulating valve
62, 64: discharge valve

Claims (20)

In particular an internal combustion engine for automobiles having an electric drive train, in particular a combination of an electric motor and an internal combustion engine (hybrid engine), comprising at least one first exhaust gas turbocharger 30 and at least one second exhaust gas turbocharger 34. Wherein the first exhaust gas turbocharger includes one or more first turbines 28 and one or more first compressors 36, wherein the second exhaust gas turbocharger includes one or more second turbines 32 and one The above-described second compressor 38, wherein the first turbine 28 and the second turbine 32 are arranged in parallel with each other in relation to the exhaust gas flow in the exhaust gas pipe 22 of the internal combustion engine, The compressor 36 and the second compressor 38 are arranged parallel to each other with respect to the fresh air flow in the fresh air pipe 18 of the internal combustion engine, and at least one valve device 54; 64 in the exhaust gas pipe 22. ) To the operating status of the internal combustion engine Thus selectively reducing and / or blocking the exhaust gas flow through the second turbine 32 and at the same time without limitation permitting the exhaust gas flow through the first turbine 28 to substantially reduce the first exhaust gas turbo. In an internal combustion engine in which only the supercharger 30 is arranged and designed to generate a supply pressure,
And at least one further drive device (58) in addition to the second turbine (32) in the second exhaust gas turbocharger (34). 2. An internal combustion engine according to claim 1, wherein the further drive (58) is an electric motor. 3. An internal combustion engine according to claim 1 or 2, characterized in that said at least one valve arrangement (54) comprises an exhaust gas valve. 4. A method according to any one of the preceding claims, wherein at least one valve arrangement (54) is arranged upstream and / or downstream of the second turbine (32) of the second exhaust gas turbocharger (34). An internal combustion engine characterized by the above-mentioned. The method according to claim 1, wherein one or more cylinders 10, 12, 14, 16 of the internal combustion engine comprise two or more discharge valves 62, 64 that are independently controllable from one another. One or more first outlet valves 62 of one or more cylinders 10, 12, 14, 16 are connected in flow communication with the first turbine 28 and the second turbine 32 in connection with the exhaust gas flow. And one or more second discharge valves 64 of one or more cylinders 10, 12, 14, 16 are connected in flow communication with the second turbine 32 and in connection with the exhaust gas flow. Separated from (28), the periodic actuation for opening the second outlet valve 64 is such that the second outlet valve 64 is closed longer than normal in one operating cycle of the internal combustion engine. To reduce and / or shut off the exhaust gas flow by the second turbine 32. An internal combustion engine, characterized in that selectively formed to be blocked to form the valve device. 6. A single scroll exhaust according to any of the preceding claims, wherein at least one of the exhaust gas turbochargers (30, 34) of the exhaust gas turbocharger has one inlet spiral in the turbine (28, 32). An internal combustion engine, characterized in that it is formed as a gas turbocharger. A twin scroll exhaust according to any one of the preceding claims, wherein at least one of the exhaust gas turbochargers (30, 34) of the exhaust gas turbocharger has two inlet spirals in the turbine (28, 32). An internal combustion engine, characterized in that it is formed as a gas turbocharger. 8. The inlet of the first turbine 28 of the first exhaust gas turbocharger 30 and the second turbine of the second exhaust gas turbocharger 34. The inlet of 32 is an internal combustion engine, characterized in that connected to each other to flow through the crosstalk line (40). 9. The internal combustion engine according to any one of the preceding claims, wherein the internal combustion engine comprises at least two cylinders (10, 12, 14, 16), wherein the exhaust gas outlets of at least one first cylinder (10, 16) The flow is connected solely with the first turbine 28 so that the exhaust gas flow from one or more first cylinders 10, 16 acts solely on the first turbine 28, and the one or more second cylinders ( The exhaust gas outlets of 12 and 14 are connected in total flow with the second turbine 32 such that exhaust gas flow from one or more second cylinders 12 and 14 is entirely directed to the second turbine 32. An internal combustion engine, characterized in that it acts. 10. The bypass line (42, 44) according to any one of the preceding claims, wherein in the first turbine (28) and / or the second turbine (32) a valve arrangement, in particular with a west gate, is provided. Internal combustion engine, characterized in that it is arranged to at least partially pass the exhaust gas flow in each said turbine (28, 32). The pressure regulating valve (60) of any one of claims 1 to 10 downstream of the first compressor (36) and / or the second compressor (38) in the fresh air conduit (18). An internal combustion engine, characterized in that the arrangement. 12. The at least one throttle valve (56) of any of the preceding claims, wherein downstream of the first compressor (36) and / or the second compressor (38) in the fresh air conduit (18). An internal combustion engine, characterized in that arranged. 13. A circulating air line (46) with a circulating air valve (48) is provided, wherein said circulating air line is optionally provided with said fresh downstream of said second compressor (38). Internal combustion engine, characterized in that for connecting the air pipe (18) in flow with the fresh air pipe (18) upstream of the second compressor (38). A method of operating an internal combustion engine, wherein fresh air is compressed by a compressor in at least two turbochargers, each compressor driven by a respective exhaust gas turbine, and according to the operating point of the internal combustion engine, a first exhaust gas turbocharger A method of operating an internal combustion engine in which a second exhaust gas turbocharger is connected to the second exhaust gas turbocharger is accelerated at a predetermined rotational speed before the connection.
Accelerating the second exhaust gas turbocharger at a predetermined rotational speed is at least partly carried out by an additional drive in connection with the exhaust gas turbine of the second exhaust gas turbocharger. Way. 15. The method of claim 14, wherein the predetermined rotational speed is determined such that the pressure condition before and after the turbine of the second exhaust gas turbocharger corresponds to the pressure condition before and after the turbine of the first exhaust gas turbocharger. Operating method of internal combustion engine. 16. A method according to claim 14 or 15, wherein an electric motor is used as an additional drive. The method of operating an internal combustion engine according to any one of claims 14 to 16, wherein the connection of the second exhaust gas turbocharger is performed by opening a valve device in an exhaust gas pipe of the internal combustion engine. 18. A method according to any one of claims 14 to 17, wherein the valve arrangement in the fresh air tube of the internal combustion engine is further opened upon connection of the second exhaust gas turbocharger. 19. A method according to any one of claims 14 to 18, wherein the energy for driving said further drive device is obtained from an energy accumulator, in particular an electrical energy accumulator. 20. The method of operating an internal combustion engine according to claim 19, wherein said energy accumulator is supplied with energy, for example, by recovery of brake energy.

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