DE102004028482B4 - Internal combustion engine - Google Patents

Abstract

 Internal combustion engine (10) having a turbocharger device with at least one first and a second turbocharger (18, 22), the compressor (19, 23) of turbochargeable turbines (20, 24) are drivable, wherein the first turbocharger (18) in a first exhaust line (16) of a first group of exhaust valves (14) of the internal combustion engine (10) and a second turbocharger (22) in a second exhaust line (17) of a second group of exhaust valves (15) is arranged, wherein at least a part of the cylinder ( 11) is connected on the outlet side to both turbochargers (18, 22), characterized in that the compressors (19, 23) of the turbocharger (18, 22) are fluidically connected in parallel and between the compressor side lines (31, 33) for supplying air to Inlet valves (12, 13) of the cylinder (11) a pressure regulating device (40) is provided.

Description

The invention relates to an internal combustion engine according to the preamble of patent claim 1.

The use of exhaust gas turbochargers for charging gasoline and diesel engines is known. At low engine speeds and exhaust gas mass flows, the charge pressure buildup takes place with a certain delay, and the resulting delayed torque build-up in the turbocharged engine can be felt as a "turbo lag". Basically, in turbo engines, a performance improvement over naturally aspirated engines is sought. With the degree of desired performance increase also increases the size of the required turbines and compressors, but this is accompanied by an increasing delay of the torque build-up at low speeds and exhaust gas mass flows. The requirement for simultaneously high performance and small turbo lag at low speeds is difficult to fulfill with a single turbocharger. Therefore, it has already been proposed to use two exhaust gas turbochargers per engine, which have improved response due to smaller turbines and compressors compared to a single turbocharger design. Such an arrangement with two turbochargers is for example in the DE 19743667 A1 described.

The DE 34 39 999 C1 discloses an internal combustion engine having two exhaust valves per cylinder, a first exhaust valve of each cylinder being connected to a turbine of a second exhaust gas turbocharger via first exhaust ports to a turbine of a first exhaust gas turbocharger and a second exhaust valve of each cylinder via second channels separated from the first channels. The compressors of the turbochargers are arranged serially.

The DE 102 43 473 A1 shows a double turbocharged supercharged by internal combustion engine, the compressors of the exhaust gas turbocharger are arranged in parallel. Upstream of a compressor, a switching valve is arranged.

The DE 198 34 762 A1 describes an internal combustion engine with a catalytic converter and a secondary air device, wherein secondary air is supplied to the exhaust gas flow in the starting phase of the internal combustion engine in order to additionally heat the exhaust gas flow.

The US 2004/0061290 A1 discloses an internal combustion engine with a catalyst in the exhaust pipe, wherein the catalyst is arranged upstream of the turbine of an exhaust gas turbocharger. Upstream of the catalyst, an oxygen-sensitive measuring device is arranged.

The EP 1 396 619 A1 shows an internal combustion engine having a first catalyst which is arranged upstream of a second catalyst in a bypass line of a turbine of an exhaust gas turbocharger in the exhaust pipe.

Object of the present invention is to improve the torque build-up of a turbo engine at low speeds on.

The object is achieved with the features of claim 1.

In the internal combustion engine according to the invention with a turbocharger device having at least a first and a second turbocharger, the compressor is driven by turbochargeable turbines, the first turbocharger in a first exhaust line of a first group of exhaust valves of the internal combustion engine and the second turbocharger in a second exhaust line of a second group of exhaust valves arranged. The first turbocharger is acted upon by the outlet valves of the first group and the second turbocharger by the exhaust valves of the second group, wherein at least a part, preferably all, of the cylinder of the internal combustion engine is connected on the outlet side to both turbochargers. This means that always only a part of the exhaust valves of at least part of the cylinders acts on one of at least two turbochargers.

Further according to the invention, the compressors of the turbocharger are connected in parallel, in particular, these promote in the same pressure line. At a merger of compressor-side lines of a suction device, a pressure control device is provided, which ensures that a possible different boost pressure of both compressors in special operating conditions, such as when switching the exhaust valves caused interference. The pressure control device may be passive, for example, via a pivotable element which, depending on the pressure conditions in the flow direction sets before the merge a same boost pressure, or active via one or two operable via actuators throttle devices, depending on a respective pressure sensor between the compressor and the merge be controlled. Another pressure sensor may be provided downstream of the merge. It is advantageous if the pressure in the compressor-side lines can be regulated to the same desired value.

It is useful to provide additional valve lift and / or timing of the individual exhaust valves of a cylinder independently adjustable. At least two exhaust valves per cylinder are provided. Preference is given to pro Cylinder head at least two turbochargers, especially exactly two turbochargers, provided. Preferably, the internal combustion engine is externally ignited, particularly preferably designed direct injection.

Advantageous developments of the invention are specified in subclaims.

Preferably, the first turbocharger is designed to be smaller than the second turbocharger. It makes sense that the second turbocharger is designed for the rated output of the internal combustion engine. In particular, the first turbocharger is designed to be significantly smaller than the second turbocharger and dimensioned so small that a spontaneous response and a rapid torque build-up in the lower speed range is ensured. The turbine of the second turbocharger is preferably designed to be larger than in a comparable single-stage charging. Advantageously, the tuning between the at least two turbochargers is designed so that there is a harmonious transition between the operation with the first and the second turbocharger. It is favorable to then execute the first turbocharger with a twin-flow turbine as a so-called "twin-scroll" loader, in which a particularly low exhaust counterpressure is achievable if the control times are the same for both groups of exhaust valves, in particular if no short valve timing for the exhaust valves the first group are provided, or if a late outlet closing is desired to achieve low levels of pollutants in the exhaust gas mass flow.

Preferably, at least a portion of the second turbocharger acting exhaust valves is designed to be switched off, particularly preferably all the second turbocharger acting exhaust valves are at least reduced in flow, ideally switched off. The advantage is that at low speeds and exhaust gas mass flows, the entire exhaust flows through only the first turbocharger or its turbine. The shutdown can be carried out in a conventional form of valve deactivation, for example as a bent connecting rod, or as a fully variable valve train or the like.

In a favorable embodiment, the exhaust valves acting on the first turbocharger may be configured differently in diameter from the exhaust valves acting on the second turbocharger. Preferably, these exhaust valves acting on the first turbocharger have a smaller diameter. In particular, if the exhaust valves acting on the first turbocharger are made smaller in diameter, a distribution of the exhaust gas mass flow in favor of the second exhaust gas turbocharger can be established when the two turbochargers are acted on. Preferably, the first turbocharger without a bypass circuit, i. without so called "waste gate".

In a further favorable embodiment, a valve lift curve and / or a duration of the valve opening and / or control times of the exhaust valves of the first group may be different from those of the exhaust valves of the second group. Preferably, the first group belonging, the first turbocharger acting exhaust valves have shorter timing than the belonging to the second group, the second turbocharger acting exhaust valves.

In a favorable further development, switched off exhaust valves provided for acting upon the second turbocharger can be activated stepwise as the exhaust gas mass flow increases. If, in the event of an increase in the mass flow, for example during an acceleration process from a low rotational speed, the connection of the second turbocharger is required, the dynamic torque curve of the second turbocharger can be improved. An advantageous mode of operation results when the turn-off outlet valves are activated step by step, e.g. in a 6-cylinder engine by connecting in six, three or two steps to one, two or three exhaust valves. The activation is expediently carried out in N / m steps in the case of an N-cylinder engine, where m is an integer with 1 ≦ m ≦ N. It makes sense that the ratio N / m is an integer. The connection can preferably be made time-dependent and / or load-dependent and / or speed-controlled or speed-controlled depending on a Saugrohrdruck downstream of the compressor.

In a favorable development, the design of an exhaust gas purification system is adapted to the configuration of the preferred turbocharger device. Preferably, in the first exhaust gas line, a first exhaust gas catalyst is provided, preferably a small volume, close to the engine pre-catalyst, which may be arranged in front of or behind the first turbocharger seen in the exhaust gas flow direction.

It is favorable, in the exhaust gas flow direction behind the second turbocharger, to provide a second catalytic converter after merging the first and second exhaust gas lines. Preferably, the second catalyst is a main catalyst. During a heating phase of the exhaust aftertreatment initially only the first turbocharger is acted upon until the second catalyst has reached its predetermined minimum operating temperature. Advantageously, it follows that the low exhaust back pressures lead to improvements in the combustion process with a resulting improvement in the torque increase and fuel consumption advantages. The second turbocharger can be acted upon in the alternative in this phase to the first turbocharger relieve, if the resulting exhaust gas mass flow would lead to an impermissible operating state of the first turbocharger. Conveniently, the second catalyst is larger in volume than the first catalyst, preferably 1.5 times as large, twice as large or four times as large.

Due to the preferred flow of the first turbocharger in the warm-up phase, an exhaust gas sensor can be simplified. Preferably, an oxygen-sensitive measuring device is provided upstream of the first catalyst and downstream of the second catalyst. The first oxygen-sensitive measuring device upstream of the first catalytic converter may be arranged in front of or behind the first turbocharger. It is advantageously used a broadband lambda probe. The second oxygen-sensitive measuring device downstream of the second catalyst can preferably be designed for trim regulation as a lambda probe with a step response. For individual monitoring of the catalysts and / or increased exhaust gas monitoring, a third oxygen-sensitive measuring device may be provided downstream of the first catalyst and upstream of the second catalyst. A favorable installation position of the third oxygen-sensitive measuring device is after the merging of the two exhaust gas lines. Downstream of the second turbocharger and upstream of the merge, no oxygen sensitive sensing device is required.

If a secondary air supply line in the exhaust gas is necessary, this can preferably be provided only in the first exhaust gas line. A favorable installation position is downstream of the first turbocharger acting exhaust valves and upstream of the first close-coupled catalyst. This configuration shows further advantages, in particular in the case of a longitudinal installation, since no short paths to the first and second turbochargers are required for rapid torque build-up. It is expedient to keep an exhaust gas feed to the first turbocharger as short as possible, while the second turbocharger may be further spaced apart. In the direction of travel, the second turbocharger can thus be located further back than the first turbocharger, which brings significant space advantages in longitudinal installation.

In a favorable alternative embodiment, the turbocharger compressors may be connected in series, with the pressure ratios of the turbochargers multiplying. This achieves a high boost pressure. Preferably, the first turbocharger is switched off at rated power to avoid overloading the first turbocharger. Expediently, the exhaust valves of both groups of exhaust valves can be switched off in order to protect the turbine from exhaust gas in order to protect the deactivated first turbocharger.

The turbocharger device according to the invention can be provided both in engines with even and odd cylinder number, as well as more than just a cylinder head can be provided. Preferably, exactly two turbochargers per cylinder head are provided. Thus, an arrangement with two turbochargers can also be realized on an engine with an odd number of cylinders, for example a 5-cylinder engine.

Further embodiments and aspects of the invention are explained in greater detail below with reference to a drawing, independently of a summary in the patent claims without limiting the generality. Show

1 a preferred turbocharger apparatus according to a first embodiment with a 6-cylinder engine with two turbochargers with valve shutdown and an arrangement of oxygen-sensitive measuring devices and a secondary air injection;

2 a preferred turbocharger apparatus according to the first embodiment with longitudinal installation of the turbocharger;

3 a preferred turbocharger apparatus according to the first embodiment with suction device;

4 a preferred pressure control device for the suction in 3 ;

5 a preferred turbocharger device with a 4-cylinder engine;

6 a preferred turbocharger device with a 5-cylinder engine.

1 shows to illustrate the invention, a turbocharger apparatus according to a first embodiment with an engine designed as a 6-cylinder engine 10 whose cylinder 11 two intake valves each 12 and 13 and at least two exhaust valves 14 and 15 exhibit. The internal combustion engine 10 has a cylinder head. In an internal combustion engine 10 with multiple cylinder heads are preferably per cylinder head of the engine 10 two turbochargers 18 and 22 provided, more preferably exactly two turbochargers per cylinder head are provided.

Details of a suction device containing the compressors 19 and 23 supplied, are not shown in this figure. For several similar elements only one is provided with reference numerals. Furthermore, the same reference numerals are used in the various figures of the drawing for the same elements.

The exhaust valves 14 and 15 form two groups of exhaust valves 14 . 15 , The first group of exhaust valves 14 is with a manifold of a first exhaust line 16 and the second group of exhaust valves 15 is with a manifold of a second exhaust line 17 connected. In the first exhaust system 16 is a first turbocharger 18 with a compressor 19 and a turbine 20 arranged. The turbine 20 is from an exhaust gas mass flow of the first group associated exhaust valves 14 pressurizes and drives the compressor 19 at. In the second exhaust system 17 is a second turbocharger 22 with a compressor 23 and a turbine 24 arranged. The turbine 24 is from an exhaust gas mass flow of the second group associated exhaust valves 15 pressurizes and drives the compressor 23 at.

At least part of the second turbocharger 22 acting exhaust valves 15 is designed switchable, preferably all exhaust valves 15 switched off. At low speeds of the internal combustion engine 10 is essentially just the turbine 20 the first turbocharger 18 Exhaust gas flows through from the exhaust valves 14 is charged. The for charging the second turbocharger 22 provided shutdown exhaust valves 15 are gradually activated with increasing exhaust gas mass flow. This can be done for example via an unillustrated engine control unit. Will any shut off exhaust valve 15 activated individually, this is done in six steps. Be the exhaust valves 15 activated in pairs, are three steps, each will have three exhaust valves 15 are two steps to fully activate all the exhaust valves 15 necessary. A valve lift curve and / or timing of the exhaust valves 14 The first group may differ from those of the exhaust valves 15 be different from the second group.

Each of the cylinders 11 is about his exhaust valves 14 . 15 with both turbochargers 18 and 22 connected. The first turbocharger 18 is preferably designed smaller than the second turbocharger 22 , where the second turbocharger 22 on the rated power of the internal combustion engine 10 is designed. The turbine 24 of the second turbocharger 22 is designed larger than a comparable one-stage charging. The first turbocharger 18 acting exhaust valves 14 are different in diameter, preferably smaller, than the second turbocharger 22 acting exhaust valves 15 ,

Optionally, a secondary air supply line 28 with in each connecting line of the first group of exhaust valves 14 to the manifold of the first exhaust line 16 protruding feeders 29 be provided. In the first exhaust system 16 is a first catalytic converter 25 intended. In the exhaust gas flow direction behind the second turbocharger 22 is a second catalyst 26 after a merge 27 the manifolds of the first and second exhaust line 16 and 17 intended. Upstream of the first catalyst 25 and downstream of the second catalyst 26 in each case an oxygen-sensitive measuring device 41 and 42 intended. The oxygen-sensitive measuring device 41 preferably includes a broadband lambda probe while the oxygen sensing measuring device 42 preferably comprises a lambda probe with step response. It can also be a third oxygen-sensitive measuring device 43 downstream of the first catalyst 25 before or after the merge 27 be provided, in particular before the merger 27 ,

The preferred embodiment in 2 shows an arrangement according to the embodiment of 1 , which is particularly suitable for longitudinal installation, seen from their required small space. Details such as a possibly existing secondary air supply line, a suction device or an exhaust gas sensor system are not shown.

Seen in the direction of travel is the second turbocharger 22 behind the first turbocharger 18 , The exhaust system 16 to the first turbocharger 18 can be made significantly shorter than the second turbocharger 22 whose length of the exhaust line 17 is not critical. The first turbocharger 18 , the first catalyst 25 , the second turbocharger 22 and he second catalyst 26 are arranged sequentially in this order.

3 illustrates a suction device of an arrangement according to the first embodiment. Details such as a possibly existing secondary air supply line or an exhaust gas sensor system are not shown. The compressor 19 the first turbocharger 18 is via a suction line 30 supplied with supply air via a pressure line 31 and a distribution line 38 to the intake valves 12 . 13 is directed. The compressor 23 of the second turbocharger 22 is via a suction line 32 supplied with supply air via a pressure line 33 and a distribution line 38 to the intake valves 12 . 13 is directed. The two pressure lines 31 and 33 lead to a merger 34 into the distribution line 38 that have feeders 36 . 37 the compressed air to the intake valves 12 . 13 the cylinder 11 distributed.

In principle, the compressors 19 and 23 the turbocharger 18 and 22 be connected in series, with the first turbocharger 18 designed to be switched off at rated power. It is expedient, the exhaust valves 14 . 15 the first and the second group can be switched off.

Alternatively, the compressors 19 and 23 the turbocharger 18 and 22 be connected in parallel, taking part in the merge 34 of the Compressor-side pressure lines 31 and 33 a pressure control device 40 is provided to possible boost pressure differences of the two compressors 19 . 23 compensate. This circuit of the compressor 19 and 23 is preferred. 4 illustrates in a schematic representation of the pressure control device 40 , At the merger 34 is a flap 35 provided, which is continuously movable and active or passive controllable. By partially obstructing the two pressure lines 31 and 33 Both are pressure lines 31 . 33 adjusted to the higher of the two boost pressures, including in each of the pressure lines 31 . 33 in each case a pressure sensor P1 or P2 is provided. In the distribution line 38 Optionally, a third pressure sensor P3 may be provided.

The arrangement in 5 illustrates a preferred turbocharger device according to a second embodiment of an engine designed as a 4-cylinder engine 10 Details of a secondary air supply line or a suction device or an exhaust gas sensor are not shown. Preferably, the internal combustion engine 10 an inline engine or a VR engine. The internal combustion engine 10 has a cylinder head. cylinder 11 the internal combustion engine 10 each have two inlet valves 12 and 13 and at least two exhaust valves 14 and 15 on. In an internal combustion engine 10 with multiple cylinder heads are preferably per cylinder head of the engine 10 two turbochargers 18 and 22 provided, particularly preferred are exactly two turbochargers 18 . 22 provided per cylinder head.

The exhaust valves 14 and 15 form two groups of exhaust valves 14 . 15 , The first group of exhaust valves 14 is with a manifold of a first exhaust line 16 and the second group of exhaust valves 15 is with a manifold of a second exhaust line 17 connected. In the first exhaust system 16 is a first turbocharger 18 with a compressor 19 and a turbine 20 arranged. The turbine 20 is from an exhaust gas mass flow of the first group associated exhaust valves 14 pressurizes and drives the compressor 19 at. In the second exhaust system 17 is a second turbocharger 22 with a compressor 23 and a turbine 24 arranged. The turbine 24 is from an exhaust gas mass flow of the second group associated exhaust valves 15 pressurizes and drives the compressor 23 at.

At least part of the second turbocharger 22 acting exhaust valves 15 , preferably all, is designed to be switched off. At low speeds of the internal combustion engine 10 is essentially just the turbine 20 the first turbocharger 18 flows through exhaust gas. The for charging the second turbocharger 22 provided shutdown exhaust valves 15 are gradually activated with increasing exhaust gas mass flow. This can be done for example via an unillustrated engine control unit. Will any shut off exhaust valve 15 activated individually, this is done in four steps. Be the exhaust valves 15 activated in pairs, two steps are necessary.

The features and variants mentioned for the first embodiment apply here accordingly. Furthermore, the statements apply mutatis mutandis to internal combustion engines 10 with an 8-cylinder engine with two cylinder heads and 4 turbochargers 18 . 22 and 16-cylinder engines with two or four cylinder heads and four or eight turbochargers 18 . 22 ,

How out 6 can be seen, according to a third embodiment, a preferred exhaust valve related turbocharger device with two turbochargers 18 . 22 also for an internal combustion engine 10 be used with odd number of cylinders and a single cylinder head.

In the exemplary embodiment, the internal combustion engine is designed as a 5-cylinder engine. cylinder 11 the internal combustion engine 10 each have two inlet valves 12 and 13 and at least two exhaust valves 14 and 15 on. Details of a secondary air supply line and / or an intake device and / or an exhaust gas sensor system are not shown. In an internal combustion engine 10 with multiple cylinder heads are preferably per cylinder head of the engine 10 two turbochargers 18 and 22 provided, more preferably exactly two turbochargers per cylinder head are provided.

The exhaust valves 14 and 15 form two groups of exhaust valves 14 . 15 , The first group of exhaust valves 14 is with a manifold of a first exhaust line 16 and the second group of exhaust valves 15 is with a manifold of a second exhaust line 17 connected. In the first exhaust system 16 is a first turbocharger 18 with a compressor 19 and a turbine 20 arranged. The turbine 20 is from an exhaust gas mass flow of the first group associated exhaust valves 14 pressurizes and drives the compressor 19 at. In the second exhaust system 17 is a second turbocharger 22 with a compressor 23 and a turbine 24 arranged. The turbine 24 is from an exhaust gas mass flow of the second group associated exhaust valves 15 pressurizes and drives the compressor 23 at.

The features and variants mentioned for the first and second embodiments apply here accordingly.

Claims (24)

Internal combustion engine ( 10 ) with a turbocharger device having at least a first and a second turbocharger ( 18 . 22 ), whose compressor ( 19 . 23 ) of exhaust gas turbines ( 20 . 24 ) are drivable, wherein the first turbocharger ( 18 ) in a first exhaust gas line ( 16 ) of a first group of exhaust valves ( 14 ) of the internal combustion engine ( 10 ) and a second turbocharger ( 22 ) in a second exhaust line ( 17 ) of a second group of exhaust valves ( 15 ) is arranged, wherein at least a part of the cylinder ( 11 ) on the exhaust side with both turbochargers ( 18 . 22 ), characterized in that the compressors ( 19 . 23 ) the turbocharger ( 18 . 22 ) are connected in parallel in terms of flow and between compressor-side lines ( 31 . 33 ) for supplying air to intake valves ( 12 . 13 ) the cylinder ( 11 ) a pressure control device ( 40 ) is provided.  Internal combustion engine according to claim 1, characterized by a spark ignition design. Internal combustion engine according to claim 1 or 2, characterized in that the first turbocharger ( 18 ) is smaller than the second turbocharger ( 22 ). Internal combustion engine according to claim 3, characterized in that the second turbocharger ( 22 ) to the rated power of the internal combustion engine ( 10 ) is designed. Internal combustion engine according to one of the preceding claims, characterized in that at least a part of the second turbocharger ( 22 ) acting exhaust valves ( 15 ) is formed reducible in flow. Internal combustion engine according to claim 5, characterized in that the part of the second turbocharger acting exhaust valves ( 15 ) is designed to be switched off. Internal combustion engine according to one of the preceding claims, characterized in that the first turbocharger ( 18 ) acting exhaust valves ( 14 ) in diameter different from the second turbocharger ( 22 ) acting exhaust valves ( 15 ) are formed. Internal combustion engine according to claim 7, characterized in that the first turbocharger ( 18 ) acting exhaust valves ( 14 ) smaller in diameter than the second turbocharger ( 22 ) acting exhaust valves ( 15 ) are formed. Internal combustion engine according to one of the preceding claims, characterized in that a valve lift and / or control times of the exhaust valves ( 14 ) of the first group of a valve lift and / or timing of the exhaust valves ( 15 ) of the second group are different. Internal combustion engine according to one of the preceding claims, characterized in that for acting on the second turbocharger ( 22 ) provided shutdown exhaust valves ( 15 ) are gradually activated with increasing exhaust gas mass flow. Internal combustion engine according to claim 10, characterized in that the activation takes place in an N-cylinder engine in N / m steps, where m is an integer with 1 ≤ m ≤ N. Internal combustion engine according to one of the preceding claims, characterized in that per cylinder head two turbochargers ( 18 . 22 ) are provided. Internal combustion engine according to claim 12, characterized in that one of the turbochargers ( 18 . 22 ) is designed without bypass valve. Internal combustion engine according to claim 13, characterized in that the first turbocharger ( 18 ) is designed without bypass valve. Internal combustion engine according to one of the preceding claims, characterized in that in the first exhaust gas line ( 16 ) a first catalytic converter ( 25 ) is provided. Internal combustion engine according to claim 15, characterized in that the first catalytic converter ( 25 ) upstream of the turbocharger ( 18 ) is provided. Internal combustion engine according to claim 15, characterized in that the first catalytic converter ( 25 ) downstream of the turbocharger ( 18 ) is provided. Internal combustion engine according to one of claims 15 to 17, characterized in that in the exhaust gas flow direction behind the second turbocharger ( 22 ) a second catalyst ( 26 ) after a merge ( 27 ) of the first and the second exhaust line ( 16 . 17 ) is provided. Internal combustion engine according to claim 18, characterized in that the second catalyst ( 26 ) in volume greater than the first catalyst ( 25 ) is trained. Internal combustion engine according to one of the preceding claims, characterized in that upstream of the first catalyst ( 25 ) and downstream of the second catalyst ( 26 ) each an oxygen-sensitive measuring device ( 41 . 42 ) is provided. Internal combustion engine according to claim 20, characterized in that a third oxygen-sensitive measuring device ( 43 ) upstream of the second catalyst ( 26 ) is provided. Internal combustion engine according to claim 21, characterized in that the third oxygen-sensitive measuring device ( 43 ) downstream of the merge ( 27 ) is provided. Internal combustion engine according to one of the preceding claims, characterized in that a secondary air supply line ( 28 ) only in the first exhaust gas line ( 16 ) is provided. Internal combustion engine according to one of the preceding claims, characterized in that the pressure in the compressor-side lines ( 31 . 33 ) can be adjusted to the same desired value.

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