DE102013021662A1 - Charged internal combustion engine - Google Patents

Abstract

The present invention relates to a supercharged internal combustion engine (1), in particular for a utility vehicle, comprising an engine block (2) containing a plurality of cylinders (3), a fresh air system (5) for supplying fresh air to the cylinders (3), an exhaust system ( 6) for discharging exhaust gas from the cylinders (3), an exhaust gas recirculation system (7) for exhaust gas recirculation from the exhaust system (6) to the fresh air system (5), an exhaust gas turbocharger (8), the turbine (9) arranged in the exhaust system (6) is and whose compressor (10) in the fresh air system (5) is arranged, wherein a removal point (11) of the exhaust gas recirculation system (7) upstream of the turbine (9) on the exhaust system (6) is arranged, while a discharge point (12) of the exhaust gas recirculation system (7) is arranged downstream of the compressor (10) on the fresh air system (5). An improved uniform distribution of the recirculated exhaust gas to the individual cylinders is obtained if the inlet point (12) has an admixing device (25) which recirculates exhaust gas via at least two admixing openings (27) spaced from one another in a longitudinal direction (29) of the mixing section (28) a mixing section (28) of the fresh air system (5) initiates.

Description

The present invention relates to a supercharged internal combustion engine, which is particularly suitable for a commercial vehicle.

An internal combustion engine conventionally includes an engine block including a plurality of cylinders, a fresh air system for supplying fresh air to the cylinders, and an exhaust system for exhausting exhaust from the cylinders. Modern internal combustion engine are also equipped with an exhaust gas recirculation system, with the aid of which exhaust gas can be returned from the exhaust system to the fresh air system. Exhaust gas recirculation, in particular an external, ie outside the engine block, exhaust gas recirculation can be used to reduce the pollutant emissions and to improve the energy efficiency of the internal combustion engine.

A supercharged internal combustion engine is operated at an elevated pressure level. For this purpose, it is equipped for example with an exhaust gas turbocharger whose turbine is arranged in the exhaust system and the compressor is arranged in the fresh air system. In a high-pressure side exhaust gas recirculation, a removal point of the exhaust gas recirculation system upstream of the turbine is arranged on the exhaust system, while a discharge point of the exhaust gas recirculation system is arranged downstream of the compressor to the fresh air system.

Thus, the recirculated exhaust gas can flow from the exhaust system to the fresh air system, a corresponding pressure gradient is required. Such a pressure gradient may arise during normal operation of the internal combustion engine during so-called intake strokes of pistons moving in the cylinders of the engine block. As a result, the recirculated exhaust gas is sucked intermittently or in pulses and introduced into the fresh air system. While the intake strokes of the pistons within the fresh air system generate vacuum pulses which can suck exhaust gas from the exhaust gas recirculation system, the exhaust strokes of the pistons following an expansion stroke or stroke can additionally or alternatively generate pressure pulses which drive the exhaust gas into the exhaust gas recirculation system.

Inadequate mixing between the recirculated exhaust gas and the fresh air also results in the combustion chambers of the cylinder uneven distribution of the mixture of fresh air and recirculated exhaust gas, which jeopardizes the desired objectives, namely pollutant reduction and efficiency improvement.

From the DE 10 2006 035 183 A1 In general, a mixing device is known with the aid of which recirculated exhaust gas can be supplied to a fresh air system. The admixing device has a plurality of admixing openings, through which the recirculated exhaust gas is introduced into a mixing section of the fresh air system. In this case, the admixing openings are spaced apart in a longitudinal direction of the mixing section. This ensures that the intermittently sucked or expelled exhaust gases are introduced via a comparatively large longitudinal section of the fresh air system, namely via the mixing section, whereby the mixing with the fresh air improves. As a consequence, the exhaust gas recirculation rate in the individual combustion chambers can also be homogenized.

The present invention addresses the problem of providing a boosted internal combustion engine with high-pressure side exhaust gas recirculation an improved or at least another embodiment, which is characterized by an improved uniform distribution of the recirculated exhaust gases to the individual cylinders.

This problem is solved according to the invention by the subject matter of the independent claim. Advantageous embodiments are the subject of the dependent claims.

The invention is based on the general idea to equip the discharge point of the high-pressure side exhaust gas recirculation system with a Zumischeinrichtung or to realize by a Zumischeinrichtung, the admixing device via at least two Zumischöffnungen recirculated exhaust gas into a mixing section of the fresh air system initiates, wherein it is provided that the at least two Zumischöffnungen are spaced apart in a longitudinal direction of the mixing section. By this construction, the pulse-like introduction of the recirculated exhaust gas via at least two in the flow direction of the fresh air spaced admixing takes place, whereby the mixing of the recirculated exhaust gas is improved with the fresh air flow. Overall, this makes it possible to improve the uniform distribution of a mixture of recirculated exhaust gas and fresh air in the individual combustion chambers of the engine block.

According to an advantageous embodiment, the fresh air system may have a fresh air distributor, which has an inlet opening and an outlet opening for each cylinder. Since the fresh air distributor has only a single inlet opening and a plurality of outlet openings, at least one outlet opening is arranged proximal to the inlet opening, while at least one other outlet opening is arranged distally of the inlet opening. This results within the fresh air manifold different lengths of flow paths from the inlet opening to the different outlet openings. In order to counteract this, the fresh air distributor has, in the region of the inlet opening, a dividing wall which impedes a direct flow path from the inlet opening to at least one outlet opening arranged proximally to the inlet opening. As a result, the flow path from the inlet opening to this at least one proximal outlet opening is forcibly extended, as a result of which, overall, the flow paths from the inlet opening to the various outlet openings are aligned with respect to their length. This measure leads to improved mixing of the recirculated exhaust gas with the transported in the fresh air system gas, which is preferably fresh air or a fresh air-fuel mixture. An improved mixing in this way also contributes to the homogenization of the exhaust gas recirculation rate within the individual combustion chambers.

In another embodiment, the cylinders of the engine block may be divided into two groups of cylinders. For example, the cylinders may be arranged for this purpose in two different cylinder banks of the engine block, for example in a V-type engine. In an in-line engine, the two cylinder groups are then arranged expediently one behind the other. If two cylinder groups are provided, the exhaust system may be equipped with two separate exhaust manifolds or with a split exhaust manifold having two header sections. The two exhaust manifolds or the two collector sections are then expediently assigned to separate high-pressure regions of the exhaust system in order to be able to separately supply the exhaust gases of the two cylinder groups to two separate turbines or preferably to a common turbine. Preferred is an embodiment in which a twin-flow turbine is used, wherein the separate exhaust gas streams are supplied separately to the two floods of the turbine, such that each one exhaust gas flow leads to exactly one exhaust gas flow. Accordingly, the two high pressure areas of the exhaust system are connected to one of the two turbine floods. The two cylinder groups are expediently chosen such that pressure pulses in the exhaust gas within the respective cylinder group are as synchronized as possible, while the pressure pulses of one cylinder group occur asynchronously with the pressure pulses of the other cylinder group. As a result, disruptive interactions within the exhaust gas streams can be reduced.

According to an advantageous development, both turbine flows can each be controlled via a separate wastegate. A wastegate is a controlled bypass for bypassing a turbine wheel of the respective turbine. By opening the bypass or the wastegate, the pressure difference between an inlet side and an outlet side of the turbine wheel decreases, whereby the drive power of the turbine wheel is reduced accordingly. Thus, the wastegate ultimately serves to control the power of the turbine and thus of the exhaust gas turbocharger. By means of the separate waste gates assigned to the two turbine flows, the pressures in the two separate high-pressure regions can thus be separated and controlled independently of one another.

In another advantageous development, the removal point of the exhaust gas recirculation system can be connected to the exhaust system so that it is assigned to only one cylinder group. For example, the removal point is arranged on one of the two exhaust manifolds or on one of the two collector sections. Likewise, the removal point between the respective exhaust manifold and the turbine can be connected to one of the two high pressure areas of the exhaust system. By this measure, it is achieved that only in the one high-pressure region and thus only in one turbine surge, a pressure drop due to the exhaust gas recirculation takes place, so that the high pressure of the other high-pressure region or the other turbine flood can be used to generate power in the turbine. If the two turbine flows within the turbine are assigned to two different power levels anyway, the exhaust gas to be recirculated expediently takes place in a region assigned to the weaker turbine flow, so that full power can still be generated via the more powerful turbine flood.

In principle, the internal combustion engine presented here can be operated in a conventional manner with a liquid fuel which is expediently injected directly into the combustion chambers of the cylinders. Alternatively, however, an embodiment of the internal combustion engine as a gas engine is possible in which the fuel passes in gaseous form to the combustion chambers. According to an advantageous embodiment, the internal combustion engine can be equipped with a fuel mixing device, via which the gaseous fuel is introduced upstream of the engine block in the fresh air system. In this case, therefore, no introduction of the fuel takes place directly in the combustion chambers of the cylinder. The fuel mixing device is expediently connected downstream of the compressor and upstream of the discharge point of the exhaust gas recirculation system to the fresh air system. In this way, intensive mixing of the gaseous fuel with the compressed fresh air supplied via the fresh air system is initially achieved, so that the recirculated exhaust gas is subsequently introduced into a mixture of fresh air and fuel.

In another advantageous embodiment, the admixing device of the exhaust gas recirculation system can have exactly two admixing openings, which are spaced so far apart in the longitudinal direction of the mixing section that an admixing volume of the mixing section measured from one admixing opening to another admixing opening corresponds approximately to an effective cylinder volume of one of the cylinders. Suitably, all cylinders of the engine block have the same effective cylinder volume. The admixing volume thus substantially corresponds to the respective effective cylinder volume of a cylinder, wherein the term "about" or the formulation "substantially" should include deviations between the admixing volume and the effective cylinder volume of ± 10% and preferably ± 5%. The effective cylinder volume usually corresponds to about 90% of the actual geometric cylinder volume.

In an alternative embodiment, the admixing device of the exhaust gas recirculation system can have more than two admixing openings, wherein one of the transported in the fresh air system gas or gas mixture first flowed first admixing opening and one of said gas or gas mixture last flowed last admixing opening are furthest apart. In this case, the first admixing opening and the last admixing opening are spaced so far apart in the longitudinal direction of the mixing section that an admixing volume of the mixing section measured from the first admixing opening to the last admixing opening corresponds approximately to an effective cylinder volume of one of the cylinders. Also in this case, dimensional deviations between the admixing volume and the effective cylinder volume of not more than 10%, preferably of not more than 5%, are tolerated.

By dimensioning the admixing volume such that it corresponds approximately to an effective cylinder volume, it is achieved that the admixing volume is maximally sucked in at each intake stroke, so that a mixture of the recirculated exhaust gas and the gas or gas mixture transported via the fresh air line is always sucked in ,

According to a particularly advantageous development, the admixing device can have an inlet for exhaust gas to be recirculated, which is arranged upstream of the first admixing opening in the region of the first admixing opening or, with respect to the flow direction, in the fresh air system. Thus, the recirculated exhaust gas in the region of the admixing device has substantially the same flow direction as the gas or gas mixture transported in the fresh air system.

In another advantageous embodiment, the mixing section of the fresh air system can be designed as a straight pipe, which favors the achievement of a homogeneous mixing between recirculated exhaust gas and the gas or gas mixture of the fresh air system. Additionally or alternatively, the admixing device may have a pipe section which has an inlet for recirculating exhaust gas and which is connected via the admixing openings to the mixing section. In particular, in conjunction with a configured as a straight pipe mixing section results from this design a compact design for the discharge point.

Other important features and advantages of the invention will become apparent from the dependent claims, from the drawings and from the associated figure description with reference to the drawings.

It is understood that the features mentioned above and those yet to be explained below can be used not only in the particular combination given, but also in other combinations or in isolation, without departing from the scope of the present invention.

Preferred embodiments of the invention are illustrated in the drawings and will be described in more detail in the following description, wherein like reference numerals refer to the same or similar or functionally identical components.

Show, in each case schematically,

1 a greatly simplified schematic diagram of a supercharged internal combustion engine,

2 a simplified representation of the internal combustion engine in the region of a discharge point of an exhaust gas recirculation system,

3 a view like in 2 but in another embodiment,

4 an isometric view of the internal combustion engine in the region of the point of introduction, in another embodiment.

Corresponding 1 includes an internal combustion engine 1 , which is preferably arranged in a commercial vehicle, an engine block 2 , the several cylinders 3 contains, each a combustion chamber 4 enclose. The internal combustion engine 1 is also with a fresh air system 5 for supplying fresh air to the cylinders 3 as well as with an exhaust system 6 for discharging exhaust gas from the cylinders 3 fitted. Furthermore, an exhaust gas recirculation system 7 provided with the aid of exhaust gas from the exhaust system 6 to the fresh air system 5 can be returned. The internal combustion engine 1 is charged what she uses an exhaust gas turbocharger 8th equipped, its turbine 9 in the exhaust system 6 is arranged and its compressor 10 in the fresh air system 5 is arranged. The exhaust gas recirculation system 7 has a sampling point 11 for removing recirculating exhaust gas from the exhaust system 6 that are upstream of the turbine 9 at the exhaust system 6 is arranged. Furthermore, the exhaust gas recirculation system includes 7 a discharge point 12 for introducing the recirculated exhaust gas into the fresh air system 5 that is downstream of the compressor 10 at the fresh air system 5 is arranged.

Furthermore, the fresh air system shown here includes 5 an air filter 13 , upstream of the compressor 10 is arranged a bypass 14 to bypass the compressor 10 with the help of a bypass valve 15 is controllable, a charge air cooler 16 and purely by way of example a controllable throttle 17 , In addition, the fresh air system 5 with a fresh air manifold 18 equipped, which supplies the fresh air to the individual cylinders 3 distributed.

The exhaust system 6 includes at least one exhaust collector 19 that of the cylinders 3 incoming exhaust gas collects and forwards, making it to the turbine 9 arrives. Downstream of the turbine 9 contains the exhaust system 6 various emission control devices, such as a pre-catalyst 20 , a main catalyst 21 and an additional catalyst 22 , The abovementioned exhaust gas purification devices are mentioned purely by way of example, in particular in the event that the internal combustion engine 1 is designed as a gas engine which is operated with a gaseous fuel. If liquid fuels are used, the exhaust system can 6 also have other emission control devices, such as a particulate filter and an SCR system. Furthermore, the exhaust system 6 contain in the usual way at least one silencer.

The exhaust gas recirculation system 7 can optionally with an exhaust gas recirculation cooler 23 be equipped. Further, an exhaust gas recirculation valve 24 provided to adjust the exhaust gas recirculation rate.

According to the 2 to 4 can the discharge point 12 the exhaust gas recirculation system 7 a Zumischeinrichtung 25 exhibit. The admixing device 25 that leads into the 2 and 3 indicated by an arrow recirculating exhaust gas 26 via at least two admixing openings 27 in a mixing section 28 the fresh air system 5 one. The at least two admixing openings 27 are in one in the 2 to 4 indicated by a double arrow longitudinal direction 29 of the mixing section 28 spaced apart. At the in 2 shown embodiment are exactly two such Zumischöffnungen 27 intended. In the in the 3 and 4 In contrast, more than two, in particular five, admixing openings are shown 27 provided, each in the longitudinal direction 29 spaced apart from each other. According to 1 owns the fresh air distributor 18 an inlet opening 30 and per cylinder 3 an outlet opening 31 , The fresh air manifold 18 extends along the engine block 2 , The inlet opening 30 is at one longitudinal end 32 of the fresh air manifold 18 arranged laterally. In contrast, the outlet openings 31 distributed over the entire length of the fresh air manifold distributed laterally. Accordingly, the distances of the outlet openings vary 31 from the inlet opening 30 , In the fresh air manifold 18 is a partition 33 arranged in the example of the 1 at the longitudinal end 32 begins, at which also the inlet opening 30 is arranged. The partition 33 extends within the fresh air manifold 18 such that it has a direct flow path from the inlet opening 30 to at least one proximal to the inlet opening 30 arranged outlet opening 31 with special needs. In the example of 1 extends the partition 33 starting from the longitudinal end shown on the left 32 over three outlet openings 31 while they leave the remaining three outlet openings 31 left uncovered. Thus, the direct flow paths are to the three outlet ports shown on the left 31 through the partition 33 with special needs. Overall, with the help of the partition 33 thus that of the in the fresh air plant 5 transported gas or gas mixture actually traversed flow paths are matched in length with each other.

The cylinders 3 of the engine block 2 are in two cylinder groups 34 and 35 divided, what in 1 indicated by curly braces. The exhaust collector 19 is in the example as a shared exhaust collector 19 designed, the two collector sections 36 and 37 having. The first or first collector section 36 collects the exhaust gases of one or the first cylinder group 34 while the other or second collector section 37 the exhaust gases of the other or second cylinder group 34 collects and opposite the first collector section 36 is sealed. The two collector sections 36 . 37 The collected exhaust gases separate separate high pressure areas 38 . 39 the exhaust system 6 to. The turbine 9 is designed here as a double-flow turbine, so the turbine 9 Accordingly, contains two separate, here unspecified or unrecognizable turbine floods. It is noteworthy that the two turbine floods each have a separate wastegate 40 respectively. 41 are controllable. For a simplified representation are in 1 the two waste gates 40 . 41 symbolized by valves in external bypass paths 42 respectively. 43 are arranged, each of which is not shown turbine wheel of the turbine 9 bypass. Favorable are the wastegates 40 . 41 or the associated bypasses, however, within the turbine 9 educated.

The sampling point 11 the exhaust gas recirculation system 7 it's the exhaust system 6 connected that they only one of the two cylinder groups 34 . 35 assigned. In the example, the sampling point 11 the second cylinder group 35 assigned. Here is the sampling point 11 at the second collector section 37 arranged. The two unspecified turbine floods can be designed so that they have different power levels on the turbine 9 can transfer. The exhaust gas recirculation system is expedient 7 so to the exhaust system 6 connected, that it withdraws the recirculated exhaust gas ultimately the weaker turbine tide.

The preferred example shown here is the internal combustion engine 1 designed as a gas engine. The gaseous fuel is via a fuel mixing device 44 in the fresh air system 5 initiated. The fuel mixing device 44 thus connects a fuel supply system 45 with the fresh air system 5 , The fuel mixing device 44 is downstream of the compressor 10 and upstream of the discharge point 12 the exhaust gas recirculation system 7 to the fresh air system 5 connected. Accordingly, the fresh air system promotes 5 to the compressor 10 "Normal" charge air. From the compressor 10 to the fuel mixing device 44 promotes the fresh air system 5 compressed fresh air, which can also be referred to as charge air. From the fuel mixer 44 to the discharge point 12 promotes the fresh air system 5 a mixture of charge air and fuel. From the discharge point 12 up to the cylinders 3 promotes the fresh air system 5 then a mixture of recirculated exhaust gas, charge air and fuel. In the 2 and 3 the mixed fuel is indicated by an arrow and with 46 designated. Furthermore, in the 2 and 3 the charged fresh air or charge air through an arrow 47 indicated.

At the in 2 embodiment shown has the Zumischeinrichtung 25 exactly two admixing openings, namely a first admixing opening 27 ' and a second admixing opening 27 '' , The two admixing openings 27 ' . 27 '' are in the longitudinal direction 29 of the mixing section 28 so far apart that within the mixing section 28 from the one Zumischöffnung 27 ' until the other mixing opening 27 '' a Zumischvolumen 48 arises, in essence, so with a maximum deviation of 10%, preferably with a maximum deviation of 5%, an effective cylinder volume of the cylinder 3 equivalent. The mixing section 28 is here as a straight pipe 50 designed, with a longitudinal axis of this tube 50 the longitudinal direction 29 of the mixing section 28 Are defined. The admixing device 25 has a pipe section 49 on, which is also designed here straight and parallel to the pipe 50 of the mixing section 28 extends. In the example of 2 indicates the pipe section 49 at its longitudinal ends depending on a connecting pipe 51 on that the pipe section 49 with one of the admixing openings 27 fluidly connects. Exactly centered between the longitudinal ends of the pipe section 49 is an inlet opening 52 arranged over which the recirculated exhaust gas 26 in the pipe section 49 arrives.

At the in 3 the embodiment shown is the mixing section 28 again through a straight pipe 50 educated. Also the admixing device 25 owns here a straight pipe section 49 in this case, directly to the pipe 50 of the mixing section 28 connected. In particular, own the tube 50 of the mixing section 28 and the pipe section 49 the admixing device 25 a common wall 53 , wherein the admixing openings 27 through openings in this common wall 53 are formed. As mentioned are in the in 3 shown embodiment more than two admixing openings 27 intended. One of the mixture of charge air 47 and fuel 46 first infused Zumischöffnung 27 is hereinafter referred to as first Zumischöffnung 27 ' referred to while a farthest spaced, last flowed by said mixture Zumischöffnung 27 in the following as last admix opening 27 '' referred to as. Also at the in 3 embodiment shown is provided that the first admixing opening 27 ' and the last admix opening 27 '' in the longitudinal direction 29 of the mixing section 28 a Zumischvolumen indicated by a brace 48 in the mixing section 28 define the approximate effective cylinder volume of one of the cylinders 3 equivalent.

Also at the in 3 embodiment shown is the pipe section 49 the admixing device 25 the recirculated exhaust gas 26 via an inlet opening 52 fed, which also as an inlet 52 can be designated. The inlet 52 or the inlet opening 52 is according to 3 in the area of the first mixing opening 27 ' arranged. In 3 is the inlet 52 even regarding the in the fresh air plant 5 guided flow upstream of the first admixing opening 27 ' arranged.

4 shows a concrete embodiment of in 3 shown Zumischeinrichtung 25 , Visible is the exhaust gas recirculation system 7 in the area of the exhaust gas recirculation valve 24 and the discharge point 12 , From the admixing device 25 is the pipe section 49 visible to the pipe 50 of the mixing section 28 connected or grown. Upstream of the mixing section 28 is the fuel mixing device 44 indicated. Downstream goes the mixing section 28 over a curved pipe section 54 in the fresh air manifold 18 above.

QUOTES INCLUDE IN THE DESCRIPTION

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Cited patent literature

• DE 102006035183 A1 [0006]

Claims (10)

Charged internal combustion engine, in particular for a commercial vehicle, - with an engine block ( 2 ), which has several cylinders ( 3 ), - with a fresh air system ( 5 ) for supplying fresh air to the cylinders ( 3 ), - with an exhaust system ( 6 ) for removing exhaust gas from the cylinders ( 3 ), - with an exhaust gas recirculation system ( 7 ) for exhaust gas recirculation from the exhaust system ( 6 ) to the fresh air system ( 5 ), - with an exhaust gas turbocharger ( 8th ), whose turbine ( 9 ) in the exhaust system ( 6 ) is arranged and its compressor ( 10 ) in the fresh air system ( 5 ) is arranged, - wherein a sampling point ( 11 ) of the exhaust gas recirculation system ( 7 ) upstream of the turbine ( 9 ) on the exhaust system ( 6 ), - an introduction point ( 12 ) of the exhaust gas recirculation system ( 7 ) downstream of the compressor ( 10 ) at the fresh air system ( 5 ), the introduction point ( 12 ) a mixing device ( 25 ), which via at least two admixing openings ( 27 ) recirculated exhaust gas into a mixing section ( 28 ) of the fresh air system ( 5 ), - wherein the at least two admixing openings ( 27 ) in a longitudinal direction ( 29 ) of the mixing section ( 28 ) are spaced from each other. Internal combustion engine according to claim 1, characterized in that the fresh air system ( 5 ) a fresh air distributor ( 18 ) having an inlet opening ( 30 ) and per cylinder ( 3 ) at least one outlet opening ( 31 ), wherein in the region of the inlet opening ( 30 ) a partition wall ( 33 ) in the fresh air distributor ( 18 ) is arranged, which a direct flow path from the inlet opening ( 30 ) to at least one proximal to the inlet opening ( 30 ) arranged outlet opening ( 31 ) with special needs. Internal combustion engine according to claim 1 or 2, characterized in that - that the cylinders ( 3 ) in two cylinder groups ( 34 . 35 ), - that the exhaust system ( 6 ) two separate exhaust manifolds or a split exhaust collector ( 19 ) with two collector sections ( 36 . 37 ), each of a cylinder group ( 34 . 35 ) as well as separate high-pressure areas ( 38 . 39 ) of the exhaust system ( 6 ), that the turbine ( 9 ) as a twin-flow turbine ( 9 ) is configured, - that the two high pressure areas ( 38 . 39 ) are connected to one of the two turbine floods. Internal combustion engine according to claim 3, characterized in that both turbine floods in each case via a separate wastegate ( 40 . 41 ) are controlled. Internal combustion engine according to claim 3 or 4, characterized in that the removal point ( 11 ) so to the exhaust system ( 6 ) is connected to only one cylinder group ( 35 ) assigned. Internal combustion engine according to one of claims 1 to 5, characterized in that the internal combustion engine ( 1 ) is designed as a gas engine whose gaseous fuel via a fuel mixing device ( 44 ) in the fresh air system ( 5 ), wherein the fuel mixing device ( 44 ) downstream of the compressor ( 10 ) and upstream of the discharge point ( 12 ) of the exhaust gas recirculation system ( 7 ) to the fresh air system ( 5 ) connected. Internal combustion engine according to one of claims 1 to 6, characterized in that the admixing device ( 25 ) of the exhaust gas recirculation system ( 7 ) exactly two admixing openings ( 27 ' . 27 '' ), which in the longitudinal direction ( 29 ) of the mixing section ( 28 ) are so far apart that one of the one Zumischöffnung ( 27 ' ) to the other mixing opening ( 27 '' ) measured admixing volume ( 48 ) of the mixing section ( 28 ) about an effective cylinder volume of one of the cylinders ( 3 ) corresponds. Internal combustion engine according to one of claims 1 to 6, characterized in that the admixing device ( 25 ) of the exhaust gas recirculation system ( 7 ) more than two admixing openings ( 27 ), wherein a first admixing opening ( 27 ' ) and a last admixing opening ( 27 '' ) are spaced furthest from each other, wherein the first admixing opening ( 27 ' ) and the last admixing opening ( 27 '' ) in the longitudinal direction ( 29 ) of the mixing section ( 28 ) are spaced so far apart that one of the first admixing opening ( 27 ' ) to the last mixing opening ( 27 '' ) measured admixing volume ( 48 ) of the mixing section ( 28 ) about an effective cylinder volume of one of the cylinders ( 3 ) corresponds. Internal combustion engine according to claim 8, characterized in that the admixing device ( 25 ) an inlet ( 52 ) for recirculating exhaust gas, which in the region of the first admixing opening ( 27 ' ) or with respect to a gas flow in the fresh air system ( 3 ) upstream of the first admixing opening ( 27 ' ) is arranged. Internal combustion engine according to one of claims 1 to 9, characterized in that - that the mixing section ( 28 ) of the fresh air system ( 5 ) as a rectilinear tube ( 50 ), and / or - that the admixing device ( 25 ) a pipe section ( 49 ) having an inlet ( 52 ) For has exhaust gas to be recirculated and via the admixing openings ( 27 ) to the mixing section ( 28 ) connected.

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