DE102013201710A1 - Internal combustion engine, such as gas engine, lean gas engine or diesel engine, is provided with upstream of two valve units that is arranged on exhaust gas treatment elements and combustion air line to supply combustion air to cylinders - Google Patents

Abstract

The internal combustion engine (1) comprises a combustion air line (5) to supply the combustion air to two cylinders (3). An exhaust manifold (7) discharges an exhaust gas from the cylinders. A cylinder is directly connected with the exhaust manifold in a fluid manner without branching to an exhaust gas recirculation line (11). A valve unit (21) for the exhaust manifold is arranged in a fluid path (19) of another cylinder. Another valve unit (23) is arranged in the exhaust gas recirculation line. The upstream of two valve units is arranged on the exhaust gas treatment elements (25,27).

Description

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

Internal combustion engines of the type discussed here are known. From the German patent application DE 199 60 998 C1 shows an internal combustion engine having a total of six cylinders, of which five cylinders form a group of first cylinders, and wherein the remaining cylinder is formed as a second cylinder. There is provided a combustion air conduit for supplying combustion air to the cylinders and an exhaust manifold for discharging exhaust gas from the cylinders. Furthermore, the internal combustion engine has an exhaust gas recirculation line. The cylinders of the group of first cylinders are fluidly connected directly to the exhaust manifold without a branch to the exhaust gas recirculation line. In a fluid path of the second cylinder to the exhaust manifold, a first valve means is arranged, through which a stream of exhaust gas emitted from the second cylinder can be divided to a first, flowing into the exhaust manifold partial flow and a second, flowing in the exhaust gas recirculation line to the combustion air duct partial flow. In the exhaust gas recirculation line, a second valve device is arranged, through which a flow cross section of the exhaust gas recirculation line is variable.

Overall, in this way, a so-called donor cylinder concept is realized in which only the exhaust gas of selected cylinders is used for exhaust gas recirculation, these cylinders being referred to as donor cylinders, while the exhaust gas of other cylinders is not used for exhaust gas recirculation. The dispenser cylinder concept is particularly applied to internal combustion engines having a positive purge gradient, which means that a pressure in the combustion air conduit is generally greater than a pressure in the exhaust manifold. In this case, it is necessary to accumulate the exhaust gas for efficient recirculation in order to achieve a negative purge gradient, in which the pressure in the combustion air line is lower than the exhaust gas pressure. However, this is problematic because due to the increased exhaust back pressure larger charge exchange losses occur in the cylinders, whereby the efficiency of the internal combustion engine decreases. It is therefore advantageous if the exhaust gas pressure is not increased for all, but only for selected cylinders. Therefore, only for the donor cylinders an exhaust gas flow is dammed by means of the first valve device to bring about a negative purge gradient in the donor cylinder, while the remaining cylinders, which are not used for exhaust gas recirculation, may have a positive purge gradient, so that the pressure in the exhaust manifold here in general may be lower than the pressure in the combustion air duct. As a result, charge exchange losses are minimized. The second valve device is generally used to set an exhaust gas recirculation rate, ie the control and / or regulation of the recirculated exhaust gas quantity. Overall, the recirculated exhaust gas flow is determined by the position of both the first and the second valve device.

It is obvious that the damming of the exhaust gas in the region of the dispenser cylinder by means of the first valve device leads to an increased exhaust back pressure and thus to charge exchange losses. At the same time, it is shown that continuously stricter emissions regulations make exhaust gas aftertreatment necessary, wherein an exhaust gas aftertreatment element, for example an oxidation catalytic converter, is typically arranged in the exhaust gas manifold downstream of the first valve device. The exhaust aftertreatment element increases the exhaust back pressure in the exhaust pipe for all cylinders, so that additional charge exchange losses occur for the donor cylinder, wherein now also occur for the non-donor cylinder charge exchange losses due to the exhaust aftertreatment element. The known arrangement described here is therefore disadvantageous because on the one hand the increased exhaust gas pressure is built up in the donor cylinder by a passive element which has no further function than just this pressure increase, while at the same time for all cylinders an additional exhaust gas back pressure is established by the exhaust aftertreatment element.

It turns out another: An exhaust gas recirculation, which is provided in diesel engines mainly for influencing the emissions, is also provided in particular for gas engines to extend a knock limit or power limit. Gas engines, in particular lean-burn engines, are in fact limited in their power or in their compression ratio by knocking. Due to the recirculation of exhaust gas, an increased proportion of inert gas in the cylinders is achieved, which has a positive effect on the knock limit. It turns out, however, that unburned hydrocarbons, carbon monoxide and nitrogen monoxide are recirculated to the combustion chambers of the cylinders with the exhaust gas, especially in the case of gas engines due to the exhaust gas recirculation. These species have high reactivity, which in turn adversely affects the knock limit and cyclical variations in engine performance. As a result, at least a part of the inherently positive influence of the exhaust gas recirculation is negatively compensated.

The invention has for its object to provide an internal combustion engine that does not have at least one of the disadvantages mentioned.

This object is achieved by providing an internal combustion engine having the features of claim 1. This is characterized in that upstream of the first and / or the second valve device, an exhaust gas aftertreatment element is arranged.

If an exhaust gas aftertreatment element is arranged upstream of the first valve device, this increases the exhaust back pressure for the at least one second cylinder, and thus the donor cylinder, in addition to the first valve device. In order to achieve a predetermined pressure level, therefore, the first valve device can be designed differently and / or controlled differently, in particular its passage cross-section can be increased in comparison to an internal combustion engine without appropriately arranged exhaust aftertreatment element. The leading to charge cycle losses exhaust back pressure is at least not built up so exclusively by a passive element without further function, but at least by the exhaust aftertreatment element, which also has a positive effect on the emissions of the internal combustion engine. Accordingly, it is possible to form a downstream in the exhaust manifold downstream of the first valve means arranged exhaust aftertreatment element smaller or even completely omitted, so that here a reduced back pressure arises. Thus, the at least one first cylinder, thus the at least one non-donor cylinder, is loaded with a lower exhaust counterpressure, as a result of which the charge exchange losses decrease, so that the overall efficiency of the internal combustion engine increases. The functions of ensuring, on the one hand, a negative purge gradient in the region of the at least one dispensing cylinder and, on the other hand, providing exhaust gas aftertreatment are thus combined in a positive manner, so that, in particular in the event that no further exhaust gas after-treatment element is provided downstream of the first valve device in the exhaust gas manifold After treatment of a partial exhaust gas flow without consumption deterioration results by higher exhaust back pressure. In other words, the exhaust gas backpressure to be established anyway in the area of the at least one dispensing cylinder is usefully used for exhaust aftertreatment.

An arrangement of the exhaust aftertreatment element upstream of the first valve device is particularly preferred in connection with an internal combustion engine which is designed as a diesel engine. In this case, in particular the advantages in connection with the charge exchange losses have a favorable effect. By contrast, in the case of an internal combustion engine designed as a diesel engine, it is less relevant whether the recirculated exhaust gas comprises a high proportion of inert gas, since the knock limit is less critical than in a gas engine. If the internal combustion engine is therefore designed as a diesel engine, an exhaust gas aftertreatment element is preferably arranged only upstream of the first valve device. This does not exclude that in another embodiment, an exhaust aftertreatment element may be arranged in front of the second valve means. It is also not excluded that in one embodiment of the internal combustion engine, which is designed as a diesel engine, only an upstream exhaust gas aftertreatment element is arranged upstream of the second valve device.

If an exhaust gas aftertreatment element is arranged upstream of the second valve device, this is passed through the exhaust gas supplied to the combustion air line, which is thus purified. This has a positive effect on the knock limit, especially in the case of a gas engine, especially in the case of a lean-burn gas engine. This is especially true for an embodiment in which the exhaust aftertreatment element is designed as an oxidation catalyst, wherein in this unburned hydrocarbons are oxidized to CO ₂ and H ₂ O, CO to CO ₂ and NO to NO ₂ . As a result, the proportion of inert gas in the exhaust gas is increased or reactive constituents of the exhaust gas are reduced, in particular oxidized. This results in an extension of the knock limit, whereby the efficiency of the internal combustion engine can be increased. In particular, it is possible to increase the compression ratio and / or to postpone the ignition timing without fear of negative knocking effects. Due to the increased proportion of inert gas, it is possible to reduce the exhaust gas recirculation rate, which in turn results in lower charge exchange losses, and as a result of which the cooling requirement, and thus the power consumption of an exhaust gas recirculation cooler, can be reduced.

An embodiment is therefore preferred in which the internal combustion engine is designed as a gas engine, in particular as a lean-burn gas engine, wherein an exhaust-gas aftertreatment element is arranged only upstream of the second valve device. This does not exclude that in another embodiment, only an upstream exhaust gas aftertreatment element may be arranged upstream of the first valve device. Furthermore, this does not exclude that in a further embodiment of the internal combustion engine, which is designed as a gas engine, both upstream of the first valve means and upstream of the second valve means may be provided an exhaust aftertreatment element. Such embodiments are also encompassed by the invention.

The fact that the exhaust gas flow emitted by the at least one second cylinder can be divided preferably includes that the entire emitted exhaust gas flow can be guided into the exhaust gas manifold by means of the first valve device or fed to the combustion air line via the exhaust gas recirculation line. An exemplary embodiment is preferred in which the first valve device is additionally designed so that the exhaust gas flow can be divided variably and particularly preferably steplessly onto the two partial flows. In particular, it is possible in this way to build up a variable exhaust gas pressure for the exhaust gas recirculation as needed.

With the aid of the second valve device, the flow cross section of the exhaust gas recirculation line is preferably continuous, that is to say infinitely variable.

It is possible that the internal combustion engine has only two cylinders, of which a first cylinder is not used for exhaust gas recirculation, while a second cylinder serves as a donor cylinder. In another embodiment, it is possible that the internal combustion engine has more than two cylinders, wherein at least one cylinder is designed as a first cylinder, ie as a non-donor cylinder, and at least one cylinder as a second cylinder, thus as a donor cylinder. In particular, an embodiment is possible in which a group of first cylinder is provided, wherein a cylinder is designed as a dispensing cylinder. An embodiment is also possible in which a group of first cylinders is provided, whereby a group of at least two dispenser cylinders is also provided.

Finally, it is also possible that in one exemplary embodiment a number of second cylinders, thus dispenser cylinders, is variable, this being preferably achieved by providing more than one first valve device, wherein different first valve devices are assigned to different cylinders. In this case, by means of the first valve devices in each case a fluid connection from an associated cylinder to an exhaust gas recirculation line in a first functional position releasable and lockable in a second functional position, so that the cylinders can be preferably activated or deactivated individually with respect to their function as a donor cylinder. Preferably, a passage cross-section of the first valve means is variable, wherein particularly preferably emitted from a corresponding cylinder exhaust stream is continuously divisible to a first, flowing in the exhaust manifold partial flow and a second, flowing in the exhaust gas recirculation line to the combustion air duct partial flow.

The exhaust gas pressure in the exhaust gas recirculation line is predetermined essentially by the position of the first valve device, while a position of the second valve device essentially determines the exhaust gas recirculation rate. Preferably, the first and / or the second valve device is / are formed as a flap (s). Therefore, the first valve device is also referred to as dispenser cylinder flap, while the second valve device is also referred to as the exhaust gas recirculation flap. Ultimately, the actual recirculated exhaust gas flow is determined by the position of both the first and the second valve device.

An internal combustion engine is preferred, which is characterized in that the combustion air line has a compressor arrangement with at least one compressor. In this case, the exhaust gas recirculation line opens into the combustion air line downstream of at least one compressor of the compressor arrangement. It is thus preferably realized a high-pressure exhaust gas recirculation, in which the recirculated exhaust gas is supplied to the compressed combustion air. Especially here it is essential that in the donor cylinder a negative purge gradient is caused by damming the exhaust gas. In one embodiment, it is possible for the compressor assembly to include a low pressure compressor or a high pressure compressor. Preferably, it is then provided that the exhaust gas recirculation line - viewed in the direction of the combustion air flow - opens into the combustion air line downstream of the high-pressure compressor.

In another embodiment, it is possible that the exhaust gas recirculation line downstream of the low pressure compressor but opens upstream of the high pressure compressor in the combustion air duct.

In another embodiment, it is possible that a low-pressure exhaust gas recirculation is realized, wherein the combustion air line either has no compressor arrangement, or the exhaust gas recirculation line opens upstream of the compressor assembly in the combustion air line.

An internal combustion engine is preferred, which is characterized in that the exhaust gas aftertreatment element is designed as a catalyst element. Alternatively or additionally, it is possible that the exhaust gas aftertreatment element is designed as a particle filter. Particularly preferred is an embodiment in which the exhaust aftertreatment element is formed as an oxidation catalyst. This has the advantage, in particular with an arrangement of the exhaust gas aftertreatment element upstream of the second valve device, that reactive gases which comprise the exhaust gas are oxidized to be reactive, preferably inert gases. It is also possible that the exhaust aftertreatment element is formed as a combination of an oxidation catalyst and a particle filter.

An exemplary embodiment of the internal combustion engine is preferred in which the exhaust-gas aftertreatment element, viewed in the flow direction of the exhaust gas, is arranged directly in front of the first valve device. As a result, the accumulating effect of the exhaust aftertreatment element on the one hand and the first valve device on the other hand combine particularly effectively, whereby the advantages of the arrangement with regard to an effective stagnation of the exhaust gas and an efficient exhaust aftertreatment can be combined particularly effectively.

In one embodiment of the internal combustion engine is provided that the exhaust gas aftertreatment element - as seen in the flow direction of the exhaust gas - is arranged immediately in front of the second valve device. As a result, a particularly space-saving configuration is possible, and it is also an efficient cleaning of the recirculated exhaust gas allows.

Preferred is an embodiment of the internal combustion engine, which is characterized in that a first exhaust aftertreatment element is arranged upstream of the first valve device, wherein a second exhaust aftertreatment element is arranged upstream of the second valve device. As a result, the already described advantages of the various arrangements are combined. In this case, the first exhaust-gas aftertreatment element is preferably arranged immediately before the first valve device. The second exhaust aftertreatment element is preferably arranged directly in front of the second valve device.

An internal combustion engine is also preferred, which is characterized in that the exhaust manifold has a turbine arrangement with at least one turbine. Preferably, the at least one turbine is operatively connected to at least one compressor disposed in the combustion air duct, the compressor being driven by the turbine. In this way, an exhaust gas turbocharger arrangement is realized. The turbine arrangement is preferably arranged downstream of an opening of the fluid path of the at least one second cylinder in the exhaust manifold. Thus, the partial flow guided by the dispenser cylinders into the exhaust manifold can also be used to drive the turbine arrangement.

In one embodiment, it is possible for the turbine assembly to include a high pressure turbine and a low pressure turbine. Preferably, the high pressure turbine is operatively connected to a high pressure compressor in the combustion air duct to drive it. The low pressure turbine is preferably operatively connected to a low pressure compressor in the combustion air duct to drive it. In this way, a two-stage turbocharging is realized.

In a preferred exemplary embodiment of the internal combustion engine, a bypass line is provided in the region of at least one turbine of the turbine arrangement, through which exhaust gas can be conducted around the turbine so that the exhaust gas flow flowing in the bypass line does not drive the turbine. In this case, a turbine valve device is preferably provided, by means of which the exhaust gas flow flowing through the bypass line or through the turbine can be controlled and / or regulated.

In one exemplary embodiment of the internal combustion engine, a bypass line is preferably provided in at least one compressor of the compressor arrangement, through which combustion air can be conducted past the at least one compressor. In this case, a compressor valve device is preferably provided, by means of which a combustion air flow flowing through the bypass line or through the compressor can be controlled and / or regulated. Such a bypass line is particularly preferably provided for a high-pressure compressor when the compressor arrangement has a low-pressure compressor and a high-pressure compressor.

It is also preferred an internal combustion engine, which is characterized in that it is designed as a diesel engine. As already mentioned, in this context, an embodiment is particularly preferred in which the exhaust gas aftertreatment element is arranged upstream of the first valve device.

It is also preferred an embodiment of the internal combustion engine, which is designed as a gas engine, in particular as a lean-burn gas engine. As already stated, in this context, an embodiment is particularly preferred in which the exhaust gas aftertreatment element is arranged upstream of the second valve device.

An internal combustion engine is preferred, which is characterized by an engine control unit, by means of which the at least one first valve device and the second valve device can be activated. Preferably, the valve means can be controlled depending on an operating point of the internal combustion engine.

In a preferred exemplary embodiment of the internal combustion engine, the at least one first cylinder or at least one of the first cylinders can be switched off by the engine control unit as a function of an operating point of the internal combustion engine. It is particularly preferably possible to switch off a certain number of the first cylinders, preferably all first cylinders, ie non-donor cylinders, depending on the operating point. In particular, in an embodiment in which in the exhaust manifold no common exhaust aftertreatment element for all cylinders is provided more, can be turned off in this way, cylinders whose exhaust gas is not passed through an exhaust aftertreatment element, so that the emissions of the internal combustion engine can be reduced. In particular, it is provided that, depending on the operating point, only the at least one second cylinder, that is to say the at least one dispensing cylinder or the group of dispenser cylinders, is operated whose exhaust gas is passed via the exhaust gas aftertreatment element. If cylinders are switched off in part-load operation, this results in a better efficiency of the internal combustion engine at the same time. The exhaust gas of the active cylinders is then typically hotter, resulting in improved exhaust aftertreatment in the exhaust aftertreatment element, in particular improved conversion in an oxidation catalyst.

Finally, an internal combustion engine is preferred, which is characterized by a further exhaust gas aftertreatment element, preferably a further catalyst element, particularly preferably an oxidation catalyst, wherein the exhaust gas aftertreatment element is arranged in the exhaust manifold. Preferably, it is located downstream of the turbine assembly so that the exhaust pressure upstream of the turbine assembly is not reduced. The further exhaust aftertreatment element then has no negative effect on the performance of the turbine arrangement. With the aid of the further exhaust gas aftertreatment element, it is possible to after-treat the exhaust gas of all cylinders of the internal combustion engine, if this is necessary to fulfill emission requirements.

The invention will be explained in more detail below with reference to the drawing. Showing:

1 a schematic representation of a first embodiment of an internal combustion engine, and

2 a schematic representation of a second embodiment of an internal combustion engine.

1 shows a first embodiment of an internal combustion engine 1 in a schematic representation. This includes a total of four cylinders 3 , those over a combustion air line 5 Combustion air is supplied. It is an exhaust manifold 7 for the discharge of exhaust gas from the cylinders 3 intended. The term "exhaust manifold" is previously, not and not limited to an exhaust manifold used here, and for the entire part of the exhaust pipe from the junction of the individual cylinders 3 coming fluid paths to at least one exhaust, not shown.

Two first cylinders 9 Stand directly with the exhaust manifold 7 in fluid communication. There is no branch to an exhaust gas recirculation line 11 available. In particular, lead two fluid paths 13 each from one of the first cylinders 9 to the exhaust manifold 7 without the fluid paths 13 with the exhaust gas recirculation line 11 in a different way than necessary via the common exhaust manifold 7 in fluid communication. The exhaust gas, which from the first cylinders 9 is therefore not available for exhaust gas recirculation. Accordingly, the first cylinder 9 also referred to as non-donor cylinder.

The internal combustion engine 1 has two second cylinders 15 on, which are designed as a donor cylinder. In each case, a fluid path leads 17 from the second cylinders 15 to the exhaust gas recirculation line 11 so that from the second cylinders 15 emitted exhaust gas via the exhaust gas recirculation line 11 at least partially into the combustion air line 5 can be returned.

It is a fluid path 19 provided over which the second cylinder 15 with the exhaust manifold 7 in fluid communication. In the fluid path 19 is a first valve device 21 arranged by one of the second cylinders 15 emitted exhaust stream is divisible to a first, in the exhaust manifold 7 flowing partial flow and in a second, in the exhaust gas recirculation line 11 flowing partial flow. Preferably, the first valve means 21 designed as a flap, in particular as a donor cylinder flap. It is possible, via a choice of the functional position of the first valve device, the exhaust gas pressure in the fluid paths 17 . 19 to control and / or to regulate. Preferably, the first valve means 21 controlled by an unillustrated engine control unit, wherein their functional position is preferably continuously variable.

Is the first valve device 21 arranged in a first functional position, in which a fluid connection between the fluid path 19 and the exhaust manifold 7 is completely blocked, the entire of the second cylinders flows 15 coming Exhaust gas flow through the exhaust gas recirculation line 11 , In a second functional position, there is a fluid connection between the fluid path 19 and the exhaust pipe 7 preferably by the first valve device 21 completely released. In this case, preferably flows at least a majority of the second cylinders 15 emitted exhaust gas, preferably the entire exhaust gas flow into the exhaust manifold 7 , In an arrangement of the first valve device 21 between the first and the second functional position is that of the second cylinders 15 incoming exhaust stream preferably as already described divided into the first and the second partial flow.

In the exhaust gas recirculation line 11 is a second valve device 23 arranged, through which a flow cross-section of the exhaust gas recirculation line 11 preferably continuously, that is infinitely variable. The second valve device is preferred 23 as a flap, in particular as an exhaust gas recirculation flap formed. Preferably, it can be controlled by an engine control unit in particular operating point-dependent.

It is possible that the second valve device 23 is completely closed in a first functional position, so that no exhaust gas through the exhaust gas recirculation line 11 can flow. This functional position is preferably assumed when the first valve device 21 is completely open. In this case, the whole of the second cylinders 15 incoming exhaust gas flow into the exhaust manifold 7 directed. In a second functional position, the second valve device 23 preferably fully open, so that the exhaust gas substantially unhindered by the exhaust gas recirculation line 11 can flow. By controlling functional positions between the first and second functional position of the second valve device 23 can an exhaust gas recirculation rate, in particular at a fixed functional position of the first valve device 21 be varied. Particularly preferred are the first valve device 21 and the second valve device 23 operated jointly depending on the operating point of an engine control unit, with their functional positions are coordinated with each other, on the one hand, a pressure in the exhaust gas recirculation line 11 upstream of the second valve means 23 and on the other hand to set an exhaust gas recirculation rate.

In the illustrated embodiment of the internal combustion engine 1 is in the fluid path 19 upstream of the first valve means 21 , in particular immediately before the same an exhaust aftertreatment element 25 arranged, which is preferably formed as an oxidation catalyst. Through the exhaust aftertreatment element 25 the exhaust gas is in addition to the first valve device 21 dammed up to a negative purge gradient for efficient exhaust gas recirculation into the combustion air duct 5 build. The built-up in this area pressure is thus not exclusively by the first valve device 21 and thus formed by a passive element, but it is used at the same time useful for exhaust aftertreatment.

In the illustrated embodiment of the internal combustion engine 1 is not another exhaust aftertreatment element in the exhaust manifold 7 more provided because already the first exhaust aftertreatment element 25 sufficient for the internal combustion engine 1 Total compliance with the applicable emission limit values. This is the exhaust back pressure for the first cylinder 9 less than a conventional internal combustion engine, which is an exhaust aftertreatment element in the exhaust manifold 7 having. In this way, charge exchange losses can be minimized. The here by the first exhaust aftertreatment element 25 built-up exhaust pressure is in the range of the second cylinder 15 anyway required, so that no additional charge exchange losses incurred by exhaust aftertreatment at this point.

In particular, when the first exhaust aftertreatment element 25 is designed as an oxidation catalyst is preferably no further oxidation catalyst in the exhaust manifold 7 intended. In such an embodiment, however, it is possible that in the exhaust manifold 7 For example, a particulate filter or another, additional exhaust aftertreatment element, for example, a selective catalyst for nitrogen oxide reduction is provided.

It is also possible that the first exhaust aftertreatment element 25 is designed as a combined oxidation catalyst with a particle filter or as a particle filter with a catalytic coating. In this case, an embodiment is possible in which in the exhaust pipe 7 neither an oxidation catalyst nor a particle filter is provided. It is also an embodiment possible in which no exhaust aftertreatment element in the exhaust manifold 7 is provided.

At the in 1 illustrated embodiment is a second exhaust aftertreatment element 27 in the exhaust gas recirculation line 11 upstream of the second valve means 23 , in particular immediately before the second valve device 23 arranged. The second exhaust aftertreatment element 27 is preferably formed as an oxidation catalyst. Alternatively or additionally, it is possible that the second exhaust aftertreatment element 27 is designed as a particle filter. With the help of the second exhaust aftertreatment element 27 this will be in the combustion air line 5 recirculated exhaust gas cleaned, in particular, reactive gases such as unburned hydrocarbons, carbon monoxide and nitrogen oxides oxidized to inert gases such as carbon dioxide, water vapor and nitrogen dioxide. Due to the increased proportion of inert gas in the recirculated exhaust gas, a knock limit of the internal combustion engine 1 extended. Is the second exhaust aftertreatment element 27 alternatively or additionally formed as a particle filter, a concentration of particles in the recirculated exhaust gas is also reduced.

Preferably, in the exhaust gas recirculation line 11 an exhaust gas recirculation cooling device 29 arranged, with the help of which in the combustion air line 5 recirculated exhaust gas can be cooled.

In the combustion air line 5 is a compressor arrangement 31 arranged at the in 1 illustrated embodiment, a low-pressure compressor 33 and a high pressure compressor 35 having. It is therefore possible in the combustion air line 5 to compress flowing combustion air in two stages. Here is a bypass to bypass the high pressure compressor 35 provided, or in the illustrated embodiment is the high pressure compressor 35 in a bypass 37 arranged. It is a compressor valve device 39 provided by the preferably operating point-dependent and particularly preferably driven by the engine control unit through a high-pressure compressor 35 flowing part of the combustion air can be controlled and / or regulated. Upstream of the high pressure compressor 35 is a first combustion air cooler 41 arranged by which in the low pressure compressor 33 compressed and thus heated combustion air before entering the high-pressure compressor 35 can be cooled. In the illustrated embodiment, the first combustion air cooler 41 also in the bypass 37 arranged. Downstream of both the low pressure compressor 33 as well as the high pressure compressor 35 and in particular also downstream of the compressor valve device 39 is a second combustion air cooler 43 arranged in which the compressed combustion air can be cooled in total. This makes it possible to fill the cylinder 3 to increase.

The exhaust gas recirculation line 11 opens - seen in the direction of the combustion air flow - downstream of the high-pressure compressor 35 , so high pressure side, in the combustion air line 5 one. It is therefore in the illustrated embodiment of the internal combustion engine 1 realizes a high pressure exhaust gas recirculation.

In the exhaust manifold 7 is a turbine arrangement 45 with a high-pressure turbine 47 and a low-pressure turbine 49 arranged. The high pressure turbine 47 is preferably over a shaft 51 with the high pressure compressor 35 working to drive this. The low pressure turbine 49 is preferably over a shaft 53 with the low pressure compressor 33 working to drive this. Overall, a two-stage turbocharging is realized.

In the illustrated embodiment, there are two turbine valve devices 55 . 57 in bypass lines 59 . 61 arranged, wherein the turbine valve devices are preferably controlled by an engine control unit in particular operating point dependent to at least a portion of the exhaust gas flow to the high pressure turbine as needed 47 and / or at the low pressure turbine 49 to be able to pass by.

The fluid path 19 opens upstream of the turbine assembly 45 into the exhaust manifold 7 one. In particular, this is in the exhaust gas recirculation line 11 introduced exhaust gas upstream of the turbine assembly 45 the fluid paths 17 taken, ie on a high pressure side of the exhaust system.

By an engine control unit operating point dependent, the first cylinder 9 shut off, only the second cylinders are left 15 active, reducing the efficiency of the internal combustion engine 1 is increased in partial load operation. In addition, in this case, the entire in the exhaust pipe 7 introduced exhaust gas through the first exhaust aftertreatment element 25 Guided, so that in this mode of operation particularly favorable emission levels of the internal combustion engine 1 result. At the same time, the exhaust gas is hotter than when all cylinders are in the same load point 3 would operate, so that a better after treatment in the exhaust aftertreatment element 25 results. This in turn has a positive effect on the total emissions of the internal combustion engine 1 out.

2 shows a schematic representation of a second embodiment of the internal combustion engine 1 , Identical and functionally identical elements are provided with the same reference numerals, so that reference is made to the preceding description. This in 2 illustrated embodiment of the internal combustion engine 1 differs essentially from the in 1 illustrated embodiment that here is a number of donor cylinder is variable. It's just a first cylinder 9 provided by the fluid path 13 immediately without branching to the exhaust gas recirculation line 11 with the exhaust manifold 7 is in fluid communication. The remaining cylinders 1.15 . 2.15 . 3.15 are via fluid paths 1.17 . 2.17 . 3.17 respectively 1.19 . 2.19 . 3.19 each with first valve means 1.21 . 2.21 . 3.21 connected by that of the cylinders 1.15 . 2.15 . 3.15 incoming exhaust gas flow either into the exhaust manifold 7 or in the exhaust gas recirculation line 11 can be introduced. Preferably, in particular continuously adjustable intermediate positions are possible with which the exhaust gas streams can be divided into corresponding partial streams. Preferably, it is possible to set the number of dispenser cylinders operating point dependent. For example, it is possible in an operating state that only the cylinder 1.15 works as a donor cylinder, while the exhaust of the cylinder 2.15 and 3.15 completely in the exhaust manifold 7 is directed. The cylinders 2.15 and 3.15 can be switched on as needed independently or together as a donor cylinder. It is also possible to operate in which none of the cylinders 1.15 . 2.15 . 3.15 acts as a donor cylinder.

Each of the cylinders 1.15 . 2.15 . 3.15 is upstream of the valve device 1.21 . 2.21 . 3.21 a first exhaust aftertreatment element 1.25 . 2.25 . 3.25 assigned.

In the illustrated embodiment is in the exhaust manifold 7 another exhaust aftertreatment element 63 arranged. This can be designed as an oxidation catalyst, as a particle filter or as a combined particle filter with a catalytic coating. It is also possible that the further exhaust aftertreatment element 63 is designed as SCR catalyst. It is also an embodiment possible, which otherwise according to 2 is formed, but no further exhaust aftertreatment element 63 includes.

Overall, it turns out that the internal combustion engine 1 According to one exemplary embodiment, an exhaust gas pressure to be built up in the region of dispenser cylinders is used advantageously for exhaust gas aftertreatment and thus has reduced charge exchange losses and thus improved efficiency. According to another embodiment, purified exhaust gas is introduced into the combustion air duct 5 returned, so that the knock limit of the internal combustion engine 1 is extended. In particular, an inert gas content in the recirculated exhaust gas is increased. It also turns out that these embodiments can be advantageously combined with each other.

QUOTES INCLUDE IN THE DESCRIPTION

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Cited patent literature

• DE 19960998 C1 [0002]

Claims (10)

Internal combustion engine ( 1 ) with at least one first cylinder ( 9 ), at least one second cylinder ( 15 ), a combustion air line ( 5 ) for supplying combustion air to the cylinders ( 3 ) and with an exhaust manifold ( 7 ) for the discharge of exhaust gas from the cylinders ( 3 ), and with an exhaust gas recirculation line ( 11 ), wherein the at least one first cylinder ( 9 ) immediately without branching to the exhaust gas recirculation line ( 11 ) with the exhaust manifold ( 7 ) is in fluid communication, wherein in a fluid path ( 19 ) of the at least one second cylinder ( 15 ) to the exhaust manifold ( 7 ) a first valve device ( 21 ) is arranged, through which one of the at least one second cylinder ( 15 ) emitted exhaust gas stream is divisible to a first, in the exhaust manifold ( 7 ) flowing partial flow and a second, in the exhaust gas recirculation line ( 11 ) to the combustion air line ( 5 ) flowing partial flow, wherein in the exhaust gas recirculation line ( 11 ) a second valve device ( 23 ) is arranged through which a flow cross-section of the exhaust gas recirculation line ( 11 ) is variable, characterized in that upstream of at least one of the first and the second valve device ( 21 . 23 ) an exhaust gas aftertreatment element ( 25 . 27 ) is arranged. Internal combustion engine ( 1 ) according to claim 1, characterized in that the combustion air duct ( 5 ) a compressor arrangement ( 31 ) with at least one compressor ( 33 . 35 ), wherein the exhaust gas recirculation line ( 11 ) downstream of at least one compressor ( 33 . 35 ) of the compressor assembly ( 31 ) in the combustion air line ( 5 ). Internal combustion engine ( 1 ) according to one of the preceding claims, characterized in that the exhaust gas aftertreatment element ( 25 . 27 ) is formed as a catalyst element, preferably as an oxidation catalyst. Internal combustion engine ( 1 ) according to one of the preceding claims, characterized in that the exhaust gas aftertreatment element ( 25 ) immediately before the first valve device ( 21 ) is arranged. Internal combustion engine ( 1 ) according to one of the preceding claims 1 to 3, characterized in that the exhaust aftertreatment element ( 27 ) immediately before the second valve device ( 23 ) is arranged. Internal combustion engine ( 1 ) according to one of the preceding claims, characterized in that a first exhaust gas aftertreatment element ( 25 ) upstream of the first valve device ( 21 ), preferably immediately before the first valve device ( 21 ), wherein a second exhaust aftertreatment element ( 27 ) upstream of the second valve device ( 23 ), preferably immediately before the second valve device ( 23 ) is arranged. Internal combustion engine ( 1 ) according to one of the preceding claims, characterized in that the exhaust manifold ( 7 ) a turbine arrangement ( 45 ) with at least one turbine ( 47 . 49 ), wherein the turbine arrangement ( 45 ) preferably downstream of an opening of the fluid path ( 19 ) of the at least one second cylinder ( 15 ) into the exhaust manifold ( 7 ) is arranged. Internal combustion engine ( 1 ) according to one of the preceding claims, characterized in that the internal combustion engine ( 1 ) is designed as a diesel engine or as a gas engine, in particular a lean-burn gas engine. Internal combustion engine ( 1 ) according to one of the preceding claims, characterized by an engine control unit, by which the at least one first valve device ( 21 ) and the second valve device ( 23 ) preferably dependent on an operating point of the internal combustion engine ( 1 ), wherein preferably by the engine control unit of the at least one first cylinder ( 9 ) depending on an operating point of the internal combustion engine ( 1 ) can be switched off. Internal combustion engine ( 1 ) according to one of the preceding claims, characterized by a further exhaust gas aftertreatment element ( 63 ), preferably a catalyst element in the exhaust manifold ( 7 ) preferably downstream of the turbine assembly ( 45 ) is arranged.

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