DE102010037649B4 - System for conducting charge air and exhaust gas to an internal combustion engine, method for operating such a system and internal combustion engine with such a system - Google Patents

Abstract

System for conducting charge air and exhaust gas to an internal combustion engine, which relative to a combustion chamber (2) of the engine (1) has a supply side (29) for the supply of charge air to a supply line (31) and a discharge side (30) for the removal of exhaust gas with a discharge line (32), wherein the system for conducting charge air and exhaust gas (28) at least a first exhaust gas recirculation (11) having a return line (16) through which exhaust gas from the discharge side (30 to the feed side (31) and wherein a return line (16) is connected in a region behind a fresh air inlet (35) to the supply line (31) to form an inlet of exhaust gas (18) and wherein the return line (16) communicates with the Discharge line (32) is connected in an area behind a turbine (6), and wherein the system for conducting charge air and exhaust gas (28) has a second exhaust gas recirculation (12) with a return line (17), and wherein the first Abg As a result, in the supply line (31) between the fresh air inlet (35) and the second exhaust gas recirculation (12) for returning high-pressure exhaust gas (26) are formed Inflow of low-pressure exhaust gas (18) is a controllable throttle (22) for opening or closing the fresh air supply (9) is arranged, and that the controllable throttle (22) is adapted to the fresh air supply (9) in a state of the engine (1) to close, in which a per piston stroke in a combustion chamber (2) burned amount of fuel (QFIN) is very low or equal to zero.

Description

The invention relates to a system for conducting charge air and exhaust gas to an internal combustion engine. It is known in the art to provide internal combustion engines with a system for conducting charge air to carry charge air from a fresh air inlet to an engine intake. The charge air is possibly introduced under pressure into a combustion chamber of the engine and burned there together with an attached fuel. This produces exhaust gas which is exhausted from the combustion chamber through an engine exhaust and through a system for passing exhaust gas to an exhaust gas outlet or exhaust. It is also known to provide such systems with an exhaust gas recirculation, which recirculates exhaust gas from a discharge side of the engine to a supply side, where the exhaust gas is added to the charge air. Previously known systems for conducting charge air and exhaust gas have the disadvantage that in an operating condition of the engine, in which only a very small amount of fuel is burned with high oxygen excess in the combustion chamber, the system for conducting charge air and exhaust gas is flooded with oxygen-rich gas , The oxygen content contained in the charge air reduces only slightly in the combustion chamber. In this case, the oxygen content on the supply side and on the discharge side increases sharply and the exhaust gas recirculation is also filled with a gas having a high oxygen concentration.

In a change from such operating state with low fuel combustion in an operating state in which a larger amount of fuel is burned in the combustion chamber, thus a charge air with relatively high oxygen content, which consists for example only of fresh air, introduced into the combustion chamber. As a result, an exhaust gas having a high emission rate, in particular with a high proportion of nitrogen oxides (NOx) is generated after the change of the operating state of a fuel-lean or fuel-free operation to a higher fuel combustion operation over a certain period of time in the combustion chamber.

The production of nitrogen oxides depends largely on the level of oxygen content in the charge air. The higher the oxygen content, the more nitrogen oxides can be produced in the combustion process in the combustion chamber. Thus, it is common in known systems that when switching from a load-free operation or coasting operation of the engine to a load-loaded operation or train operation, a temporary increase in pollutant emissions and in particular the nitrogen oxide emission arises.

DE 10 2004 044 893 D1 discloses a low pressure exhaust gas recirculation device and a method of operating the exhaust gas recirculation device for an internal combustion engine. In the air supply line, an adjustable throttle is arranged, by which it is possible to set a high exhaust gas recirculation rate of up to 70%, even at zero pressure or with low pressure applied recirculated exhaust gas. A complete closure of the throttle in the air supply is not provided. The DE 10 2004 044 893 D1 does not deal with the time at which the throttle is actuated.

From the DE 601 05 658 T2 discloses a system for controlling a diesel engine with direct injection, which reduces combustion noise and avoids misfiring under no-load conditions. A throttle valve is provided in the intake of the engine. The system incorporates high pressure exhaust gas recirculation and it is recommended that the exhaust gas recirculation valve be brought to a closed state in idle mode when a control operation to reduce the intake air amount is performed.

WO 2005/033496 A1 discloses a method for operating an internal combustion engine, with which by using the HCLI combustion method from the lower part-load range to the full-load range minimum nitrogen oxide emissions should be achieved. The exhaust gas recirculation rate should be variable between about 0% and 70% or 80%. High pressure exhaust gas recirculation directs exhaust gas from an exhaust line to an intake line. Low pressure exhaust gas recirculation directs exhaust gas from the exhaust passage downstream of a particulate filter into an intake passage. Fresh air can flow through the intake pipe via a compressor into the intake pipe and further into a combustion chamber of the internal combustion engine. In order to avoid NOx spikes during re-insertion in the case of short thrust phases, it is advantageous if, during overrun operation, a throttle valve arranged in the intake line is closed and an exhaust gas recirculation valve is opened.

DE 11 2007 003 296 T5 discloses a technique for combustion compensation for engines operating on the HCCI combustion process. The engine has high pressure and low pressure exhaust gas recirculation. Fresh air passes through a throttle control valve before entering a fresh air supply passage. The throttle control valve may still be restricted from a fully throttled position allows a certain amount of fresh air to enter the system, to be controlled to an unrestricted fully open position.

It is an object of the present invention to provide a system for directing charge air and exhaust gas to an internal combustion engine, which is reduced in a change from an operating condition with combustion of a very small amount of fuel to an operating condition with combustion of a larger amount of fuel pollutant emissions. It is a further object of the present invention to provide a method for operating such a system for conducting charge air and exhaust gas and an internal combustion engine with such a system for conducting charge air and exhaust gas.

The invention solves this problem with the features in the independent claims.

The system according to the invention for conducting charge air and exhaust gas to an internal combustion engine has a supply line on the supply side and a discharge line on the discharge side. The supply line extends from a fresh air inlet to an engine inlet and may consist of several parts. The discharge line extends from an engine outlet to an exhaust outlet or exhaust and may also consist of several parts.

In the system for conducting charge air and exhaust gas, gas may flow through the supply line in a direction from a fresh air inlet toward an engine intake and through the discharge line from an engine exhaust to an exhaust gas outlet. In the following, terms such as "behind" or "before" are referred to in this flow direction for indicating positions in the supply pipe or the discharge pipe.

The system includes at least one exhaust gas recirculation configured to recirculate exhaust gas from the discharge side to the supply side. The exhaust gas recirculation system comprises a return line, which is connected to the discharge line on the one hand in an area behind the engine outlet and on the other hand in a region in front of the engine inlet to the supply line. At the connection point of the return line and the supply line, an inflow for recirculated exhaust gas is thereby formed, from which the recirculated exhaust gas can mix with the already existing gas in the supply line. This inflow of exhaust gas is in an area of the supply line between the fresh air inlet and the engine inlet.

The system according to the invention for conducting charge air and exhaust gas has a controllable throttle for opening or closing the fresh air supply in the supply line between the fresh air inlet and the inflow of exhaust gas.

The controllable throttle makes it possible to throttle the amount of fresh air flowing into the supply line and, if necessary, to reduce it to zero. This makes it possible to mix the charge air supplied to the combustion chamber at the engine inlet by controlling the throttle and controlling the flow rates of the one or more exhaust gas recirculations to any proportions of fresh air and one or more types of recirculated exhaust gas.

In particular, it is possible, in the case of a closed state of the controllable throttle, to form the charge air supplied to the engine intake exclusively from one or more types of recirculated exhaust gas. This can advantageously be achieved that, in an operating condition of the engine, in which only a very small amount of fuel is burned in a combustion chamber, a circuit is formed in the system for conducting charge air and exhaust gas, in which a large part of the exhaust gas or total exhaust gas is recirculated from the discharge side to the supply side. In this way, an oxygen content of the charge air supplied to the engine intake can be kept low even in such an operating state with low fuel combustion over a longer period. The system for conducting charge air and exhaust gas is thereby not flooded with fresh air. Even with a change of the operating state of a no-load operation or overrun operation to such an operating condition in which again a larger amount of fuel is burned in the combustion chamber, thus a charge air can be burned with low oxygen content in the combustion chamber immediately, so in a combustion process Pollutant emissions and in particular an emission of nitrogen oxides (NOx) are kept low.

An operating state with low fuel combustion may mean that in a combustion chamber of the engine, possibly over a few piston strokes, only a small amount of added fuel or no added fuel at all is burned. The fuel can be added in any known manner.

In a common-rail diesel engine with direct injection in a vehicle, which is operated in a normal driving cycle, can be achieved by the inventive system for conducting charge air and exhaust gas, a reduction of pollutant emission and / or nitrogen oxide emissions of 3 to 4%. In the case of an operating characteristic of an internal combustion engine in which very frequent changes occur between the aforementioned operating states, the emission and emission reduction can be even more pronounced.

The controllable throttle may be configured to regulate the flow rate of fresh air flowing in through the air inlet. As a result, an even more accurate and faster adjustment of the composition of the charge air can advantageously be achieved. It is particularly possible to produce a mixture of the charge air, which has only a small proportion of fresh air. This makes it possible to positively influence a combustion stability and smoothness of the engine and to support a quality control of the engine control. This can have an advantageous effect on the response of the internal combustion engine and contribute in a load change to a fast availability of the output power of the engine.

The system for conducting charge air and exhaust gas may preferably have a compressor on the supply side and a turbine on the discharge side. This makes it possible to pressurize the charge air supplied to the engine intake and thus increase a charge amount of the charge air in the combustion chamber per piston stroke. Via the turbine, an energy stored after combustion in an increased pressure of the exhaust gas can be absorbed and utilized. Thus, it is possible to produce a high output power of the internal combustion engine, even with a low oxygen content in the charge air, which has a low pollutant and nitrogen oxide emissions and works very efficiently.

The system for conducting charge air and exhaust gas to an internal combustion engine may preferably be operated with a method in which, in an operating condition of the engine in which the amount of fuel burned per piston stroke in the combustion chamber is very low or zero, a fresh air supply by actuation of the controllable throttle reduced or closed and a flow rate of recirculated exhaust gas is opened. This makes it possible that the oxygen content in the charge air is kept low even in an operating state of the engine with low fuel combustion over a longer period of time. In particular, it is possible, even during such an operating state, to regulate the oxygen content in the charge air by controlled addition of fresh air and, if necessary, to set it to a desired value.

It may be particularly advantageous that a flow rate of recirculated exhaust gas is adjusted so that forms a cycle between the discharge side and the supply side via an exhaust gas recirculation, in which is discharged from an engine exhaust (discharged) exhaust gas to an engine inlet , with no or only a very small amount of fresh air is supplied. In this way, it is possible that the entire guided in the system for guiding charge air and exhaust gas having an oxygen content, which is less than the oxygen content of fresh air over a longer period. In this case, it is possible, in particular, for a recirculated exhaust gas having a low oxygen content to flow in the lines of an exhaust gas recirculation, so that a particularly rapid regulation of the mixing ratio of the charge air is possible even when the operating state changes.

Furthermore, it may be advantageous that the aforementioned circuit is formed only via an exhaust gas recirculation, in which filtered and / or low-pressure exhaust gas is recirculated. In this way, it is possible that a proportion of pollutants and / or particles in the charge air and thus in the combustion chamber is kept low, so that a mechanical or chemical stress on components in the region of the combustion chamber, such as an injector is kept low.

It is further object of the invention to provide an internal combustion engine with a system for conducting charge air and exhaust gas, wherein in the manner described above, a regulation of the oxygen content in the charge air is possible even in an operating condition of the engine, in which a quantity of fuel burned in the combustion chamber is very low or zero. Such an internal combustion engine may be a diesel engine.

In the dependent claims further advantageous embodiments of the invention are shown.

The invention is illustrated by way of example and schematically in the drawings. Show it:

1 a schematic diagram of a system for directing charge air and exhaust gas to an internal combustion engine;

2 a representation of the possible gas flows of charge air and exhaust gas in a system according to 1 ;

3 FIG. 2 is an illustration of a preferred gas cycle in the system. FIG 1 in an operating condition of the engine with little or no fuel combustion;

4 : Characteristics for the operation of an internal combustion engine with a system according to the invention and a comparison system.

The invention relates to a system for conducting charge air and exhaust gas ( 28 ) on an internal combustion engine ( 1 ). Such a system ( 28 ) is in 1 shown schematically. Representative of the internal combustion engine ( 1 ) is a cylinder with a piston ( 23 ) shown in a combustion chamber ( 2 ) can compress trapped gas. The internal combustion engine can have any number of cylinders, for example 4, 6 or 8 cylinders. Any other number of cylinders is possible.

Via an engine intake ( 33 ) can charge air via a valve ( 3 ) in the combustion chamber ( 2 ). The internal combustion engine ( 1 ) may be, for example, a direct injection engine and an injector ( 4 ), via the fuel directly into the combustion chamber ( 2 ) can be injected. The gas in the combustion chamber ( 2 ) can be connected via a valve ( 3 ' ) through an engine outlet ( 34 ) to a discharge page ( 30 ). The system for conducting charge air and exhaust gas thus has with respect to a combustion chamber ( 2 ) of the motor ( 1 ) a feed page ( 29 ) for the supply of charge air with a supply line ( 31 ) and a rejection page ( 30 ) for the removal of exhaust gas with a discharge line ( 32 ) on.

The term "charge air" is understood to mean a gas which is passed through an engine intake ( 33 ) in a combustion chamber ( 2 ) of the internal combustion engine ( 1 ) is introduced. The charge air can be composed of several components. These are one through a fresh air inlet ( 35 ) supplied fresh air ( 27 ) and one or more types of recirculated exhaust gas ( 25 . 26 ). The term "charge air" refers to a gas in the supply line ( 31 ) and in particular a gas in an engine intake or in a combustion chamber prior to a combustion process. Exhaust gas is understood to mean a gas which is emitted from a combustion chamber ( 2 ) through an engine outlet ( 34 ) is fed. The term exhaust gas can be a gas in the discharge line ( 32 ) and / or a gas in a recirculation line ( 16 . 17 ) describe. For better distinguishability, an exhaust gas in a return line ( 16 . 17 ) as recirculated exhaust gas ( 25 . 26 ) designated.

The system for conducting charge air and exhaust gas ( 28 ) has at least one exhaust gas recirculation ( 11 . 12 ) with a return line ( 16 . 17 ) on. In 1 is an example of a system ( 28 ) with two exhaust gas recirculations ( 11 . 12 ). However, the system may only have one or another number of exhaust gas recirculations.

The supply line ( 31 ) may be, for example, a pipe which optionally divides into a plurality of segments and which is designed to charge air from a fresh air inlet ( 35 ) to the engine intake ( 33 ) respectively. In the course of the supply line ( 31 ) between fresh air intake ( 35 ) and engine intake ( 33 ) may be arranged other components and connections to other lines.

A discharge line ( 32 ) may also preferably be a tube and be adapted to exit from the engine outlet ( 34 ) led out exhaust gas to an exhaust outlet ( 36 ) or exhaust. Also in the course of the discharge line ( 32 ) Further components and connections to other lines can be arranged. Supply line ( 31 ) and discharge line ( 32 ) may alternatively or additionally be formed in whole or in part in other ways, such as a hose or flexible conduit. The supply line ( 31 ) and the discharge line ( 32 ) can each consist of several parts or pieces.

An exhaust gas recirculation ( 11 . 12 ) has a return line ( 16 . 17 ) on. A return line ( 16 . 17 ) is adapted to exhaust gas from a discharge side ( 30 ) of the engine to a feed side ( 29 ) respectively. In 1 is for example a first exhaust gas recirculation ( 11 ), which is a return line ( 16 ) connected to the supply line ( 31 ) in an area behind a fresh air inlet ( 35 ) connected is. At the junction is an inflow of exhaust gas ( 18 ) educated.

The system for conducting charge air and exhaust gas ( 28 ) preferably points to the feed side ( 29 ) a compressor ( 5 ) on. It may possibly additionally or alternatively on the discharge side ( 30 ) a turbine ( 6 ) exhibit. The compressor ( 5 ) is preferably in a region of the supply line ( 31 ) between the inflow of exhaust gas ( 18 ) and an engine intake ( 33 ) arranged. The turbine ( 6 ) is on a rejection page ( 30 ), preferably in a region between an engine outlet ( 34 ) and an exhaust outlet ( 36 ) arranged. The compressor ( 5 ) serves to pressurize charge air. The turbine ( 6 ) serves to relax pressurized exhaust gas while absorbing the energy stored in the pressure. The turbine ( 6 ) may preferably be a controllable turbine in which a degree of relaxation of the exhaust gas and / or energy transfer is adjustable, for example, by adjusting an angle of attack of the turbine blades. The compressor ( 5 ) and the turbine ( 6 ) can be connected to each other via a rigid shaft (not shown). Alternatively, the compressor ( 5 ) and the turbine ( 6 ) be operated mechanically independently of each other. The compressor ( 5 ) may alternatively or additionally have a separate drive. This can be, for example, an electric motor.

The system according to the invention for conducting charge air and exhaust gas ( 28 ) points in the supply line ( 31 ) between the fresh air intake ( 35 ) and the inflow of exhaust gas ( 18 ) a controllable throttle ( 22 ) for opening or closing the fresh air supply ( 9 ) on. The throttle ( 22 ) may be formed in any way. It can be designed for example as a throttle valve, as a sliding door or as a controllable valve. In 1 is an example of a controllable throttle ( 22 ) in the form of a flap, shown here in the closed position. In the closed position, the throttle ( 22 ) the fresh air supply ( 9 ) preferably completely close. Alternatively, the throttle ( 22 ) allow in the closed state, the inflow of a very small amount of fresh air.

The system for conducting charge air and exhaust gas ( 28 ) in the embodiment of 1 has a second exhaust gas recirculation ( 12 ) with a return line ( 17 ) on. The second exhaust gas recirculation ( 12 ) may alternatively or in addition to the first exhaust gas recirculation ( 11 ) be provided. The second exhaust gas recirculation ( 12 ) leads exhaust gas from an area in the discharge line ( 32 ) between an engine outlet ( 34 ) and a turbine ( 6 ) to the feed side ( 29 ). The return line ( 17 ) is preferred on the feed side ( 29 ) with the supply line ( 31 ) in an area behind a compressor ( 5 ) and in front of an engine intake ( 33 ) connected. In this way it is possible with the second exhaust gas recirculation ( 12 ) an exhaust gas which is under a high pressure, from the discharge side ( 30 ) to the feed side ( 29 ). The exhaust gas recirculation ( 12 ) can a cooler ( 15 ) and a bypass ( 13 ) and be formed in a known manner. The flow rate of exhaust gas through the return line ( 17 ) can be controlled by a control valve ( 21 ) be regulated. At the junction of return line ( 17 ) and supply line ( 31 ) is an inflow of exhaust gas ( 19 ) educated.

The system for conducting charge air and exhaust gas ( 28 ) can charge a charge air cooler ( 7 ). The intercooler ( 7 ) is on the feed side ( 29 ) in the region of the supply line ( 31 ) arranged. It may preferably be located in a region of the supply line ( 31 ) behind a compressor ( 5 ) and before an inflow of exhaust gas ( 19 ) can be arranged.

The system for conducting charge air and exhaust gas ( 28 ) can also be found on the Withdrawal page ( 30 ) a particle filter ( 8th ) exhibit. Such a particle filter ( 8th ) is known in principle. The particle filter ( 8th ) is on the collection page ( 30 ) in an area of the loading line ( 32 ) arranged. It is particularly preferred in an area of the discharge line ( 32 ) behind a turbine ( 6 ) and before a connection point of the discharge line ( 32 ) with the return line ( 16 ) arranged. Accordingly, the first exhaust gas recirculation ( 11 ) preferably filtered exhaust gas from an area behind a particulate filter ( 8th ) to the feed side ( 29 ).

The first return line ( 16 ) can preferably with the discharge line ( 32 ) in an area behind a turbine ( 6 ), so that the first exhaust gas recirculation ( 11 ) a low pressure exhaust gas to the supply side ( 29 ). As in 1 shown, the return line ( 16 ) of the first exhaust gas recirculation ( 11 ) in particular with the discharge line ( 32 ) in an area behind the turbine ( 6 ) and behind a particle filter ( 8th ). In such a case, the first exhaust gas recirculation ( 11 ) to form a filtered and low pressure exhaust gas to a supply side ( 29 ). The first exhaust gas recirculation ( 11 ) may also be formed in a known manner. It may preferably be in the region of a return line ( 16 ) a cooler ( 14 ) for cooling recirculated exhaust gas ( 25 ) and for the regulation of a flow rate of exhaust gas through the return line ( 16 ) a control valve ( 20 ) exhibit.

In 2 is exemplified in which way charge air and exhaust gas in principle by a system for conducting charge air and exhaust gas ( 28 ) can flow. On a feed page ( 29 ) can fresh air ( 27 ) through a fresh air inlet ( 35 ) into the supply line ( 31 ). Thus, in the area of the air intake ( 35 ) a fresh air supply ( 9 ) educated. At an inflow of exhaust gas ( 18 ), a recirculated exhaust gas ( 25 ) from the return line ( 16 ) into the supply line ( 31 ). The recirculated exhaust gas ( 25 ) can differ from the inflow of exhaust gas ( 18 ) with the in the supply line ( 31 ) flowing fresh air ( 27 ) mix. The possibly mixed gas can through the supply line ( 31 ) to an engine intake ( 33 ). Preferably, the gas may be passed through a compressor ( 5 ) and a charge air cooler ( 7 ). At an inflow of exhaust gas ( 19 ), another recirculated exhaust gas ( 26 ) from a second exhaust gas recirculation ( 12 ) into the supply line ( 31 ) be initiated.

In one area of the supply line ( 31 ) behind an inflow of exhaust gas ( 19 ), a supplied exhaust gas ( 26 ) from the return line ( 17 ) with the from the front areas of the supply line ( 31 ) mixed gas. The at the engine inlet ( 33 ) present mixed gas may thus consist of one or more components, in particular fresh air ( 27 ) and one or more types of recirculated exhaust gas ( 25 . 26 ).

Through the controllable throttle ( 22 ) it is possible to calculate a flow rate of fresh air ( 27 ) to regulate. By means of a control valve ( 20 ), the flow rate of recirculated exhaust gas ( 25 ) in the first exhaust gas recirculation ( 11 ) and via a control valve ( 21 ), the flow rate of recirculated exhaust gas ( 26 ) in the second exhaust gas recirculation ( 12 ) are regulated. Depending on the flow rate setting, this can be done at the engine inlet ( 33 ) present gas from fresh air ( 27 ) or from a first recirculated exhaust gas ( 25 ) or from a second recirculated exhaust gas ( 26 ) consist. It may also be mixed from any composition of one, two or three of said components, ie in a mixture of fresh air ( 27 ) and / or first recirculated exhaust gas ( 25 ) and / or second recirculated exhaust gas ( 26 ). The composition of the gas can be adjusted by specifying the respective flow rates to any proportions and precisely.

3 shows by way of example a gas flow through the system for conducting charge air and exhaust gas ( 28 ) on the internal combustion engine ( 1 ) in an operating condition of the engine ( 1 ), in which one per piston stroke in a combustion chamber ( 2 ) burned amount of fuel is very low or zero. How out 3 is apparent, the controllable throttle ( 22 ) in such an operating condition preferably closable. This allows a flow rate of fresh air to be regulated to a very low value or to zero. This results in a cycle of charge air and exhaust gas in the system ( 28 ), from which the engine outlet ( 34 ) exhausted gas through the particulate filter ( 8th ) is filtered and via the first exhaust gas recirculation ( 11 ) into the supply line ( 31 ) and via the engine intake ( 33 ) back into the combustion chamber ( 2 ). In the in 3 sketched case is the control valve ( 21 ) of the second exhaust gas recirculation ( 12 ), so that no unfiltered exhaust gas ( 26 ) from the second exhaust gas recirculation ( 12 ) into the supply line ( 31 ) flows. This can be advantageous for a chemical and / or mechanical loading of the components in the region of the combustion chamber, in particular for an injector ( 4 ). Alternatively or additionally, however, an inflow of unfiltered, recirculated exhaust gas ( 26 ) be provided.

At the in 3 shown gas flow is the combustion chamber ( 2 ) is supplied with a charge air which consists almost exclusively or entirely of recirculated exhaust gas ( 25 . 26 ) and thus has a reduced oxygen content. That from the combustion chamber ( 2 ) led out exhaust gas is in the operating state with low fuel combustion, through the discharge line ( 32 ) and the one or more exhaust gas recirculations ( 11 . 12 ) to the feed side ( 29 ) returned.

It may be that a small amount of exhaust gas in the operating condition of the engine ( 1 ) with low fuel combustion from the discharge line ( 32 ) through an exhaust outlet ( 36 ) or discharges an exhaust into the open, while the fresh air supply is completely closed. In such a case, that in the system for conducting charge air and exhaust gas ( 28 ) decrease the amount of gas present. Alternatively, the controllable throttle ( 22 ) a small amount of fresh air on the feed side ( 29 ), which can lead to a constant oxygen content or to a small and controllable increase in the oxygen content in the charge air. In this case, by the emission of exhaust gas from the exhaust gas outlet ( 36 ) decrease in the amount of gas partially or completely compensated.

The system for conducting charge air and exhaust gas ( 28 ) preferably has a control device ( 24 ) for the controllable throttle ( 22 ) on. The control device ( 24 ) is designed to control the controllable throttle ( 22 ) to cause it to open or close. The control device ( 24 ) can, for example, with a motor controller (not shown) and receive from these default values, from which the control device ( 24 ) a desired flow rate of fresh air ( 27 ) can calculate.

The control device ( 24 ), the controllable throttle ( 22 ) cause it to open or close due to an energization. The control device ( 24 ) may in particular be designed to provide a flow rate of fresh air ( 27 ) at the controllable throttle ( 22 ) by controlling the opening degree of the controllable throttle ( 22 ) is set to a predetermined value. Such an opening degree can be predetermined, for example, via a flap angle in a region between a completely open position and a completely closed position. The control device ( 24 ) may alternatively be integrated in a motor control.

In 4 are diagrams 4a, 4b, 4c and 4d, the characteristic values in an exemplary operation of an internal combustion engine ( 1 ). For easier visualization, it is assumed that this is an internal combustion engine ( 1 ) on a vehicle.

The uppermost diagram 4a shows the course of a fuel quantity (QFIN) injected per piston stroke over time (t). Graph 4b indicates an accumulated value of NOx emission (Acc NOx) over time (t), and Graph 4c shows instantaneous NOx emission (NOx) over time (t). The lowermost diagram 4d indicates a velocity profile (v) of the vehicle over time (t).

The four diagrams 4a, 4b, 4c and 4d relate to the same physical sequence. In the diagrams, the progression of the respective quantities in a system according to the invention are indicated by a solid line ( 50 ) and with a dashed line the course of the respective variables in a comparison system ( 51 ).

The exemplary operation of the internal combustion engine shown is divided into four sections A, B, C, D on the time axis. The sections A and C each indicate an operating state of the internal combustion engine ( 1 ), in which this is in a no-load operation and the amount of fuel burned per piston stroke (QFIN) is very low. In such a condition, the speed of the vehicle decreases as shown in diagram 4d.

Sections B and D indicate an operating condition of the internal combustion engine ( 1 ), in which the engine ( 1 ) in loaded operation and a comparatively large amount of fuel (QFIN) is burned per piston stroke. According to diagram 4d, in such an operating state B, D, for example, the speed (v) of the vehicle is kept constant. Alternatively, an acceleration of the vehicle could also be present in such an operating state.

In application of the method according to the invention for operating a system for conducting charge air and exhaust gas ( 28 ) on an internal combustion engine ( 1 ) is a fresh air supply ( 9 ) by actuating the controllable throttle ( 22 ) in an operating condition of the engine ( 1 ) is reduced or closed, in which one per piston stroke in a combustion chamber ( 2 ) burned fuel quantity (QFIN) becomes very low or zero. Accordingly, in sections A and C in the diagrams in 4 the fresh air supply ( 9 ) by actuating the controllable throttle ( 22 ) closed. As a result, an oxygen content in the charge air during the continuation of the operating state A, C is kept low with low fuel combustion.

When changing the operating state, ie at an operating state of the internal combustion engine ( 1 ), in which one per piston stroke in a combustion chamber ( 2 ) the amount of fuel burned (QFIN) is increased again from a very low value or from zero, the fresh air supply ( 9 ) by actuating the controllable throttle ( 22 ) opened or raised again. This is in diagrams of 4 in sections B and D of the case.

As can be seen from the diagram 4c, the course of the NOx-emission (NOx) in a comparison system ( 51 ) of the known type after a change of the operating state (A → B, C → D) a pronounced elevation (peak). On the other hand, the NOx emission (NOx) remains in the system according to the invention ( 50 ) after changing the operating state (A → B, C → D) to a much lower value. The hatched areas in the diagram 4c illustrate the differences between the ejected amounts of NOx in the system according to the invention ( 50 ) and in the comparison system ( 51 ). The hatched area ( 52 ) corresponds to that after a change of the operating state (C → D) by the system according to the invention ( 50 ) saved amount of NOx.

From the graph 4b it can be seen that the accumulated amount of NOx (Acc. NOx) in the system according to the invention ( 50 ) compared to the accumulated amount of NOx (Acc. NOx) of the comparison system ( 51 ) is significantly reduced. The more frequently a change of operating state (A → B, C → D) takes place from a low fuel combustion state to a higher fuel combustion state, the greater the NO x emission reduction can be. The discharge of particulates and other pollutants may also behave in the manner shown in Diagram 4c for NOx emissions.

The invention is not limited to the embodiment shown and described. The features of the invention may be combined, interchanged or omitted in any manner. The system for conducting charge air and exhaust gas ( 28 ) on an internal combustion engine ( 1 ) can be applied to any type of internal combustion engine, such as gasoline engines, diesel engines or gas engines. The use of the internal combustion engine ( 1 ) can be mobile, for example in land or water vehicles, or stationary, for example, to feed the grid or to drive a machine.

The one in the combustion chamber ( 2 ) fuel to be combusted can be added in any way, for example, by direct injection into the combustion chamber, by Vorkammeinspritzung or by a carburetor. The system ( 28 ) can only be used via one or more exhaust gas recirculation systems ( 11 . 12 ) feature. Each of the exhaust gas recirculations may include one or more recirculation lines ( 16 . 17 ) exhibit.

The during an operating condition of the engine ( 1 ) with low fuel combustion cycle for charge air and exhaust gas in the system ( 28 ) can only via a first exhaust gas recirculation ( 11 ), only via a second exhaust gas recirculation ( 12 ) or via multiple exhaust gas recirculations ( 11 . 12 ) respectively. The choice of exhaust gas recirculation ( 11 . 12 ) may depend on the type of fuel.

A particularly simple embodiment of the invention can be designed such that on an internal combustion engine ( 1 ) only one exhaust gas recirculation ( 11 ) and that the controllable throttle ( 22 ) still allows a supply of a small amount of fresh air in a closed state. In such an embodiment, it may be possible for the controllable throttle ( 22 ) is displaceable only in an open or closed state. Such a designed controllable throttle ( 22 ) can be designed to be particularly simple and inexpensive, with a particularly low tax expense arises. LIST OF REFERENCE NUMBERS 1 internal combustion engine Internal combustion engine 2 combustion chamber Combustion chamber 3 . 3 ' Valve Valve 4 injector Injector 5 compressor Compressor 6 turbine turbine 7 Radiator, intercooler Cooler, Intercooler 8th particulate Filter Particulate filter 9 Fresh air Fresh air influx 10 exhaust removal Exhaust gas efflux 11 Exhaust gas recirculation (EGR) Exhaust gas recirculation (EGR) 12 Exhaust gas recirculation (EGR) Exhaust gas recirculation (EGR) 13 bypass bypass 14 cooler Cooler 15 cooler Cooler 16 Return line Recirculation duct 17 Return line Recirculation duct 18 Inflow of exhaust gas Influx of exhaust gas 19 Inflow of exhaust gas Influx of exhaust gas 20 control valve Control Valve 21 control valve Control Valve 22 Controllable throttle / shutter Controllable Restrictor / closing device 23 piston Piston 24 Control Device / Electronic Control Unit (ECU) Control device / electronic control unit (ECU) 25 Returned exhaust gas, filtered and / or at low pressure Recirculated exhaust gas, filtered and / or at low pressure 26 Returned exhaust gas, unfiltered and / or at high pressure Recirculated exhaust gas, unfiltered and / or at high pressure 27 fresh air Fresh air 28 System for conducting charge air and exhaust gas System for intake of air and exhaust gas 29 Feed side / the intake tract Supply side / intake section 30 Discharge side / exhaust tract Discharge side / exhaust section 31 supply line Supply duct 32 discharge line Discharge duct 33 engine intake Engine inlet 34 Engine exhaust Engine outlet 35 Fresh air inlet Fresh air inlet 36 Exhaust / Exhaust Exhaust gas outlet / exhaust 50 Inventive system System according to the invention 51 comparison system System of comparison 52 Saved NOx amount Saved NOx amount QFIN Amount of infection per piston stroke Quantity of fuel injected per piston stroke Acc. NOx Accumulated value of NOx emissions Accumulated value of NOx emission NOx NOx emissions NOx emission v speed speed t Time Time

Claims (16)

System for conducting charge air and exhaust gas on an internal combustion engine, which with respect to a combustion chamber ( 2 ) of the motor ( 1 ) a feed page ( 29 ) for the supply of charge air with a supply line ( 31 ) and a rejection page ( 30 ) for the removal of exhaust gas with a discharge line ( 32 ), wherein the system for conducting charge air and exhaust gas ( 28 ) at least one first exhaust gas recirculation ( 11 ) with a return line ( 16 ), by the exhaust gas from the discharge side ( 30 ) to the feed side ( 31 ) is traceable and wherein a return line ( 16 ) in an area behind a fresh air inlet ( 35 ) with the formation of an inflow of exhaust gas ( 18 ) with the supply line ( 31 ) and wherein the return line ( 16 ) with the discharge line ( 32 ) in an area behind a turbine ( 6 ) and wherein the system for conducting charge air and exhaust gas ( 28 ) a second exhaust gas recirculation ( 12 ) with a return line ( 17 ), and wherein the first exhaust gas recirculation ( 11 ) for returning low-pressure exhaust gas ( 25 ) and the second exhaust gas recirculation ( 12 ) for recirculating high-pressure exhaust gas ( 26 ) are formed, characterized in that in the supply line ( 31 ) between the fresh air intake ( 35 ) and the inflow of low pressure exhaust gas ( 18 ) a controllable throttle ( 22 ) for opening or closing the fresh air supply ( 9 ) and that the controllable throttle ( 22 ) is adapted to the fresh air supply ( 9 ) in a state of the engine ( 1 ), in which one per piston stroke in a combustion chamber ( 2 ) burned amount of fuel (QFIN) is very low or equal to zero. System for conducting charge air and exhaust gas according to claim 1, characterized in that the controllable throttle ( 22 ) is adapted to control the flow rate through the air inlet ( 35 ) to regulate incoming fresh air. System for conducting charge air and exhaust gas according to one of claims 1 or 2, characterized in that the system for conducting charge air and exhaust gas ( 28 ) on the feed side ( 29 ) a compressor ( 5 ) and / or on the discharge side ( 30 ) a turbine ( 6 ) having. System for conducting charge air and exhaust gas according to one of the preceding claims, characterized in that the system for conducting charge air and exhaust gas ( 28 ) on the feed side ( 29 ) an intercooler ( 7 ) having. System for conducting charge air and exhaust gas according to one of the preceding claims, characterized in that the system for conducting charge air and exhaust gas ( 28 ) on the discharge side ( 30 ) a particle filter ( 8th ) having. System for conducting charge air and exhaust gas according to claim 1, characterized in that the first exhaust gas recirculation ( 11 ) for recycling filtered exhaust gas ( 25 ) and the second exhaust gas recirculation ( 12 ) for returning unfiltered exhaust gas ( 26 ) are formed. System for conducting charge air and exhaust gas according to one of the preceding claims, characterized in that the system for conducting charge air and exhaust gas ( 28 ) a control device ( 24 ), which is adapted to the controllable throttle ( 22 ) to cause it to open or close. System for conducting charge air and exhaust gas according to one of the preceding claims, characterized in that a control device ( 24 ) for the controllable throttle ( 22 ) is connected to and / or integrated in a motor control. Internal combustion engine with a system for conducting charge air and exhaust gas, characterized in that the system for conducting charge air and exhaust gas ( 28 ) is designed according to one of claims 1 to 8. Internal combustion engine according to claim 9, characterized in that the internal combustion engine ( 1 ) is a diesel engine. Internal combustion engine according to one of claims 9 or 10, characterized in that the internal combustion engine ( 1 ) an injector ( 4 ) for injecting fuel into a combustion chamber ( 2 ) of the internal combustion engine ( 1 ) is trained. Internal combustion engine according to one of claims 9, 10 or 11, characterized in that the internal combustion engine ( 1 ) has a common rail system. Method for operating a system for conducting charge air and exhaust gas to an internal combustion engine, characterized in that the system for conducting charge air and exhaust gas ( 28 ) is designed according to one of claims 1 to 8 and that in an operating condition of the engine ( 1 ), in which one per piston stroke in a combustion chamber ( 2 ) burned fuel quantity (QFIN) becomes very low or zero, a fresh air supply ( 9 ) by actuating the controllable throttle ( 22 ) is closed. A method according to claim 13, characterized in that a flow rate of recirculated exhaust gas ( 25 . 26 ) is adjusted such that between discharge side ( 30 ) and feed side ( 29 ) via an exhaust gas recirculation ( 11 . 12 ) forms a circuit, wherein in the circuit of an engine outlet ( 34 ) exhausted gas to an engine intake ( 33 ), with no or only a very small amount of fresh air ( 27 ) is supplied. Method according to one of claims 13 or 14, characterized in that the circuit only via an exhaust gas recirculation ( 11 ) is formed, in which filtered and / or low-pressure exhaust gas ( 25 ) is returned. Method according to one of claims 13, 14 or 15, characterized in that in an operating state of the engine ( 1 ), in which one per piston stroke in a combustion chamber ( 2 ) burned Fuel quantity (QFIN) is increased again from a very low value or from zero, a fresh air supply ( 9 ) by actuating the controllable throttle ( 22 ) is opened or raised.

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