DE102016007208B4 - Method and system for controlling exhaust gases resulting from combustion - Google Patents

Abstract

A method for controlling exhaust gases resulting from combustion in an internal combustion engine (101), the internal combustion engine (101) having at least one combustion chamber (i1-i6) and an intake side (402) for taking in air for use in the combustion, wherein the internal combustion engine (101) is further configured to expel exhaust gases resulting from the combustion, the method comprising: - when the internal combustion engine (101) is performing at least a first work, providing an air flow from the intake side (402) for mixing with Exhaust gases resulting from the combustion, the air flow bypassing the at least one combustion chamber (i1-i6), and if the internal combustion engine (101) performs a second work that is less than the first work, recirculation of at least part of the exhaust gases resulting from the combustion to the suction side (402), the method being characterized by: - providing the air flow to the misc hen with the exhaust gases only when an internal combustion engine speed is lower than a first internal combustion engine speed, or / and providing the air flow for mixing with the exhaust gases only when the altitude of a vehicle (100) exceeds a first altitude, the at least one combustion chamber (i1 -i6) is a combustion chamber of an internal combustion engine (101) in the vehicle (100).

Description

Field of invention

The present invention relates to combustion processes and, more particularly, to a method and system for controlling an exhaust gas flow. The present invention also relates to a vehicle and a computer program and a computer program product which implement the method according to the invention.

General state of the art

With respect to vehicles in general, and at least in part, heavy duty vehicles, such as trucks, buses, and the like, there is ongoing research and development into increasing fuel efficiency and reducing exhaust emissions.

Often times, at least in part, this is due to growing government concerns about pollution and air quality, e.g. B. in urban areas, which have also led to the application of different emission standards and regulations in many areas of responsibility.

These emission standards often consist of specifications that define acceptable limits for exhaust emissions from vehicles equipped with internal combustion engines. The exhaust levels of e.g. For example, nitrogen oxides (NO _x ), hydrocarbons (HC), carbon monoxide (CO) and particulates are regulated in these standards for most types of vehicles.

The undesired emission of substances can be reduced by lowering fuel consumption and / or by using exhaust gas aftertreatment (cleaning) of the exhaust gases resulting from the combustion process.

For example, exhaust gases from the internal combustion engine can be treated through the use of a catalytic process. There are different types of catalytic converters, and different types can be used for different types of fuel and / or for treating different types of substances occurring in the exhaust gas stream.

A common type of catalytic converter, which is used in particular to reduce nitrogen oxides, NOx, is, for example, SCR catalytic converters (SCR = “selective catalytic reduction”).

There are other types of catalysts that are commonly used, particularly in the reduction of exhaust emissions resulting from combustion in commercial vehicles / heavy goods vehicles. Such catalysts include, for. B. Oxidation catalysts. Catalytic converters that are generally used for exhaust gas aftertreatment of an exhaust gas stream have in common that at least a minimum temperature must be maintained in the catalytic converter in order to ensure that the desired reactions occur. Furthermore, the catalysts can also be temperature-sensitive to the extent that excessively high temperatures can be harmful.

Possibilities for controlling air-fuel ratios of an exhaust gas as a function of a load on the engine are disclosed in the laid-open specification DE 10 2013 209 379 A1 disclosed. To cool the exhaust gas flow from the internal combustion engine, for example, compressed air can be fed to the exhaust gas flow while bypassing the internal combustion engine.

Summary of the invention

It is an object of the present invention to provide a method and system that control exhaust gases resulting from combustion in a combustion chamber. For example, the exhaust gases can be controlled based on a temperature condition of the exhaust gases. In this way, a temperature condition of one or more exhaust aftertreatment components exposed to the exhaust gas flow can also be controlled. This object is achieved by a method according to claim 1.

• - wenn der Verbrennungsmotor mindestens eine erste Arbeit leistet, Bereitstellen einer Luftströmung von der Ansaugseite zum Mischen mit Abgasen, die aus der Verbrennung resultieren, wobei die Luftströmung den mindestens einen Brennraum umgeht, und
• - wenn der Verbrennungsmotor eine zweite Arbeit leistet, die geringer als die erste Arbeit ist, Rückführen von mindestens einem Teil der Abgase, die aus der Verbrennung resultieren, zu der Ansaugseite.

According to the present invention, a method for controlling exhaust gases resulting from combustion in an internal combustion engine is provided, the internal combustion engine having at least one combustion chamber and an intake side for taking up air for use in the combustion, the internal combustion engine further being configured to do so To emit exhaust gases resulting from combustion. The procedure includes the following:

• if the internal combustion engine is performing at least a first work, providing an air flow from the intake side for mixing with exhaust gases resulting from the combustion, the air flow bypassing the at least one combustion chamber, and
• - when the internal combustion engine performs a second work that is less than the first work, recirculating at least a part of the exhaust gases resulting from the combustion to the intake side.

With respect to exhaust gases resulting from combustion, there are several ways to treat these exhaust gases in order to reduce harmful emissions into the environment of the vehicle. For example, it is common, at least in relation to heavy goods vehicles / utility vehicles, for nitrogen oxides NO _{x to be} reduced. Nitrogen oxides NO _x are formed during a combustion process for various reasons. The main reason for the generation of NO _x is, at least in relation to a combustion according to e.g. B. the diesel or Otto principle, in the thermal generation of NO _x , nitrogen in the air that is fed to the combustion, reacts spontaneously with oxygen at the high temperatures and pressures that occur in the combustion chamber.

The thermal generation of nitrogen oxides NO _x depends heavily on the temperature of the combustion, with higher temperatures leading to higher amounts of nitrogen oxides NO _x .

The amount of nitrogen oxides NO _x in the exhaust gas flow can be reduced before the exhaust gas flow is released into the surroundings of the vehicle, for example using an SCR catalyst (SCR = selective catalytic reduction). Such a reduction is not always sufficient and it is also possible to reduce the nitrogen oxides by recirculating part of the exhaust gases. Recirculated exhaust gases act as an inert gas during combustion and thus essentially do not react with the combustion gas (e.g. air) or the fuel that is present in the combustion chamber. The exhaust gas recirculation (commonly referred to as EGR) thereby lowers the maximum temperature that occurs during a temperature and consequently also the amount of nitrogen oxides NO _x that is generated during combustion.

With respect to EGR recirculation, the exhaust gas stream generated during combustion is usually relatively hot and since the formation of nitrogen oxides is dependent on the temperature encountered during combustion, recirculated exhaust gases are cooled before being returned to a combustion chamber will.

The cooling enables the use of higher EGR ratios, while at the same time the gas temperature on the intake side of the combustion chambers is lowered, which contributes to a lower maximum temperature and thereby a reduction in the nitrogen oxides generated.

However, there are exhaust gas aftertreatment systems that can satisfactorily remove nitrogen oxides using e.g. B. an efficient SCR catalytic converter without EGR recirculation is required. The present invention particularly relates to systems of this type. B. means for exhaust gas recirculation or other suitable means for achieving gas flows according to the invention are used, but in a manner which differs from the prior art.

In particular, the present invention relates to situations that may arise when certain vehicle operation and environmental conditions prevail. This is achieved by a method (and a system) by means of which an air flow from the intake side of the internal combustion engine is arranged to mix with exhaust gases resulting from the combustion when the internal combustion engine is doing at least some initial work.

Furthermore, at least a part of the exhaust gases resulting from the combustion is returned to the intake side when the internal combustion engine performs a second work that is less than the first work.

According to the invention, air from the intake side of the internal combustion engine is set up to bypass the combustion chambers for mixing with the exhaust gases when the work of the internal combustion engine exceeds a certain initial work, e.g. B. when hot exhaust gases are expected. In this way, hot exhaust gases can be cooled in situations in which hot exhaust gases can damage temperature-sensitive components through which the exhaust gases flow before they are released into the surroundings of the vehicle. Such situations can occur in particular at high altitudes and / or when the internal combustion engine load and thus the work produced are high at lower internal combustion engine speeds. Lower internal combustion engine speeds generally lead to lower volumes of air being transported through the combustion chambers of the internal combustion engine, as a result of which less cooling is provided. According to one embodiment, the diversion of air is only carried out if the altitude of the vehicle exceeds a first altitude. Since the air density is lower at higher altitudes, the mass flow of air through the combustion chambers is reduced at higher altitudes. This in turn leads to higher exhaust gas temperatures in relation to a similar operation at lower altitudes.

The internal combustion engine can include a plurality of combustion chambers that can be divided into groups or rows, and the air flow can be arranged to be mixed with exhaust gases from a subset of the plurality of groups of combustion chambers. When the combustion chambers, e.g. B. cylinders, for example in two or more groups n are subdivided, the air flow can be set up to deal with exhaust gases of at most n-1 groups, such as e.g. B. only one group / row out of the two or more groups to be mixed. The combustion chambers can for example be divided into two groups, the air flow to one of the groups, thereby z. B. half of the combustion chambers can be provided. After this mixing, exhaust gases from all of the combustion chambers can be mixed to form a combined exhaust gas stream that is configured to flow through at least one component for treating the exhaust gas stream.

As mentioned, the inventive method relates not only to adding an air flow to the exhaust gas stream, but also to recirculating exhaust gases to the air intake side of the engine when the internal combustion engine is doing a job equal to or less than the second job. The recirculation of uncooled exhaust gases reduces the intake of colder air and in this way the resulting temperature of the exhaust gases reaching exhaust aftertreatment components can be increased in situations in which the exhaust gases may otherwise cool exhaust aftertreatment components to an extent that can no longer function properly can be ensured. The recirculation of uncooled exhaust gases also reduces flow through the exhaust aftertreatment components, which is beneficial when the exhaust gases are not hot enough to provide proper heating of exhaust aftertreatment components. According to one embodiment, warm exhaust gases are recirculated when an average work performed by the internal combustion engine is at most the second work for a first period of time.

According to one embodiment, warm (uncooled) exhaust gases are recirculated when an internal combustion engine is rotating, but when no combustion takes place in the at least one combustion chamber.

• 1A stellt einen Antriebsstrang eines beispielhaften Fahrzeugs dar, in dem die vorliegende Erfindung vorteilhaft genutzt werden kann;
• 1B stellt ein Beispiel einer Steuereinheit in einem Fahrzeugsteuersystem dar;
• 2 stellt ein Beispiel von Abgasnachbehandlungskomponenten zur Behandlung von Abgasen, die aus einer Verbrennung resultieren, dar.
• 3 stellt ein beispielhaftes Verfahren gemäß einer Ausführungsform der vorliegenden Erfindung dar.
• 4A stellt ein beispielhaftes System gemäß einer Ausführungsform der vorliegenden Erfindung dar.
• 4B stellt ein beispielhaftes System gemäß einer anderen Ausführungsform der vorliegenden Erfindung dar.
• 5 stellt eine erfindungsgemäße Umleitung von Luft dar.
• 6 stellt eine erfindungsgemäße Abgasrückführung dar.

Further characteristics of the present invention and advantages thereof are given in the detailed description of exemplary embodiments which are listed below and in the attached drawings. Brief description of the drawings

• 1A Figure 13 illustrates a powertrain of an exemplary vehicle in which the present invention may be used to advantage;
• 1B Fig. 10 illustrates an example of a control unit in a vehicle control system;
• 2 Figure 3 illustrates an example of exhaust aftertreatment components for treating exhaust gases resulting from combustion.
• 3 Figure 10 illustrates an exemplary method in accordance with an embodiment of the present invention.
• 4A FIG. 10 depicts an exemplary system in accordance with an embodiment of the present invention.
• 4B FIG. 10 depicts an exemplary system in accordance with another embodiment of the present invention.
• 5 represents a diversion of air according to the invention.
• 6th represents an exhaust gas recirculation according to the invention.

Detailed description of exemplary embodiments

In the following detailed description of the present invention, an example of a vehicle is presented. However, the invention can also be used in other types of means of transport, such as aircraft and watercraft. The invention can also be used in fixed installations.

1A Figure 11 schematically shows a powertrain of an exemplary vehicle 100 . The drive train includes an energy source, in the present example an internal combustion engine 101 , which is carried out in a conventional manner by means of an output shaft of the internal combustion engine 101 , usually by means of a flywheel 102 with a gear 103 by means of a coupling 106 connected is. An output shaft 107 from the gearbox 103 drives drive wheels 113 , 114 by means of an axle drive 108 , such as a common differential gear, and drive axles 104 , 105 that come with the final drive 108 connected.

The internal combustion engine 101 is controlled by the vehicle control system by means of a control unit 115 controlled. The coupling 106 and the transmission 103 are also controlled by the vehicle control system using a control unit 116 controlled.

1A discloses a drive train of a specific type, but the invention is applicable to any type of drive train and also e.g. B. applicable in hybrid vehicles. The disclosed vehicle further comprises an exhaust gas aftertreatment unit 130 for exhaust gas aftertreatment (cleaning) of exhaust gases resulting from combustion in the internal combustion engine 101 result. The functions of the exhaust aftertreatment unit 130 are using a control unit 131 controlled. The exhaust aftertreatment unit 130 can be of various types and designs. An example of an exhaust aftertreatment unit 130 in which the present invention may be used is shown in 2 schematic shown. The exhaust gas flow 201 meets the components of the exhaust aftertreatment unit when it hits 130 first on a diesel oxidation catalytic converter (DOC) 202 .

The oxidation catalyst DOC 202 has different functions and is used, among other things, in exhaust gas aftertreatment to oxidize residual hydrocarbons and carbon monoxide in the exhaust gas flow to carbon dioxide and water. The oxidation of hydrocarbons (i.e. oxidation of fuel) also generates heat that can be used to raise the temperature of a particulate filter DPF 203 during the oxidation of soot, the so-called regeneration, of the particulate filter DPF 203 to increase. Oxidation can also generally be used to ensure that exhaust aftertreatment components are downstream of the oxidation catalyst 202 maintain a desired minimum temperature.

The oxidation catalyst 202 can also oxidize nitrogen monoxide (NO), which occurs in the exhaust gas flow, to nitrogen dioxide (NO ₂ ). This nitrogen dioxide is used, for example, in a NO ₂ -based regeneration of the diesel particulate filter DPF 203 is used, but the efficiency of the reduction in SCR catalytic converters (see below) also depends on the ratio between NO and NO ₂ in the exhaust gas flow and benefits from the NO ₂ conversion in the DOC oxidation catalytic converter 202 . Other reactions can also take place in the oxidation catalyst DOC 202 appear. As mentioned, a diesel particulate filter is DPF 203 located downstream of the oxidation catalyst and basically has the task of collecting particulates in the exhaust gas stream that, when the DPF 203 is filled to a certain suitable extent, can be processed by regeneration into less harmful compositions, as is known per se.

The disclosed exhaust aftertreatment unit 130 also includes an SCR catalyst (SCR = "selective catalytic reduction", selective catalytic reduction) 204, the downstream of the DPF 203 is arranged. SCR catalysts generally reduce z. B. nitrogen oxides NO _x in the exhaust gas stream through the use of an additive in a manner known per se.

The exhaust aftertreatment unit 130 finally includes an ammonia slip catalytic converter ASC ("ammonia slip catalytic converter") 205, the downstream of the SCR 204 is arranged. The ASC oxidizes excess ammonia that is in the exhaust gases after passing through the SCR 204 can remain. The ASC 205 can also use the SCR 204 support in a further NO _x reduction.

The components DOC 202 , DPF 203 , SCR catalytic converter 204 and ASC 205 can be in a single unit 130 be integrated. Alternatively, the components can be arranged in any other suitable manner and one or more of the components can for example consist of separate units. 2 further discloses temperature sensors 210-212 , the z. B. can be used in the temperature control of the components. In accordance with the invention, such temperature sensors may or may not be used and the temperature sensor device is exemplary only and any suitable sensor or number of sensors at any suitable location or locations can be used or no sensor at all can be used.

The operation of components of the in 2 disclosed type and perhaps in particular of the SCR catalytic converter 204 depends strongly on the prevailing temperature of the component. If the temperature of the component is too low, desired reactions may not take place and, conversely, if the temperature is too high, components may instead be damaged. For example, if the oxidation catalyst temperature is too low, the oxidation catalyst will not be able to remove residual hydrocarbons in the exhaust gas stream 201 to oxidize. _{The NO x} reduction of the SCR catalytic converter is analogous to this 204 does not take place to a desired extent when the temperature of the SCR catalyst 204 is too low.

The temperature of components of the exhaust aftertreatment unit 130 depends heavily on the temperature of the exhaust gas flow 201 away. Components of this type are generally relatively well insulated and are affected by the ambient temperature, e.g. B. the temperature in the vehicle environment, to a much lesser extent when the vehicle is in operation.

The present invention provides a method that affects the exhaust gas temperature of the exhaust gas entering exhaust aftertreatment components, and this method controls, at least in some situations, the exhaust gases by affecting the exhaust gas temperature in a manner that is beneficial to the temperature of the exhaust aftertreatment components. For example, the present invention can be used to manipulate exhaust gas temperatures when driving conditions are such that the resulting exhaust gases (the resulting exhaust gas temperature) can have an adverse effect on the operation and / or life of the exhaust aftertreatment components.

An exemplary method of the present invention is shown in FIG 3 shown. The method can, at least in part, e.g. B. in the engine control unit 115 for controlling the operation of the internal combustion engine 101 implemented. The functions of a vehicle are generally controlled by a number of control units and control systems in vehicles of the type disclosed generally comprise a communication bus system consisting of one or more communication buses for connecting a number of electronic control units (ECU) or Controllers with various components on board the vehicle. Such a control system may comprise a large number of control units, and control of a specific function may be shared between two or more of them.

For simplicity shows 1A control units only 115-116 , 131 , Vehicles 100 however, of the type shown are often provided with significantly more control units, as a person skilled in the art will appreciate. The control units 115-116 , 131 are set up to communicate with each other and with various components by means of the communication bus system and other wiring, which is partly through connection lines in 1A are indicated to communicate.

The present invention can be incorporated into any suitable control unit in the vehicle 100 and therefore not necessarily in the control unit 115 implemented. The control that affects the resulting exhaust gas temperature according to the present invention will usually depend on signals received from other control units and / or vehicle components, and it is generally the case that control units of the type disclosed are normally adapted to receive sensor signals from various Parts of the vehicle 100 to recieve. The control unit 115 can, for example, signals z. B. from the control unit 131 and receive various sensors related to the control of the internal combustion engine. In addition, the control unit 115 be configured to receive sensor signals from one or more valves used in implementing the present invention in accordance with the following. Control units of the type shown are also usually adapted to send control signals to various parts and components of the vehicle, e.g. To valves and engine brake etc., according to the following, and / or to control units that control functions of the vehicle used by the present invention. All of this is known to those skilled in the art.

This type of control is often achieved through programmed instructions. The programmed instructions usually consist of a computer program which, when executed in a computer or a control unit, causes the computer / control unit to exercise the desired control, such as method steps according to the present invention. The computer program usually forms part of a computer program product, the computer program product being a suitable storage medium 121 (please refer 1B) comprises, wherein the computer program 126 on the storage medium 121 is stored. The computer program can be stored on the storage medium in a non-volatile manner. The digital storage medium 121 can for example consist of any of the group comprising: a ROM (“read-only memory”), a PROM (“programmable read-only memory”), an EPROM (“erasable PROM”) PROM), a flash memory, an EEPROM (“electrically erasable PROM”, electrically erasable PROM), a hard disk unit, etc., and can be arranged in or in connection with the control unit, whereupon the computer program is executed by the control unit. The behavior of the vehicle in a specific situation can thus be adapted by modifying the instructions of the computer program.

An exemplary control unit (the control unit 115 ) is schematically in 1B shown, the control unit being a processing unit 120 may comprise, for example, any suitable type of processor or microcomputer, such as a digital signal processing circuit (digital signal processor, DSP) or a circuit with a predetermined specific function (application specific integrated circuit, ASIC), can exist. The processing unit 120 is with a storage unit 121 connected to that of the processing unit 120 z. B. the stored program code 126 and / or provides the stored data that the processing unit 120 required in order to be able to perform calculations. The processing unit 120 is also set up in such a way that it stores partial or final results of calculations in the storage unit 121 saves.

Furthermore is the control unit 115 with fixtures 122 , 123 , 124 , 125 equipped for receiving and transmitting input and output signals. These input and output signals can include waveforms, pulses, or other attributes that the devices 122 , 125 for receiving input signals as information for processing by the processing unit 120 can capture. The devices 123 , 124 for transmitting output signals are set up so that they receive calculation results from the processing unit 120 into output signals for transfer to other parts of the vehicle control system and / or the component or components for which the signals are intended. Each one of the connections to the devices for receiving and transmitting respective input and output signals can consist of one or more of a cable; a data bus, such as a CAN bus (Controller Area Network Bus), a MOST bus (Media Oriented Systems Transport Bus) or any other bus configuration, or a wireless connection.

To the first exemplary method 300 , this in 3 is shown, returning, the method starts in step 301 where it is determined whether the exhaust gases are to be controlled according to the invention. The process remains in step 301 as long as this is not the case. The procedure continues with step 302 continues when it is determined that the exhaust gases are to be controlled in accordance with the present invention. The transition from step 301 to step 302 can for example be initiated according to various criteria. The control can be set up, for example, to be carried out at any time. Alternatively, the control according to the invention can be set up to be carried out, e.g. B. when conditions, e.g. With respect to internal vehicle operating conditions or conditions related to the surroundings of the vehicle, meet a certain criterion. Such conditions can relate, for example, to the current load on the internal combustion engine and thereby the amount of work produced, the vehicle speed, the ambient temperature, the altitude at which the vehicle is being driven, or any suitable combination of such criteria. Other suitable criteria for making the transition from step 301 to step 302 can also be applied. As explained further below, such a criterion can also include a determination of whether the internal combustion engine work is low or whether there is no fuel injection at all. It is also possible to use the time during which certain conditions have prevailed as a criterion.

In step 302 It is determined whether there is a risk that the current engine operation can damage exhaust aftertreatment components due to a high resulting exhaust gas temperature, and consequently air should be added to the exhaust gas flow. If this is the case, the procedure continues with step 303 away; otherwise the procedure continues with step 306 away. This is explained further below.

Internal combustion engines exist that can produce exhaust gases that are at such high temperatures that the hot exhaust gases can damage exhaust aftertreatment components and perhaps particularly SCR catalytic converters, which are often relatively temperature sensitive. The risk of this occurring can perhaps be highest at high altitudes, where the air is thinner, and especially in combination with low engine speeds while at the same time high torque is being delivered by the internal combustion engine.

When a vehicle is traveling at high altitudes, the same airflow will be drawn through the air filter; However, higher altitudes mean a lower density of the air and thus a lower volume flow and consequently less air that is fed to the combustion chambers. In these situations, the total air flow rate can consequently be significantly less than the air flow rate at lower altitudes and / or at higher engine speeds. The resulting exhaust gas temperature depends on the amount of fuel that is supplied to the combustion chambers and the amount of air in which the combustion is carried out. If less air is available for combustion, this will lead to higher exhaust gas temperatures. The lower amount of air flow means that a smaller amount of air flows through the engine, as a result of which a lower cooling effect and higher exhaust gas temperatures are provided.

The negative influence of higher altitudes is further increased if the internal combustion engine delivers high loads (high torques) at low engine speeds. This is because the lower engine speeds also reduce the total amount of air flowing through the engine per unit of time, thereby providing less cooling. If the internal combustion engine delivers a certain arbitrary torque at a certain internal combustion engine speed, this will lead to higher temperatures than if the same load / torque is delivered at a higher internal combustion engine speed, as in this case higher amounts of air flow through the engine and thereby provide additional cooling .

The general trend in engine development is toward downspeeding, the ability to provide high torque at low engine speeds for improved fuel efficiency. This further emphasizes low speed, high load operation. Problems of the above type, however, can result in situations where engines that would be very economical from a manufacturer's standpoint and / or fuel efficient from a customer standpoint, possibly due to the risk of generating too high exhaust gas temperatures at full load when operating at lower engine speeds cannot even be built.

At least the internal combustion engine may have been restricted with respect to high loads when operating at lower internal combustion engine speeds in order to prevent the risk of overheating of components exposed to the exhaust gas flow. As a result, the amount of fuel delivered to combustion must sometimes be reduced at at least some engine speed intervals in order to protect exhaust aftertreatment components.

The present invention provides a solution to problems of this type, among other things, and enables use of engine operation which otherwise might not be impossible without the risk of damaging components. In addition, the present invention also addresses problems in other driving conditions discussed below in relation to steps 306-309 from 3 is explained.

An exemplary system in accordance with the present invention is shown in FIG 4A disclosed. The figure shows an exemplary internal combustion engine 101 with six combustion chambers in the form of cylinders i1-i6. The internal combustion engine 11 may of course include any suitable number of cylinders / combustion chambers.

Each combustion chamber i1-i6 comprises an inlet (not shown) which e.g. B. is controlled by one or more valves and which can be set up to be controlled individually acting against the combustion chambers for the intake of air for use in the combustion. The motor 101 further comprises a suction line 402 , the z. B. consists of pipelines, pipes and / or hoses for taking up air for supply to the combustion chambers i1-i6. The air generally consists of air from the surroundings of the vehicle.

In accordance with the disclosed example, ambient air is removed from the vehicle / engine environment through an air filter 404 from an intake side 404A of the air filter 404 exposed to ambient air and drawn through the air filter 404 using a compressor 406 drawn. The compressor 406 is operated by a turbine 408 driven, the compressor 406 and the turbine 408 using a wave 410 are interconnected, thereby forming a conventional turbocharger. The compressed air is made by an intercooler 412 cooled in a manner known per se before they enter the suction line 402 and the combustion chambers i1-i6 of the internal combustion engine 101 is fed. Internal combustion engines of the type disclosed further generally include at least one injector per combustion chamber (not shown) that supplies fuel for combustion in a conventional manner.

The combustion chambers i1-i6 further comprise exhaust gas outlets which, for. B. also by means of valves against the combustion chambers i1-i6 can be controlled in a conventional manner, for releasing exhaust gases. According to the disclosed embodiment, exhaust gases emerging from cylinders i1-i3 share a common line 414 from exhaust outlets to a first inlet 408A the turbine 408 . Accordingly, exhaust gases emerging from cylinders i4-i6 share a common line 416 that came from the line 414 is separated, from exhaust outlets to a second inlet 408B the turbine 408 . The turbine 408 consequently includes separate exhaust gas inlets for receiving exhaust gas streams from the conduit 414 or. 416 , the z. B. form a conventional twin-flow turbine. The turbine 408 also forms a turbine with a fixed geometry and a boost pressure control valve 418 is with one or both of the lines 414 , 416 connected to the turbine bypass if required.

The exhaust gas flow is from the turbine 408 through a single common outlet 408C ejected and is by means of an engine brake 420 to the exhaust aftertreatment unit 130 for exhaust aftertreatment of exhaust gases according to the above before being released into the surroundings of the vehicle 100 is released.

According to the exemplary embodiment, the SCR catalytic converter itself is able to reduce nitrogen oxides to a desired extent, and thus no further reduction is required. As explained above, it is often necessary to recirculate exhaust gases actively cooled by the use of a cooler in order to meet specifications with regard to NO _x emissions. However, according to the example disclosed, an exhaust gas recirculation circuit is still provided, but is used in a completely different context from the prior art and in a manner contrary to the prior art. According to the invention there is no such recirculation of cooled exhaust gases. Instead, warm (uncooled) exhaust gases are recirculated in situations in which there is a desire to increase the exhaust gas temperature. The invention also provides a gas flow in both directions through the exhaust gas recirculation components, the flow direction being controlled as a function of the current operating conditions of the vehicle.

According to the example disclosed, the line is 416 with an EGR valve 422 with the help of a suitable line 426 in a manner known per se and further by means of a closable valve 424 , e.g. B. a divider valve that z. B. on a surface or in the immediate vicinity of the line 416 is arranged, connected so that the line 426 between the line 416 and the EGR valve 422 can essentially be separated from the exhaust system if the pipes 426 , 428 are not in use, thereby introducing minimal disturbance to the flow of exhaust gas. The EGR valve 422 is still with the suction line 402 of the internal combustion engine 101 through a line 428 tied together.

As mentioned, situations may exist in which the exhaust gas flow resulting from combustion in the combustion chambers reaches temperatures which, at least over time, can heat exhaust aftertreatment components to temperatures at which there is a risk of damage. Perhaps this is particularly true of the SCR catalytic converter 204 which is generally highly temperature sensitive to the possibility of suffering physical damage when exposed to high temperatures.

Proceed to the procedure of 3 can, as mentioned, in step 302 it can be determined whether there is a risk that a situation of this kind may arise, and if this is the case, the method continues with step 303 away. The determination can e.g. On the basis of signals from an altimeter or any other suitable means of determining vehicle altitude, e.g. B. a satellite navigation system.

According to the present example, the exhaust gases resulting from combustion are cooled by supplying air from the intake side of the internal combustion engine to the exhaust gases, thereby bypassing the combustion chambers. In step 303 thus becomes an appropriate control of the diversion of air from the suction pipe 402 to the exhaust gas discharge line 416 determined, whereby the combustion chambers i1-i6 are bypassed. This determination can be determined, for example, on the basis of the altitude of the vehicle, which can be determined by any suitable sensor, topographical data or the like. The determination in step 303 can also be set up as an alternative or in addition to this, e.g. B. based on the current engine load and / or the current vehicle speed, etc. The determination can also be e.g. Based on the time during which such conditions have prevailed.

The control of the diversion of air can e.g. B. from a determination of a bypass flow of the air and / or a suitable control / opening of the EGR valve 422 exist. The flow and / or opening of the EGR valve can for example be determined using a look-up table, e.g. B. Altitudes, loads, engine speeds, time periods and a suitable diversion setting and / or flow can be determined for different situations, the table z. B. can be determined empirically. Alternatively, a suitable algorithm can be used. According to one embodiment, signals from one or more temperature sensors, e.g. B. the temperature sensors 210-212 from 2 , can be used to control the bypass flow continuously or at intervals based on the resultant exhaust gas temperature so that a suitable temperature is achieved.

If a suitable control has been determined, the method continues with step 304 continue in which the controller by opening the valve 424 , which is closed in normal operation, is started and the EGR valve 422 is controlled to open to a certain extent in order to control the flow from the suction line as desired 402 to the exhaust pipe 416 to achieve. According to one embodiment that is described in 4B is shown schematically, the EGR valve 422 completely omitted and only one valve 424 is used. That is, the valve 424 can be arranged to control the air flow, e.g. B. by a suitable throttling. In its simplest form, from a fully open to a fully closed position and vice versa. The invention is described below with reference to the in 4A illustrated embodiment explained by the EGR valve 422 The effect achieved can, however, consistently be achieved through the valve instead 424 be achieved.

5 , the 4A is similar, represents the direction of air flow from the suction side 402 to the line 416 by arrows 502 , 504 , 506 With regard to the flow, this can be arranged to use e.g. B. a flow meter in the EGR circuit, a control using an appropriate setting of the EGR valve 422 however, it is generally sufficient. According to one embodiment, the EGR valve 422 fully opened in the control of the invention to allow the resultant flow to be whatever the resultant flow becomes, the actual flow thereby being dependent on prevailing pressures in the system. According to one embodiment, the EGR valve can be opened and closed alternately in order to achieve a suitable average flow over time. According to one embodiment, the control of the valve 424 and / or the EGR valve 422 performed on the basis of one or more temperatures, e.g. B. from any of the temperature sensors 210-212 be measured.

As a result, a conventional EGR circuit is used according to the invention, but in a manner opposite to the prior art, ie air is directed from the intake side to the exhaust side of the internal combustion engine when the load is high instead of the other way around. According to the in 4A The embodiment shown is air from the suction line 402 set up to bypass combustion chambers i1-i6 for mixing with exhaust gases from only one row (cylinder i4-i6) of cylinders. As the exhaust gas flows from the pipe 412 or. 416 but at the turbine outlet 408C are combined, the air diversion will have a cooling effect on the combined exhaust gas flow that reaches the exhaust gas aftertreatment components, and thus reduce a negative temperature influence of the current operating conditions of the internal combustion engine. According to one embodiment, air is from the suction line 402 set up to bypass combustion chambers i1-i6 for mixing with exhaust gases from any number of cylinders or all cylinders.

In order to ensure correct operation, the method described requires that the pressure in the intake line is higher than on the exhaust side in order to achieve a desired flow direction. However, this is generally the case with internal combustion engine operation, particularly with regard to internal combustion engines equipped with a turbocharger. However, the effect can also be achieved if the pressure relationship does not meet these criteria, e.g. B. by using a venturi. Such generation of a flow from a low-pressure side to a high-pressure side is well known per se and is consequently not described in detail herein. However, as mentioned, in general, pressure relationships are such that no venturi is required in the installation.

A control according to the invention furthermore achieves the result that a greater total flow passes through the turbine 408 will achieve. This in turn means that the speed of the turbine increases, with the further result that the compressor 406 the compression of intake air is further increased. This in turn means that a control according to the invention controls the pressure level in the intake line 402 does not necessarily lower, but rather maintains or increases the prevailing pressure level. Opening the EGR valve 422 will continue to cause a pressure increase on the exhaust side of the internal combustion engine, which in turn causes the internal combustion engine 101 forced to work a little harder due to the increased back pressure as exhaust gases are expelled from the cylinders, with a corresponding increase in fuel consumption as a result. As a result, the present invention provides a solution which, while causing a small increase in fuel consumption, results in the exhaust gases being cooled.

In step 305 it is checked whether a control according to the invention should be ended and the air diversion should be stopped. This may be the case, for example, when engine operating conditions have improved from an exhaust temperature standpoint. The procedure returns to step 304 back as long as this is not the case. Alternatively, the process can go to step 303 return for an adjustment of the bypass flow of air, e.g. B. when the conditions have changed. If it is determined that the air diversion is no longer required, the method may be configured to go to step 301 to return, waiting for a next opportunity when control according to the above is required. In this case the valve can 424 are closed to additional and undesired volumes for undesired exhaust gas expansion and thereby an associated loss of energy to drive the turbine upstream of the turbine 408 from the EGR circuit when this circuit is not in operation.

According to 5 As a result, the control carried out can be set up to be activated when required, e.g. B. in driving situations in which undesired exhaust gas temperatures occur. Since the present invention can cool the exhaust gases, the manufacture of engines which can be subjected to high loads at low engine speeds is facilitated, since problems with high exhaust gas temperatures can at least be alleviated.

The steps 303-305 and 5 refer to a situation where the resulting exhaust gases are too high for one or more components exposed to the exhaust gas stream. However, it is also possible that the situation is reversed. This is continued with reference to the steps 306-309 and 6th shown as an example. As mentioned above, exhaust aftertreatment components can be sensitive to high temperatures. However, the processes that take place in such components during operation of the vehicle generally require that the components maintain a minimum temperature in order to ensure correct operation. An SCR catalytic converter, for example, requires a minimum temperature to ensure that the reduction takes place to the desired extent. The oxidation catalytic converter must also maintain a certain temperature, otherwise there will be no or insufficient oxidation. As a result, if the temperature gets too low, desired reactions that occur in the exhaust aftertreatment components can be reduced to a level on which the vehicle z. B. Legislative requirements regarding emissions no longer met. The desired reaction can also stop completely.

As a result, it is also desirable to ensure that exhaust aftertreatment components maintain a desired minimum temperature. With regard to the temperature of the exhaust aftertreatment components, the temperature is almost completely controlled by the exhaust gas temperature / flow. Cooling exhaust gas aftertreatment components with ambient air has less of an impact, since the exhaust aftertreatment components are often relatively well insulated.

For example, when the internal combustion engine is exposed to low loads, it is not uncommon for the resulting exhaust gas temperatures to become so low that exhaust aftertreatment components are cooled down over time to such an extent that correct operation can no longer be ensured or maintained. Situations of this kind generally have to be taken into account and according to conventional solutions this is e.g. B. achieved by restricting the air that is fed to the combustion. This can be achieved, for example, by using an intake throttle indicated by 606 and dashed lines in 6th is shown. Use of such an intake throttle is not required according to the present invention.

If the amount of intake air is reduced through the use of an intake throttle, a pressure that is below the current atmospheric pressure is also generated in the intake manifold and thus also in the combustion chambers. This can cause engine lubricant to run past the cylinder piston and collect on the top of the piston. This, in turn, can coke the top region of the piston, ultimately causing cylinder failure. As a result, use of such technology is very undesirable. Another measure that can be taken in low-load situations is to reduce the intake air by opening the boost pressure control valve 418 reduce, reducing the speed of the turbine 408 and thus the compressor speed and thereby the intake air pressure are reduced.

The work done by the internal combustion engine can also be performed using e.g. B. the engine brake 420 in addition, the back pressure and thereby the load of the internal combustion engine 101 to increase, to be increased. The efficiency of the internal combustion engine can also be reduced, e.g. By using delayed ignition / fueling. These methods result in poor fuel efficiency.

However, an exhaust temperature that augments actions of this type is often insufficient, with the result that the resulting exhaust gases are still too cold to ensure proper heating of the exhaust aftertreatment components. If the work produced by the internal combustion engine is low, for example, there may no longer be any significant intake air pressure to be reduced, ie there is no longer any compression. If this is the case, the boost pressure control valve will open 418 essentially have no effect.

The above also applies to an even greater extent when the vehicle is coasting, particularly when it is coasting with the engine rotating and in gear with no fuel being supplied. During coasting, cold air is flooded through the engine and thereby also the exhaust aftertreatment components without being subjected to essentially any heating. This flow of cold air through the engine subjects the exhaust aftertreatment components to significant cooling. With regard to roll-out, the available measures to be taken to reduce the negative impact on the cooling exhaust gases are even more limited since there is generally no combustion. The intake air can be throttled, but can lead to cylinder failure again.

Often, at least in hilly terrain, downhill stretches of a road are of such a length that the exhaust gas aftertreatment components are cooled to such an extent that the resulting emissions will no longer meet legal requirements if the driving resistance and thereby the load on the internal combustion engine increase again after the downhill stretch of the road . The fulfillment of an exhaust emission target by the vehicle is often checked by on-board diagnostics, and if the vehicle control system determines that the exhaust gas aftertreatment is not working correctly, measures are taken to ensure correct operation of the exhaust aftertreatment again as quickly as possible. This can have the effect that the vehicle can be driven uphill with a considerable engine load due to the driving resistance imposed by the road gradient, however, e.g. B. the engine brake is still activated in order to further increase the internal combustion engine load in order to achieve the desired temperatures in the exhaust gas aftertreatment components more quickly.

According to the invention, negative effects that are caused by undesired cooling of exhaust gas aftertreatment components are avoided by recirculating uncooled (warm) Reduced exhaust gas. As was mentioned in step 301 determines whether the exhaust gas flow is to be controlled according to the invention, with the transition from step 301 to step 302 can be initiated according to the various criteria mentioned above, e.g. B. may include situations with little / no load and / or coasting situations. In this case, step 302 determines that there is no risk of current engine operation damaging exhaust aftertreatment components due to excessive heating, and thus the method proceeds to step 306 away.

In step 306 it is determined whether exhaust gases are coming from the exhaust pipe 416 to the suction line 402 should be recycled using the same EGR circuit as used above. This determination can be made, for example, in a manner similar to the above, and can be made on the basis of e.g. B. the current engine load and / or the current vehicle speed, the time during which various conditions have prevailed, etc. can be determined. If a return is to be carried out, the procedure continues with step 307 to determine appropriate control of the exhaust gas flow recirculation.

Control of the recirculation flow of exhaust gases can e.g. B. from a determination of a suitable control / opening of the EGR valve 422 exist. The flow and / or the opening of the EGR valve 422 can for example be determined using a look-up table in a manner similar to the above, this table e.g. B. can be determined empirically. It is also possible to use any suitable conventional EGR mechanism described in the art. Alternatively, a suitable algorithm can be used. According to one embodiment, the control consists of opening the valve 424 and the EGR valve 422 , while at the same time a suitable back pressure is established to ensure the return.

If in step 307 a suitable control has been determined, the method continues with step 308 continue in which the controller by opening the valve 424 is started and the EGR valve 422 is controlled to open to a certain extent to the desired control of the flow from the exhaust pipe 416 to the suction line 402 to achieve. This is done in 6th by arrows 602 , 604 disclosed. In order to ensure a flow in the desired direction, ie from the exhaust line to the intake line, the engine brake can for example be at least partially closed in order to increase the engine counter pressure, so that the pressure in the exhaust line 416 prevails, the pressure in the suction line 402 will exceed. The pressure difference generated must also take into account a possible pressure drop through the EGR circuit in order to ensure a correct flow direction through the EGR circuit. If the turbocharger is of a variable geometry turbine (VGT) type, the turbocharger can instead be used to increase the back pressure. It is also possible, e.g. B. also a Venturi nozzle in this control or z. B. to use an exhaust gas compressor. It is also possible, e.g. B. the passage from the exhaust pipe 416 to close the turbocharger, thereby discharging the exhaust gases to the intake manifold 402 to force. As one skilled in the art will appreciate, in principle any suitable means can be used as a throttling device for throttling the flow of exhaust gas, if necessary, e.g. B. to increase the back pressure of the engine to ensure a desired flow in a desired flow direction according to the above. The pressure difference can also be increased, for example, through the use of an intake throttle, such as the intake throttle 606 , although consideration should be given to possible resulting pressures below atmospheric pressure.

The EGR valve 422 can be set up, e.g. B. to be fully opened, and recirculation according to the invention can be controlled by a means according to the above. If the back pressure is controlled to a pressure in excess of the intake pressure, in principle all of the exhaust gas flow from the cylinders i4-i6 can be returned to the engine intake side. According to one embodiment, the EGR valve can be opened and closed alternately in order to achieve a suitable average exhaust gas recirculation over time.

As a result, the EGR circuit is also used for exhaust gas recirculation according to the invention, but not in the conventional sense in which actively cooled exhaust gases are recirculated during high engine loads, but instead warm exhaust gases are recirculated when the load is low or when there is no fuel injection at all. The recirculated exhaust gases generally have a higher temperature than the intake air and will therefore increase the temperature in the combustion chambers compared to a situation in which there is no exhaust gas recirculation. In general, an increase in the temperature of the gas fed to combustion by a first number of degrees will result in a substantially corresponding increase in the temperature of the resulting exhaust gases.

In general, recirculated exhaust gas is actively cooled before it reaches the intake side of the engine in order to minimize the increasing influence of the temperature in the combustion chamber and thereby to minimize the _{formation of NO x} during combustion. In contrast, according to the invention, it is desirable that the exhaust gases are as warm as possible in order to minimize the cooling effect during low / no load conditions. Recirculated exhaust gases are consequently not actively cooled according to the invention. Since, according to the disclosed example, half of the exhaust gases can be recirculated to the intake side of the internal combustion engine, the resulting exhaust gas flow is also reduced to half the flow that would otherwise go through the exhaust gas aftertreatment and is still at a higher temperature than it would otherwise Case would be. As a result, the present invention provides a solution that can substantially reduce the negative impact of cold exhaust gases on the operation of exhaust aftertreatment components.

According to the 4th , 6th As shown in the embodiment shown, exhaust gases from only one bank (cylinders i4-i6) of the cylinders are arranged to be returned to the suction side, and in this case half of the cylinders. The recirculation can, however, be set up to be carried out by any number of cylinders / combustion chambers, ie more or less than is exemplified above. This applies to internal combustion engines with any number of cylinders. It is also possible to have the return from a position downstream of the turbine 408 , e.g. B. upstream of the engine brake to perform.

In step 309 it is checked whether a return according to the invention should be ended. This may be the case, for example, when internal combustion engine operating conditions have changed and exhaust gases can be produced at a sufficient temperature without recirculation. The procedure returns to step 308 back as long as this is not the case. Alternatively, the process can go to step 307 in the event that control parameters are to be changed. If it is determined that the recirculation of exhaust gases is no longer required, the method may be adapted to go to step 301 to return, waiting for a next opportunity when control according to the above is required. Analogous to the above, the valve 424 are closed in order to influence the exhaust gas flow in normal operation as little as possible, in particular to provide additional and undesired volumes for exhaust gas expansion upstream of the turbine 408 according to the above.

According to 5 As a result, the control carried out can be set up to be activated when required, e.g. B. in driving situations in which there is undesired cooling of exhaust gas aftertreatment components.

According to the above disclosed embodiments, only one row of the cylinders i1-i6, that is, the row consisting of the cylinders i4-i6, takes part in the gas exchange from the intake pipe 402 to the exhaust pipe 416 and vice versa. Although a design of this type provides advantages, it is also contemplated that, in one embodiment, the other or both banks of cylinders participate in the gas exchange in one of the directions described in accordance with the present invention. Furthermore, the use of a twin-flow turbine is not required, but exhaust gases from all combustion chambers of the internal combustion engine can be arranged to be passed through a single line before they reach the turbine. It is also possible to direct the air flow from the engine intake side to a position downstream of the turbocharger or even downstream of one or more of the exhaust gas aftertreatment components, but upstream of at least one such component.

Furthermore, according to the above embodiments, a single EGR circuit is used for gas flow in both directions. This is very beneficial. According to one embodiment, however, separate circuits can be used for the air diversion or the recirculation of exhaust gases.

Finally, the present invention was exemplified for a motor vehicle. However, the invention is applicable to any type of vehicle, such as. B. Aircraft and watercraft. The invention is also applicable for use in combustion plants. The exhaust gas aftertreatment can also include further components, such as one or more particle filters, one or more oxidation catalytic converters, as is known per se. It is also contemplated that the exhaust gas aftertreatment may include none or more than one SCR catalytic converter and / or more than one or no ammonia barrier catalytic converters ASC.

Claims (19)

A method for controlling exhaust gases resulting from combustion in an internal combustion engine (101), the internal combustion engine (101) having at least one combustion chamber (i1-i6) and an intake side (402) for taking in air for use in the combustion, wherein the internal combustion engine (101) is also set up to produce exhaust gases, resulting from the combustion, the method comprising: - when the internal combustion engine (101) is performing at least a first work, providing an air flow from the intake side (402) for mixing with exhaust gases resulting from the combustion, the air flow being the at least one combustion chamber (i1-i6) bypasses, and - if the internal combustion engine (101) performs a second work that is less than the first work, recirculating at least part of the exhaust gases resulting from the combustion to the intake side (402 ), wherein the method is characterized by the following: - providing the air flow for mixing with the exhaust gases, only when an internal combustion engine speed is lower than a first internal combustion engine speed, or / and - providing the air flow for mixing with the exhaust gases, only when the altitude of a vehicle (100) exceeds a first altitude, the at least one combustion chamber (i1-i6) being a combustion chamber of a combustion motors (101) in the vehicle (100). Procedure according to Claim 1 further comprising: determining whether the temperature of exhaust gases resulting from combustion may be detrimental to a component exposed to the exhaust gases, and providing a flow of air to mix with the exhaust gases when the temperature of the exhaust gases can be harmful to the component. Procedure according to Claim 1 or 2 further comprising: providing the air flow to mix with the exhaust gases only when an engine load is above a first engine load. Method according to one of the Claims 1 - 3 further comprising: mixing the air flow with the exhaust gases before the exhaust gases reach at least one component (202, 203, 204) for treating the exhaust gases. Method according to one of the Claims 1 - 4th , the internal combustion engine (101) comprising a plurality of combustion chambers (i1-i6), the combustion chambers (i1-i6) being divided into n groups, each group comprising a separate exhaust gas line for exhaust gases resulting from the combustion, the method furthermore comprises: providing the air flow to lines of at most n-1 of the groups. Procedure according to Claim 5 further comprising, downstream of the mixing of the air flow with exhaust gases from the at most n-1 groups of the plurality of combustion chambers (i1-i6): mixing exhaust gases from all of the n groups of combustion chambers to form a combined exhaust gas flow, the combined Exhaust gas flow is set up to flow through at least one component (202, 203, 204) for treating the exhaust gas flow. Method according to one of the Claims 1 - 6th which further comprises: - recirculating at least a part of the exhaust gases resulting from the combustion to the suction side (402) when the internal combustion engine (101) has performed an average work that is at most the second work for a first period of time Has. Method according to one of the Claims 1 - 7th which further comprises: - recirculation of at least a part of the exhaust gases resulting from the combustion to the intake side (402) when essentially no combustion takes place in the at least one combustion chamber (i1-i6). Method according to one of the Claims 1 - 8th which further comprises: recirculating the exhaust gases without actively cooling the recirculated exhaust gases. Method according to one of the Claims 1 - 9 , wherein the internal combustion engine (101) comprises a plurality of combustion chambers (i1-i6), the method further comprising: - Recirculation of exhaust gases from only a subset of the plurality of combustion chambers to the intake side of the internal combustion engine. Method according to one of the Claims 1 - 10 which further comprises: controlling the recirculation of the exhaust gas flow by throttling exhaust gases resulting from the combustion and / or throttling intake air which is supplied to the combustion. Method according to one of the Claims 1 - 11 which further comprises: providing the air flow through a first conduit from the intake side to the exhaust gases. Procedure according to Claim 12 further comprising: returning the exhaust gases to the suction side through the first conduit. Procedure according to Claim 12 or 13th , wherein the first line has one end towards the intake side and one end towards an exhaust line, the method further being set up as follows If exhaust gases are not recirculated and an air flow is not supplied to the exhaust gases: closing the first conduit which is closer to or is substantially located at the end facing the exhaust conduit. Method according to one of the Claims 1 - 14th which further comprises: - controlling the air flow for mixing with the exhaust gases and / or the recirculation of exhaust gases based on a temperature of the exhaust gases and / or one or more exhaust gas aftertreatment components. Computer program comprising program code which, when the program code is executed in a computer, causes the computer to carry out the method according to one of the Claims 1 - 15th executes. Computer program product comprising a computer readable medium and a computer program according to Claim 16 wherein the computer program is contained in the computer readable medium. A system for controlling exhaust gases resulting from combustion in an internal combustion engine (101), the internal combustion engine (101) having at least one combustion chamber (i1-i6) and an intake side (402) for taking in air for use in the combustion, wherein the internal combustion engine (101) is further configured to emit exhaust gases resulting from the combustion, the system comprising: - Means for providing an air flow from the intake side (402) for mixing with exhaust gases resulting from the combustion, the air flow bypassing the at least one combustion chamber (i1-i6) when the internal combustion engine (101) is performing at least a first work, and - means for recirculating at least a part of the exhaust gases resulting from the combustion to the suction side (402) when the internal combustion engine (101) is performing a second work which is less than the first work, the system being characterized by the following : - Means for providing the air flow for mixing with the exhaust gases only when an internal combustion engine speed is lower than a first internal combustion engine speed, and / or - Means for providing the air flow for mixing with the exhaust gases only when the altitude of a vehicle (100) exceeds a first altitude, the at least one combustion chamber (i1-i6) being a combustion chamber of an internal combustion engine (101) in the vehicle (100) . Vehicle, which is characterized by the fact that it is a system according to Claim 18 includes.

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