DE102016011139A1 - Method for operating an internal combustion engine of a motor vehicle - Google Patents

Abstract

The invention relates to a method for operating an internal combustion engine (10) of a motor vehicle during a journey of the motor vehicle, in which by means of at least one compressor (28) compressed air, which flows through an intake tract (16) of the internal combustion engine (10), wherein at least a part the compressed air is branched off from the intake tract (16) and introduced into an exhaust tract (22) through which exhaust gas of the internal combustion engine (10) flows at at least one introduction point (E), and wherein the introduction point (E) upstream of one in the exhaust tract (22) arranged NOx accumulation catalytic converter (46) is arranged, with the steps of determining at least one parameter which characterizes at least one part of the environment of the motor vehicle ahead of the motor vehicle, and introducing the compressed air into the exhaust tract (22) in dependence on the determined parameter.

Description

The invention relates to a method for operating an internal combustion engine of a motor vehicle, in particular a motor vehicle, according to the preamble of patent claim 1.

Such a method for operating an internal combustion engine of a motor vehicle, in particular a motor vehicle, for example, is already the DE 100 53 674 A1 to be known as known. The internal combustion engine is operated during a drive of the motor vehicle. In the method, air, which flows through an intake tract of the internal combustion engine, is compressed by means of at least one compressor. Furthermore, in the method, at least part of the compressed air is branched off from the intake tract and introduced into at least one discharge point in an exhaust tract through which exhaust gas of the internal combustion engine can flow. In this case, the discharge point is arranged upstream of a NOx storage catalytic converter arranged in the exhaust gas tract. The NOx storage catalytic converter is also referred to as nitrogen oxide storage catalytic converter or NSK and used to store or temporarily store any nitrogen oxides contained in the exhaust gas in the NSK.

Further, the DE 10 2004 005 072 A1 a method for regenerating an exhaust aftertreatment system, in particular a particulate filter, an internal combustion engine arranged in the vehicle with regeneration cycles controlled by a control device.

Object of the present invention is to develop a method of the type mentioned in such a way that a particularly efficient operation of the internal combustion engine can be realized.

This object is achieved by a method having the features of patent claim 1. Advantageous embodiments with expedient developments of the invention are specified in the remaining claims.

In order to develop a method specified in the preamble of claim 1 such that a particularly efficient and thus fuel-efficient operation of the internal combustion engine can be realized, the method comprises according to the invention a first step in which at least one parameter is determined, which at least one of the motor vehicle during the Ride ahead part of the environment of the motor vehicle characterized. Furthermore, the method according to the invention comprises a second step, in which the compressed air is introduced into the exhaust gas tract as a function of the determined parameter.

The parameter comprises, for example, a speed limit which precedes the motor vehicle and / or a course of a roadway for the motor vehicle. Since the partial area is ahead of the motor vehicle during the journey, the parameter is determined in a forward-looking manner. This is to be understood that the motor vehicle during a first time or during a first time period, at which or during which the parameter is determined, has not yet reached the partial area characterized by the parameter or not yet driven, but the motor vehicle is only in near Future, ie at a second time following the first time or during a second time period following the first time span, reach or drive the partial area. This predictive determination of the at least the partial region of the environment characterizing parameter is also referred to as predictive driving.

By predictively determining the parameter, the operation of the internal combustion engine, in particular the introduction of the compressed air into the exhaust tract, can already be adapted to the subarea before the motor vehicle has actually reached the subarea. As a result, for example, the introduction of the compressed air into the exhaust gas tract can be started before the motor vehicle has reached the partial area, so that, for example, the introduction of the air into the exhaust gas tract has already been completed on reaching the partial area or shortly thereafter. Furthermore, on the basis of the parameter, for example, an introduction of the compressed air into the exhaust gas tract can be omitted. On the basis of the parameter, it can be determined in particular whether advantageous or favorable conditions prevail during or after reaching the partial region in order to introduce the compressed air into the exhaust gas tract. On the basis of the parameter, it can then be decided, for example, whether the introduction of the air into the exhaust gas tract is already started before reaching the subarea, in particular in such a way that the introduction of the air into the exhaust gas tract has already been completed on reaching the subarea or if the initiation of the submission Air in the exhaust system remains so long until the motor vehicle has left the section behind. Furthermore, it can be determined on the basis of the parameter, for example, that the subarea enables particularly favorable conditions which enable a particularly advantageous introduction of the compressed air into the exhaust gas tract.

The invention is based in particular on the following finding: Internal combustion engines, in particular Otto engines with low-consumption lean-burn process (superstoichiometric, beam-guided Gemischbildungs- or combustion process) are used in motor vehicles, especially cars, to enable, for example, a particularly efficient operation and thus keep the fuel consumption and consequently the CO ₂ emissions very low to be able to. A lean burn process is understood to mean a superstoichiometric combustion process or a superstoichiometric operation, the internal combustion engine being operated with excess air. Thus, the combustion air ratio λ is more than 1.

When working with excess air internal combustion engines, in particular gasoline engines, the exhaust aftertreatment by means of a three-way catalyst to reduce nitrogen oxide emissions is usually not sufficient. The exhaust aftertreatment for the superstoichiometric operation, which is also referred to as lean operation, therefore usually takes place by means of at least one NOx storage catalytic converter (NSK). The nitrogen oxide emissions or nitrogen oxides (NOx) possibly contained in the exhaust gas can be stored up to a certain level or up to a certain degree of loading in the NOx storage catalytic converter, which is also referred to as nitrogen oxide storage catalytic converter. If the degree of loading of the nitrogen oxide storage catalyst is exhausted or exhausted, regeneration of the NSK is then required. Such regeneration of the NSK is usually achieved by a substoichiometric operation of the internal combustion engine, which may result in increased fuel consumption. The amount of nitrogen oxides which can be stored in the NSK is, in particular given a given volume of the nitrogen oxide catalyst, in particular dependent on the operating temperature of the NSK. Usually, the NSK has a temperature range in which a particularly large amount of nitrogen oxides can be stored in the nitrogen oxide storage catalyst. This temperature range is also referred to as a working window, where usually the working window is in a temperature range of 250 ° C inclusive including up to 500 ° C.

One problem with the use of a nitrogen oxide storage catalyst is high exhaust gas temperatures, resulting in high temperatures of the nitrogen oxide storage catalyst. Such high temperatures can occur, for example, when driving with higher engine loads, in particular during acceleration processes and / or when driving at higher speeds. Then the nitrogen oxide storage catalyst can not be operated in its advantageous working window, so that a sufficient storage of nitrogen oxides in the NSK is no longer possible. In order nevertheless to avoid excessive nitrogen oxide (NOx) emissions is switched at higher loads and / or heated exhaust tract to an operation with homogeneous stoichiometric mixture or there can be no switch to the low-consumption lean operation. The limited storage capacity at higher exhaust gas temperatures also leads to a higher regeneration frequency in the upper part of the working window of the NSK, which can additionally increase the operating temperature of the nitrogen oxide storage catalytic converter and the fuel consumption.

These problems and disadvantages can be avoided in the context of the method according to the invention, since by introducing the compressed air into the exhaust tract, wherein the compressed air at the upstream of the nitrogen oxide storage catalyst arranged discharge point is introduced into the exhaust system, the exhaust gas temperature before the NSK lowered or can be kept very low. As a result, the temperature of the nitrogen oxide storage catalyst itself can be kept low and thus maintained, for example, in the working window, especially at higher engine loads of the internal combustion engine. The compressed air is used in particular as fresh air, which is introduced at the point of introduction and thus upstream of the NSK, that is, upstream of the NSK into the exhaust gas tract and thus into the exhaust gas.

Due to the cooling air introduced into the exhaust tract, the NSK can thus be held in its advantageous working window even at higher loads. Furthermore, the NSK can be brought into or be in a favorable temperature working window by the introduction or injection of air, for example, acting as cold air, whereby the nitrogen oxide emissions can be kept particularly low.

The inventive method thus enables the setting of the low-consumption lean operation, especially in real driving operation with a particularly wide range of operating conditions or time shares.

By means of the compressor, the air is compressed, for example, to a boost pressure. To generate the boost pressure is to spend energy, so preferably the operating time with active cooling is to be kept as low as possible. Active cooling is to be understood as the introduction of the air into the exhaust gas tract, since in this way the NSK is deliberately or actively cooled by means of the air introduced into the exhaust gas tract. By increasing the lean fraction of the total operating time of the internal combustion engine, a fuel economy advantage is to be expected overall. Due to the Due to the higher storage capacity of the NSK due to temperature, a decrease in the frequency of regeneration and thus an additional consumption-related or nitrogen oxide emission advantage are to be expected. For example, it is conceivable to activate the cooling of the NSK only in certain driveline boundary conditions, for example, play in engine map areas in which the lean operation by the internal combustion engine is possible, but is to be avoided by the temperature of the NSK. Furthermore, the cooling of the NSK by introducing the compressed air into the exhaust tract can advantageously be for the aging of the exhaust tract, which is also referred to as an exhaust system, so that excessive aging of the exhaust tract can be avoided.

By predictively determining the parameter and thereby enabling predictive operation of the internal combustion engine, the fuel consumption and thus the CO ₂ emissions can be kept particularly low. In particular, route-specific data is used for this purpose which takes into account the subarea lying ahead as well as in each case a further subarea in which the motor vehicle is currently located.

This makes it possible, for example, to determine a current gradient or a current gradient and an upcoming gradient or an upcoming gradient from environmental information. Taking into account the operating strategy of the exhaust tract is calculated, for example, from engine control variables, in particular from the engine power, whether the lean burn process can be used. As a result, for example, a probability can be calculated whether the active cooling of the NSK is meaningful or favorable. Furthermore, for example, current and upcoming speed limits can be determined, so that, for example, a probability is known in advance whether the lean burn process can be used. As a result, the probability of whether the cooling of the NSK makes sense can be calculated. Furthermore, it is possible to determine a future and possibly a current traffic situation. If, for example, it is determined on the basis of the parameter that the motor vehicle is preceded by a traffic jam during its drive, then the active cooling of the NSK can be prevented or carried out such that the cooling is already completed when the traffic jam is reached. Only when the above-mentioned probability or probabilities exceed or exceed a certain threshold is the active cooling of the NSK activated in order to avoid unnecessary introduction of air into the exhaust tract and thus unnecessary cooling of the NSK. It may thus be more favorable in the overall balance to maintain the stoichiometric or substoichiometric operation without refrigeration, rather than cooling, since lean operation will then probably not be usable due to the route profile. Thus, on the basis of the parameter, for example, it is also possible to switch over between the superstoichiometric or substoichiometric operation of the internal combustion engine.

Further advantages, features and details of the invention will become apparent from the following description of a preferred embodiment and from the drawing. The features and feature combinations mentioned above in the description as well as the features and feature combinations mentioned below in the figure description and / or alone in the single figure can be used not only in the respectively indicated combination but also in other combinations or alone, without the frame to leave the invention.

The drawing shows in the single figure a schematic representation of an internal combustion engine, which is operated by means of a method according to the invention.

The single figure shows a schematic representation of a whole with 10 designated internal combustion engine of a motor vehicle, which by means of the internal combustion engine 10 is drivable. The motor vehicle is designed for example as a motor vehicle, in particular as a passenger car. From the figure it can be seen that the internal combustion engine 10 an example designed as a cylinder housing engine housing 12 comprising, by which several present as a cylinder 14 trained combustion chambers of the internal combustion engine 10 are formed or limited. During a fired operation of the internal combustion engine 10 be the combustion chambers (cylinder 14 ) Air and a fuel, in particular a liquid fuel, supplied, so that in the respective cylinder 14 a fuel-air mixture is created. This fuel-air mixture is in each cylinder 14 burned, from which exhaust gas of the internal combustion engine 10 results.

The internal combustion engine 10 in this case comprises an air intake through the intake tract 16 , by means of which the intake tract 16 flowing air to the and in particular into the cylinder 14 to be led. It is in the intake 16 an air filter 18 arranged, by means of which the intake tract 16 air flowing through is filtered. Further, in the intake tract 16 an air mass meter 20 arranged, by means of which a quantity, in particular a mass, of the intake tract 16 flowing through and the cylinders 14 can be determined to be supplied air. For example, the air mass meter 20 designed as a hot-film air mass meter.

The internal combustion engine 10 further comprises an exhaust tract through which the exhaust gas can flow 22 , which is also referred to as exhaust system. By means of the exhaust tract 22 is the exhaust from the cylinders 14 dissipated. Furthermore, the internal combustion engine includes 10 at least one exhaust gas turbocharger 24 which is one in the exhaust tract 22 arranged and driven by the exhaust turbine 26 and one in the intake tract 16 arranged compressor 28 for compacting the intake tract 16 flowing air. The compressor 28 is from the turbine 26 drivable, wherein by driving the compressor 28 the intake tract 16 air flowing through the compressor 28 is compressed. Because the turbine 26 from the exhaust gas of the internal combustion engine 10 can be driven, energy contained in the exhaust gas can be used to compress the air. This is a particularly efficient operation of the internal combustion engine 10 realizable. By compressing the air, the air is heated. Nevertheless, to realize a particularly high degree of supercharging, is in the intake 16 a charge air cooler 30 arranged, by means of which the compressed and thus heated air is cooled or can be cooled. The compressed air is also referred to as charge air, so supplying the cylinders 14 with the compressed air is also referred to as charging or charging.

In the intake tract 16 is also a throttle 32 arranged, by means of which, for example, one of the cylinders 14 can be adjusted to be supplied amount of air.

By means of the compressor 28 the air is compressed, for example, to a boost pressure, wherein the boost pressure is adjustable. For this purpose, for example, a bypass device 34 with at least one bypass line 36 provided, the bypass line 36 also referred to as waste gate or waste gate line. About the bypass 36 can be at least part of the exhaust tract 22 flowing through the turbine exhaust 26 handle that so that's the bypass 36 exhaust gas flowing through the turbine 26 does not drive. To a the bypass line 36 Adjusting the amount of exhaust gas flowing through is in the bypass line 36 a valve 38 arranged, which is also referred to as waste gate valve.

The internal combustion engine 10 further comprises a feed line functioning as a bypass line 38 , which at a branch point A fluidly with the intake tract 16 and at a discharge point E fluidly with the exhaust gas tract 22 connected is. The administration 38 in this case has a length which is designated, for example, L _bypass . By means of the feed line 38 At the branching point A, at least a part of the by means of the compressor can 28 Doped compressed air and into the supply line 38 be initiated. The the feed line 38 flowing through, compressed and by means of the intercooler 30 cooled air is supplied by means of the supply line 38 to the exhaust tract 22 and in particular led to the discharge point E. The the feed line 38 air flowing through can at the point of introduction E from the supply line 38 off and into the exhaust tract 22 flow. The from the supply line 38 off and into the exhaust tract 22 At the inlet point incoming air is for example from the exhaust tract 22 flowed through exhaust gas. The feed line 38 is a valve 40 assigned, by means of which, for example, a supply line 38 flowing through amount of air is adjustable.

Furthermore, the internal combustion engine comprises 10 an exhaust aftertreatment device 42 for after-treatment of the exhaust gas, so that the exhaust aftertreatment device 42 in the exhaust tract 22 (Exhaust system) is arranged. The exhaust aftertreatment device 42 includes, for example, a first catalyst 44 , which in the flow direction of the exhaust gas through the exhaust tract 22 downstream of the turbine 26 and upstream of the discharge point E is arranged. The catalyst 44 is designed for example as a three-way catalyst. It is conceivable that the three-way catalyst has the ability to store nitrogen oxides contained in the exhaust gas (NOx), so that the catalyst 44 For example, it may be formed as a three-way NOx storage catalyst.

The exhaust aftertreatment device 42 further includes a NOx storage catalyst 46 which is downstream of the catalyst 44 is arranged. The NOx storage catalyst 46 is also referred to as nitrogen oxide storage catalyst or as NSK, wherein in the exhaust possibly contained nitrogen oxides in the NSK (NOx storage catalyst 46 ) can be stored at least temporarily.

To a particularly efficient and thereby fuel consumption and low-emission operation of the internal combustion engine 10 to realize, is the discharge point E in the flow direction of the exhaust gas through the exhaust tract 22 upstream of the NOx storage catalytic converter 46 arranged.

As part of a method for operating the internal combustion engine 10 It is thus intended, at least the intake tract 16 air flowing through the compressor 28 to compress and at least some of the compressed air from the intake system 16 by means of the supply line 28 branch off and arranged at the upstream of the NSK discharge point E in the exhaust tract 22 initiate.

By at the discharge point E in the exhaust tract 22 incoming air can be the exhaust gas and thus the NSK - as the NOx storage catalyst 46 is arranged downstream of the discharge point E - be kept particularly low, so that the internal combustion engine 10 For example, in large areas of their characteristic map in a superstoichiometric operation, that can be operated in a lean operation.

From the figure it can be seen that the NOx storage catalyst 46 is arranged at a distance Ab to the point of introduction E, wherein this distance is also denoted by L _distance .

Further, in the exhaust tract 22 a temperature sensor 48 arranged, by means of which a temperature of the exhaust gas upstream of the NSK and downstream of the discharge point E can be detected. In addition, in the exhaust tract 22 a nitric oxide sensor 50 arranged, by means of which a nitrogen oxide content of the exhaust gas downstream of the NSK can be detected.

In other words, by means of the nitrogen oxide sensor 50 an amount of nitrogen oxides possibly contained in the exhaust gas is detected.

The method of the internal combustion engine is performed during a journey of the motor vehicle, which while driving by means of the internal combustion engine 10 is driven.

In order to be able to realize a particularly efficient and thus fuel-efficient and low-emission operation of the internal combustion engine, it is provided within the scope of the method that at least one parameter is determined. The parameter characterizes a partial region of the surroundings of the motor vehicle which lies ahead of the motor vehicle during the journey. Alternatively or additionally, the parameter may characterize, for example, a current state of the motor vehicle while driving or a current driving situation or a current driving state of the motor vehicle. Furthermore, it is provided in the method that the compressed air in the exhaust tract 22 is initiated depending on the determined parameter.

The determination of the parameter characterizing the preceding subarea of the environment of the motor vehicle is also referred to as predictive determination of the parameter, since the motor vehicle has not yet reached or is not yet driving the subregion ahead characterized by the parameter while the vehicle is driving, but instead with one certain probability will reach in the future. By means of this predictive determination, for example, the operation of the internal combustion engine 10 in particular with regard to the introduction of the air into the exhaust tract 22 and thus with regard to a cooling of the exhaust gas and of the NSK effected by the introduced air, to be adapted to the partial area at a time or during a time period at which or during which the motor vehicle has not yet reached the partial area. The partial area comprises, for example, a roadway, which will be used by the motor vehicle in the near future. In this case, the parameter characterizes or comprises, for example, a speed limit which lies ahead of the motor vehicle and which currently does not apply to the motor vehicle, but will apply in the near future. Alternatively or additionally, the parameter may include or characterize a course of the roadway, so that it can be detected, for example based on the parameter, whether the motor vehicle will go down or up a slope at or after reaching the partial area. On the basis of the parameter, a load or a load state of the internal combustion engine can thus be determined in a forward-looking manner, which currently does not yet have the anticipated determined load or the anticipated determined load state, but will then have when the motor vehicle has reached the partial area. As a result, it can be determined on the basis of the parameter, for example, whether it is advantageous for realizing a low-emission operation before reaching the partial area, the air at the discharge point E in the exhaust system 22 introduce and thus cool the NSK.

The parameter is detected, for example, by means of an environmental sensor system of the motor vehicle, for example, by detecting the partial area ahead of the motor vehicle by means of the environmental sensor system.

Alternatively or additionally, it is conceivable to determine the parameter on the basis of data, wherein the motor vehicle receives the data which is provided by at least one electronic computing device different from the motor vehicle, in particular wirelessly. The electronic computing device that is different from the motor vehicle may, for example, be a server, in particular a stationary server of an infrastructure, wherein the server wirelessly provides the data via a corresponding communication module. Alternatively or additionally, it is conceivable that the electronic computing device is an electronic computing device, in particular a control device, another motor vehicle that is different from the motor vehicle. Thus, the data, for example, in the context a vehicle-to-infrastructure communication and / or as part of a vehicle-to-vehicle communication and received by the motor vehicle.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 10053674 A1 [0002]
• DE 102004005072 A1 [0003]

Claims (7)

Method for operating an internal combustion engine ( 10 ) of a motor vehicle during a journey of the motor vehicle, in which by means of at least one compressor ( 28 ) Air, which is an intake tract ( 16 ) of the internal combustion engine ( 10 ), is compressed, wherein at least a portion of the compressed air from the intake tract ( 16 ) and at at least one introduction point (E) into one of exhaust gas of the internal combustion engine ( 10 ) throughflowable exhaust tract ( 22 ), and wherein the introduction point (E) upstream of a in the exhaust tract ( 22 ) arranged NOx storage catalyst ( 46 ), characterized by the steps: - determining at least one parameter which characterizes at least one subarea of the surroundings of the motor vehicle which lies ahead of the motor vehicle; and - introducing the compressed air into the exhaust tract ( 22 ) depending on the determined parameter. A method according to claim 1, characterized in that the parameter comprises at least one motor vehicle ahead speed limit. A method according to claim 1 or 2, characterized in that the parameter comprises a course of a roadway for the motor vehicle. Method according to one of the preceding claims, characterized in that the parameter comprises a traffic situation ahead of the motor vehicle. Method according to one of the preceding claims, characterized in that the parameter is determined by means of an environmental sensor system of the motor vehicle. Method according to one of the preceding claims, characterized in that the parameter is determined as a function of at least one of the motor vehicle different electronic computing device provided data which are received by the motor vehicle, in particular wirelessly. Method according to one of the preceding claims, characterized in that the internal combustion engine ( 10 ) is operated in a superstoichiometric operation.

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