DE102015013284A1 - Method for operating a vehicle and vehicle - Google Patents

Abstract

The invention relates to a method for operating a vehicle, in which by means of at least one exhaust aftertreatment device of an exhaust system (10) of the vehicle, the exhaust gas of an internal combustion engine of the vehicle is treated. In this case, a presence of a local and / or time-limited requirement for the emissions of the vehicle is detected, compliance with a current operating mode of the internal combustion engine and / or the exhaust system (10) is not possible. Then, it is switched to a modified operating mode, in which compliance with the currently applicable requirement for the emissions of the vehicle can be achieved. Furthermore, the invention relates to a vehicle.

Description

The invention relates to a method for operating a vehicle, in which by means of at least one exhaust aftertreatment device of an exhaust system of the vehicle, the exhaust gas of an internal combustion engine of the vehicle is treated. Furthermore, the invention relates to a vehicle.

Vehicles, in particular vehicles with an internal combustion engine drive, must comply with legally prescribed emission requirements. These emission targets are currently specific to specific regions (such as the EU, US, or Japan) and are currently being presented and reviewed on defined vehicle or engine test bench cycles. Future plans include an additional review of real emissions using PEMS (Portable Emission Measurement System) measurement technology.

Current vehicle reconciliation strives for an optimal compromise between compliance with legal emission requirements and minimum fuel consumption.

Due to local pollution problems in agglomerations (above all due to high traffic volumes), increasingly stringent emission restrictions or entry bans for the affected areas are being discussed. Time-dependent traffic phenomena (eg traffic congestion) can also lead to a sharp increase in local emissions. Special location-dependent conditions (such as tunnels, underpasses or parking garages) can exacerbate this situation. Furthermore, specific weather phenomena (for example, stable high-pressure weather conditions) can increase the sensitivity to exhaust emissions. Thus, due to nitrogen oxide emissions, increased ozone formation may occur and smog may occur due to particulate emissions.

The emission-relevant emissions, which are the focus of these considerations, are mainly nitrogen oxides (NOx), carbon monoxide (CO), particulates and hydrocarbons (HC). Internal combustion engine drives of vehicles caused by operation cause exhaust emissions such as nitrogen oxides (NOx), carbon monoxide (CO), particulates and hydrocarbons (HC), which by downstream emission control or exhaust aftertreatment devices of an exhaust system of the respective vehicle in harmless or less harmful compounds, such as water, CO ₂ or nitrogen, to be converted.

The optimum mode of operation of the exhaust gas purification systems is dependent on various parameters such as, for example, the raw emissions of the internal combustion engine, the exhaust gas temperature, the space velocity and the like. Above all, the parameters of raw emission quantity and exhaust gas temperature have a dominant influence on the emissions of the exhaust system.

Conventional catalytic exhaust gas purification units or exhaust aftertreatment devices have an age-dependent minimum temperature at which a reaction which reduces the content of pollutants in the exhaust gas can take place or proceeds to a certain minimum extent. This minimum temperature is also referred to as light-off temperature, light-off temperature or LO temperature. As the catalyst ages, the corresponding temperature threshold shifts to higher temperatures.

The DE 196 29 163 C1 describes a method in which, with cold exhaust gas catalyst, an operation of an internal combustion engine is set, in which a late injection takes place. Once a temperature of the catalytic converter has reached a value within a predeterminable temperature range for an effective catalytic nitrogen oxide reduction, the operation of the internal combustion engine is switched to a more economical early injection.

Furthermore, the describes WO 99/50549 A2 an engine system with an internal combustion engine and an electronic engine control and a control device for a cleaning device for post-treatment of the exhaust gas. This is to be ensured by a bi-directional signal transmission between the engine control and the control device that at the same time emission limits are met and the lowest possible fuel consumption is achieved.

Object of the present invention is to provide an improved method of the type mentioned above and a corresponding vehicle.

This object is achieved by a method having the features of patent claim 1 and by a vehicle having the features of patent claim 10. Advantageous embodiments with expedient developments of the invention are specified in the dependent claims.

In the method according to the invention, it is first of all determined whether there is a particular local and / or time-limited special requirement on the emissions of the vehicle, compliance with which is not possible with a current operating mode of the internal combustion engine and / or the exhaust system, such as a local environmental zone. If this is the case, it is switched to a modified operating mode, in which compliance with the currently applicable special requirements for the emissions of the vehicle can be achieved. In this way it is possible, when driving through areas with different special emission requirements, such as driving in local environmental zones, to comply with local or temporary emission limits. Thus, an improved method is provided. In the context of the invention, a particular requirement for the emissions of a vehicle is to be understood as a locally and / or time-limited requirement for the emissions of a vehicle, in particular the exhaust emissions or the noise emissions of a vehicle, which exceeds the requirements set out in statutory emission regulations, such as For example, the emission standard Euro-6, specified requirements.

• – eine Hinweistafel,
• – ein Wechselverkehrszeichen,
• – ein elektronisches Schrankensystem,
• – Radiomeldungen,
• – GPS-Daten,
• – Durchsagen, die von einem eine von einem Nutzer des Fahrzeugs erfassbar sind und insbesondere in einem Tunnel ausgegeben werden,
• – über das Internet erhältliche Informationen und
• – ein Car-to-Car-Communication-System zur Erfassung der Verkehrsdichte und/oder Infrastruktur.

In one embodiment of the invention, external information sources are used to determine the presence of the local and / or time-limited special requirement on the emissions of the vehicle. External sources of information within the scope of the invention may be:

• - a billboard,
• A variable message sign,
• - an electronic barrier system,
• - radio messages,
• - GPS data,
• Announcements which can be registered by a user and are in particular issued in a tunnel,
• - information available on the internet and
• - A car-to-car communication system for recording traffic density and / or infrastructure.

Also an existing in the vehicle optical or ultrasonic / radar system for detecting the density of construction or for parking parked vehicles, for example by a camera or parking aids and / or a meter for measuring the ambient air quality and / or at least one environmental variable, in particular an ambient air pressure and Within the scope of the invention, an ambient temperature and / or precipitation may be used for determining or at least assessing the likelihood of a particular local and / or time-limited requirement for the emissions of the vehicle.

It can also be determined on the basis of driving profiles that there are traffic situations associated with increased emissions, such as traffic jams. Here, too, a tightening of emission requirements can be expected so that they can be accommodated by timely switching to the changed operating mode.

Switching to the changed operating mode can be carried out automatically, ie by means of a control device of the vehicle, or manually, ie by a user of the vehicle. For example, by manually activating the special or changed operating mode, an increased, in particular a substantially complete, conversion of environmentally harmful exhaust emissions such as NO x, CO, HC or particles can be ensured. In particular, by switching to the changed operating mode, an emission of nitrogen oxides can be reduced.

• – eine Abgastemperatur, insbesondere durch Wählen eines bestimmten Gangs eines Getriebes des Fahrzeugs und/oder durch Verändern eines Ladedrucks und/oder durch Verändern einer Abgasrückführungsrate, verändert wird und/oder
• – eine Beaufschlagung eines Stickoxidspeicherkatalysators des Fahrzeugs mit einem fetten Gemisch verändert und/oder
• – ein Einbringen eines Reduktionsmittels zum Reduzieren von Stickoxiden in das einem SCR-Katalysator des Fahrzeugs zugeführte Abgas verändert

wird.In one embodiment of the invention, by switching to the changed operating mode, an emission of nitrogen oxides can be reduced by

• An exhaust gas temperature, in particular by selecting a specific gear of a transmission of the vehicle and / or by changing a boost pressure and / or by changing an exhaust gas recirculation rate, is changed and / or
• - Modified and / or an admission of a nitrogen oxide storage catalyst of the vehicle with a rich mixture
• Changing an introduction of a reducing agent for reducing nitrogen oxides into the exhaust gas supplied to an SCR catalytic converter of the vehicle

becomes.

Furthermore, acoustic emissions of the vehicle can be changed and in particular reduced. This can be done, for example, by changing at least one parameter of the combustion taking place in the internal combustion engine and / or by operating an active sound system.

Preferably, the presence of the changed operating mode is signaled, wherein in particular on a vehicle outside an optical signal can be output, for example in the form of a flashing lamp. Additionally or alternatively, the presence of the changed operating mode can be communicated by outputting a non-visible signal, which can be detected, for example, by means of a measuring device. The signal may in particular be a radio signal. Furthermore, it is conceivable that, compared to the previous operating mode, changed, in particular reduced, noise emissions are emitted by the vehicle in order to signal the presence of the changed operating mode.

In one embodiment of the invention in the modified operating mode a age-dependent, to be reached target temperature of the at least one exhaust aftertreatment device and / or allowable raw emissions of the internal combustion engine set. Advantageously, the aging state of the exhaust gas aftertreatment device can be taken into account particularly well when setting the changed operating mode.

In one embodiment of the invention, the operating mode is switched again as soon as it is determined that the local and / or time-limited special requirement for the emissions of the vehicle is no longer valid. In this case, in particular, a lower fuel consumption can be set with respect to the changed operating mode. This is based on the knowledge that with regard to the exhaust emissions more favorable operating conditions of the internal combustion engine and the exhaust system can be accompanied by an increased fuel consumption. This is the case, for example, if, by introducing unburned fuel into the exhaust system, its temperature is increased locally in order to achieve a higher conversion performance of at least one of the exhaust gas after-treatment devices. If renewed switching of the operating mode, the sharper emission requirements are no longer present, thus a particularly low fuel consumption of the vehicle can be achieved.

The vehicle according to the invention has an exhaust system with at least one exhaust gas aftertreatment device. The vehicle includes an internal combustion engine and a control device for setting an operating mode of the internal combustion engine and / or the exhaust system. Furthermore, the vehicle has means for determining the presence of a local and / or time-limited special requirement on the emissions of the vehicle, the compliance with the current operating mode of the internal combustion engine and / or the exhaust system is not possible. Means are provided for switching to a changed operating mode in which compliance with the currently applicable special requirement for the emissions of the vehicle can be achieved, for example a rotary or push switch or a selection option provided in an operating device.

The advantages and preferred embodiments described for the method according to the invention also apply to the vehicle according to the invention.

The features and feature combinations mentioned above in the description as well as the features and feature combinations mentioned below in the description of the figures and / or in the figures alone can be used not only in the respectively specified combination but also in other combinations or in isolation, without the scope of To leave invention. Thus, embodiments are also included and disclosed by the invention, which are not explicitly shown or explained in the figures, however, emerge and can be produced by separated combinations of features from the embodiments explained.

Further advantages, features and details of the invention will become apparent from the claims, the following description of preferred embodiments and from the drawings. Showing:

1 schematically the dependence of the conversion of carbon monoxide on the temperature and the aging of a catalyst;

2 schematically an exhaust system of a vehicle, the exhaust aftertreatment devices for treating exhaust gas of an internal combustion engine of the vehicle comprises; and

3 schematically the temperature dependence of the nitrogen oxide conversion of an SCR catalyst and the influence of aging on the SCR catalyst.

As in 1 exemplified, the efficiency of the carbon monoxide conversion of an oxidation catalyst 12 which is in an exhaust system 10 a vehicle is arranged (see 2 ), a strong temperature dependence, which shifts to higher temperatures due to catalyst aging.

In an in 1 shown graphs 14 is on an abscissa 18 the temperature T is plotted on carbon monoxide conversion and on an ordinate 16 the efficiency η in the carbon monoxide conversion. A first turn 20 illustrates the conversion for a fresh oxidation catalyst 12 , Another, essentially parallel shifted to the right curve 22 illustrates the carbon monoxide conversion for the aged oxidation catalyst 12 , The light-off temperature for the non-aged oxidation catalyst 12 is in 1 through a line 24 and the light-off temperature for the aged oxidation catalyst 12 through another line 26 ,

Accordingly is off 1 It can be seen that an increase in the temperature in a region in which the oxidation catalyst 12 has its light-off temperature, leads to an increase in sales and thus to a reduction in exhaust emissions. Generally, the Exhaust emissions of the exhaust system 10 be lowered via a reduction of the raw emission level.

A method for operating a vehicle, in which locally and / or time-limited requirements for the emissions of the vehicle are taken into account, shall be described by way of example on the basis of in 2 illustrated exhaust system 10 be described for a passenger car with a designed as a diesel engine combustion engine.

The example in 2 shown exhaust system 10 comprises an electrically heatable catalyst (EHC) at exhaust aftertreatment devices 28 , the oxidation catalyst 12 or Diesel Oxidation Catalyst (DOC), a metering device 30 for introducing a reducing agent available under the brand name Adblue into the exhaust gas, a particle filter 32 and one the particulate filter 32 with downstream SCR catalyst 34 , The particle filter 32 preferably has a coating on which in a selective catalytic reduction reaction (SCR = Selective Catalytic Reduction) nitrogen oxides are converted from the exhaust gas with ammonia to nitrogen and water, and is therefore preferred as an SCR-coated particulate filter 32 (SDPF) trained. Other options, not shown, such as an ammonia trap catalyst downstream of the SCR catalyst 34 , are also conceivable.

The conversion performance with respect to hydrocarbons and carbon monoxide on the oxidation catalyst 12 is mainly from the exhaust gas temperature upstream of the oxidation catalyst 12 dependent (cf. 1 ). A fresh oxidation catalyst 12 usually shows a complete conversion performance from a temperature of about 200 ° C. In aged systems, this minimum temperature or light-off temperature shifts to a level of about 250 ° C. Temperatures above 600 ° C lead to increased aging of the oxidation catalyst 12 and should, if possible, be time-limited.

The conversion performance in terms of nitrogen oxides (NOx) of the SDPF / SCR system, ie on the coated particle filter 32 and in the SCR catalyst 34 , depends mainly on the NOx raw emissions, the Adblue dosing and in particular on the exhaust gas temperature upstream of the particulate filter 32 from. For unaged catalyst systems here temperatures between 220 ° C-500 ° C for a full conversion are favorable (optimal are 250 ° C-400 ° C). A thermally aged system exhibits a limited optimal window of action between 250 ° C-450 ° C (preferably between 250 ° C-400 ° C).

3 shows by way of example the NO x conversion of fresh and aged SCR systems as a function of the temperature. In another, in 3 shown graphs 36 is accordingly on an abscissa 38 again the temperature T plotted in degrees Celsius, but on an ordinate 40 the nitrogen oxide conversion in percent. A first turn 42 illustrates the temperature dependence of nitrogen oxide conversion for a fresh SCR catalyst 34 and a second curve 44 same for an aged SCR catalyst 34 , According to the curve 44 the temperature window is narrower, in which the aged SCR catalyst 34 or the coated particle filter 32 and the SCR catalyst 34 comprehensive SCR system shows good conversion of nitric oxide.

In addition, to ensure optimal NOx conversion, the metered AdBlue amount can be chosen sufficiently high. It can therefore at least the amount for a stoichiometric NOx conversion via the metering device 30 in the exhaust system 10 be introduced. Preferably, however, a factor of 1.5 can be applied to the amount necessary for the stoichiometric conversion of NOx, and correspondingly more Adblue can be added.

The engine emissions are mainly defined in a diesel engine by the combustion lambda, the EGR rate (exhaust gas recirculation rate), the supercharging level, the combustion center of gravity and the pressure in the common rail, from which the fuel is introduced into the cylinders of the diesel engine. By modifying these parameters, it is therefore possible to influence the raw emission quantities. Hybridization (ie electrical support for driving the vehicle) also makes it possible to change the level of raw emissions, especially during load changes. Furthermore, by varied transmission settings (ie a so-called "shift shift"), the diesel engine can be operated in different load states, each with a different level of raw emissions.

As explained in the introductory part of the present description, common vehicle reconciliations are often chosen so that the legally prescribed emission limit values of the respective region (such as the EU) are complied with. However, moving such a vehicle in areas with different emission requirements (such as local environmental zones) may result in situations where local and / or time-limited emission limits are not safely met.

For example, it is possible for an operating mode of the internal combustion engine and / or the exhaust system provided for compliance with certain emission limit values not to be able to comply with stricter emission limit values, such as may be valid for a specific region in time or locally.

In special traffic situations, such as heavy traffic or congestion, the exhaust gas temperatures can also be lower than those in 2 and 3 for the oxidation catalyst 12 or the SDPF / SCR system (which the coated particulate filter 32 and the SCR catalyst 34 includes), critical limit temperatures decrease. A sufficient conversion performance of the exhaust aftertreatment system is then no longer feasible.

By a particularly low-emission mode of operation of the exhaust system 10 On the other hand, emissions (for example, due to an operating mode leading to higher exhaust-gas temperatures) can also be reduced to values below the current limit values. Although this is generally associated with an increase in fuel consumption. However, this mode of operation can lead to the vehicle owner being able to benefit from special benefits or benefits, such as the use of bus lanes. In the opposite case, this mode of operation may lead to the avoidance of driving restrictions for special categories of vehicles, such as diesel vehicles.

A corresponding method or such a function can also be subsequently introduced or implemented in the vehicles of an existing vehicle fleet, for example in order to avoid driving bans on older vehicle inventories. This can be done, for example, by reprogramming a control device or such a control device of the respective vehicle.

In these special situations, the exhaust gas temperature can be raised as a function of age by per se known engine measures, such as a late shift of the combustion position, late post-injection, a lambda reduction and the like, resulting in optimum or sufficiently improved cleaning performance of the exhaust aftertreatment components or exhaust aftertreatment devices.

Alternatively or additionally, by electrical energization of the electrically heatable catalyst 28 the temperature at the oxidation catalyst 12 be raised. Furthermore, the raw emission output may be lowered (such as by increasing the EGR rate, resulting in a reduction of the raw emissions of NOx).

Furthermore, a reduction of the emissions may also include a reduction or change in the vehicle noise, ie the noise emissions of the vehicle. This can be done for example by means of a modified engine operation or by an active sound system.

At least some of these measures are typically associated with an increase in fuel consumption. However, they achieve an almost complete or at least a higher conversion of the environmentally harmful exhaust emissions such as NO x (NO 2), CO, HC and the like.

It can therefore be provided that upon detection of a specific emission requirement, the vehicle can change to a changed operating state or operating mode, which ensures a nearly complete emission conversion. For this purpose, even an increase in fuel consumption can be accepted.

Preferably, however, it is proposed that upon detection of a currently applicable or modified requirement for the emissions of the vehicle, the compliance with the current operating mode is not possible, a switch to a modified operating mode is made, which allows compliance with the currently applicable or amended emission requirement.

The switching can be triggered automatically and or by pressing a switch (such as a "zero-emission button"). Tripping criteria may include information boards, electronic barrier systems, radio messages, GPS data, announcements in tunnels, Internet information and the like. When detected by electronic barrier systems corresponding receiving systems are present in the vehicle. Furthermore, driving profiles and environmental parameters such as ambient air pressure or ambient temperature, precipitation and the like may be taken into account.

Thus, if a control device of the vehicle and / or the driver or another user of the vehicle receives the indication that special emission requirements apply, then, if necessary, manually and / or automatically be switched to an operating mode which enables as complete an emission reduction as possible. Preferably, at least a compliance with the specific emission requirement at least for the period of its validity for the vehicle by switching to the changed mode of operation can be achieved.

In this case, preferably the aging state of the relevant exhaust gas purification components or exhaust gas after treatment devices, in particular by means of common OBD diagnoses (OBD = on-board diagnosis) is determined, in particular in combination with models. Depending on the aging state of the exhaust aftertreatment devices, in particular those for the Compliance with the specific emission requirements preferred minimum temperatures described above adjusted by means of a modified motor tuning. Additionally or alternatively, the temperature of the oxidation catalyst 12 by activation of the electrically heatable catalyst 28 be raised.

At the same time it is favorable to lower the engine raw emission. This is illustrated, for example, by a later focus of combustion, which leads to a reduction in NOx emissions and particulate emissions. Furthermore, the transient emission behavior can be improved by reduced dynamics during positive load changes. This can be additionally positively influenced by an electrical support (ie by a temporary electromotive driving operation).

If it is detected that the special emission requirements are no longer valid, but instead new, less stringent or restrictive emission requirements are present, the operating mode is preferably switched back again. Preferably, a more favorable in terms of fuel consumption operating mode is set by means of which the new emission requirements can be met.

Furthermore, an automatic and / or manual activation, for example via a zero emission key, of a special operating state or operating mode can be provided, which ensures as complete a conversion as possible of the environmentally harmful exhaust emissions, especially of NOx, CO, HC and particles ,

By an automatic and / or manual activation (for example via the "zero-emission key") of the changed operating state or operating mode, it is also possible to set that, in particular, the emission of NO _{2 is} reduced. This can be achieved, for example, by the measures described below. Thus, a certain exhaust gas temperature can be adjusted (for example by a corresponding gear selection, the specification of a certain boost pressure, a certain EGR rate and the like). Additionally or alternatively, the strategy of enriching the mixture, which is supplied to a nitrogen oxide storage catalyst of the vehicle, may be changed. Furthermore, the exhaust gas temperature can be adjusted by changing the AdBlue dosing strategy, ie by changing the introduction of a reducing agent to reduce nitrogen oxides into the SCR catalyst 34 and / or the coated particulate filter 32 the exhaust gas supplied to the vehicle.

Also, a reduction or change in the noise emissions of the vehicle can be made if a special requirement is recognized for this. This can be done by changing the combustion or by an active sound system.

An indication of the current operating state of the vehicle can be made on the outside of the vehicle by means of an optical signal, such as a lamp, or by a signal that is not visible (for example, by emitting a radio code). Such a signal or radio signal can control the appropriate authorities, or it can be (similar to a speed measurement) automatically checked at measuring points.

The operating state or operating mode of the vehicle can also be signaled to the environment by changing the acoustics. This can be done for example by particularly low noise emissions of the vehicle.

Furthermore, an age-dependent definition of the target temperatures of the exhaust system to be achieved 10 and / or the exhaust aftertreatment devices and maximum allowable raw emissions of the diesel engine in the changed operating state or operating mode possible.

In particular, a location-dependent target emission setting can be achieved by the method described here.

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 19629163 C1 [0008]
• WO 99/50549 A2 [0009]

Claims (10)

Method for operating a vehicle, in which by means of at least one exhaust aftertreatment device of an exhaust system ( 10 ) of the vehicle, the exhaust gas of an internal combustion engine of the vehicle is treated, characterized in that a presence of a local and / or time-limited special requirement for the emissions of the vehicle is determined, compliance with a current operating mode of the internal combustion engine and / or the exhaust system ( 10 ) is not possible, being switched to a modified operating mode, in which compliance with the currently applicable special requirement for the emissions of the vehicle can be achieved. A method according to claim 1, characterized in that are used to determine the presence of the local and / or time-limited special requirement for the emissions of the vehicle external information sources. A method according to claim 1 or 2, characterized in that is switched by a control device and / or by a user of the vehicle in the changed operating mode in which a relation to the previous operating mode increased conversion of at least one exhaust gas component is achievable. A method according to claim 3, characterized in that by switching to the changed operating mode, an emission of nitrogen oxides is reduced by changing an exhaust gas temperature, by varying a boost pressure and / or by changing an exhaust gas recirculation rate of the internal combustion engine. Method according to one of claims 1 to 4, characterized in that acoustic emissions of the vehicle, in particular by changing at least one parameter of the combustion taking place in the internal combustion engine and / or by operating an active sound system, are changed. Method according to one of claims 1 to 5, characterized in that the presence of the changed operating mode is signaled. A method according to claim 6, characterized in that for signaling the presence of the changed operating mode, a signal detectable by a measuring device is output. Method according to one of claims 1 to 7, characterized in that in the changed operating mode, an age-dependent to be reached target temperature of the at least one exhaust aftertreatment device and / or allowable raw emissions of the internal combustion engine are set. Method according to one of claims 1 to 8, characterized in that the operating mode is switched again when it is determined that the local and / or time-limited requirement for the emissions of the vehicle are no longer valid. Vehicle having an exhaust system comprising at least one exhaust gas aftertreatment device ( 10 ), with an internal combustion engine and with a control device for setting an operating mode of the internal combustion engine and / or the exhaust system ( 10 ), characterized in that the vehicle has means for detecting the presence of a local and / or time-limited special requirement on the emissions of the vehicle, compliance with a current operating mode of the internal combustion engine and / or the exhaust system ( 10 ) is not possible, and means for switching to a changed operating mode, in which compliance with the currently applicable requirement for the emissions of the vehicle can be achieved.

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