DE102019008535A1 - Method for operating a motor vehicle, in particular a motor vehicle - Google Patents

Abstract

The invention relates to a method for operating an internal combustion engine (10), an exhaust gas tract (12) through which exhaust gas from the internal combustion engine (10) can flow, and an exhaust gas aftertreatment device (14) arranged in the exhaust gas tract (12) for aftertreating the exhaust gas, in which at least one component of the exhaust gas is measured downstream of the exhaust gas aftertreatment device (14) by means of a sensor device (18) of the motor vehicle, the motor vehicle also having at least one component (20, 22, 24, 26), the operation of which can influence at least the component, wherein if the component exceeds a first threshold value, at least a second threshold value, on the basis of which the component (20, 22, 24, 26) is monitored by means of on-board monitoring (30) of the motor vehicle, is tightened.

Description

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

Such a method for operating a motor vehicle is, for example, already DE 10 2004 006 992 A1 as known. In the method, the motor vehicle has an internal combustion engine and an exhaust tract through which exhaust gas from the internal combustion engine can flow. In addition, the motor vehicle comprises an exhaust gas aftertreatment device which is arranged in the exhaust tract and thus through which the exhaust gas can flow, by means of which the exhaust gas can be aftertreated. In the method, at least one component of the exhaust gas is measured by means of a sensor device of the motor vehicle. The motor vehicle also has at least one component, the operation of which influences at least the component, that is to say can be increased and / or decreased, for example.

The object of the present invention is to further develop a method of the type mentioned at the beginning in such a way that particularly low-emission operation of the motor vehicle can be implemented in a particularly advantageous manner.

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

In order to further develop a method of the type specified in the preamble of claim 1 in such a way that particularly low-emission operation of the motor vehicle, for example designed as a motor vehicle, can be implemented in a particularly advantageous manner, it is provided according to the invention that, if the component is a first, for example predefinable or predefined Exceeds threshold value, at least a second, in particular predeterminable or predetermined, threshold value, on the basis of which the component or its operation is monitored, tightened by means of on-board diagnostics (OBD) of the motor vehicle. This means that a tolerance range in which a deviation of an actual operation from a target operation of the component is tolerated or that a maximum tolerated or maximum permitted deviation of the actual operation from the target operation of the component is reduced. The feature that the at least one component of the exhaust gas is measured downstream of the exhaust gas aftertreatment device by means of the sensor device of the motor vehicle is to be understood in particular that the exhaust gas has the component downstream and thus after the exhaust gas aftertreatment device. Since the component is measured by means of the sensor device of the motor vehicle, that is, since the sensor device is a component of the motor vehicle, the component is measured using what is known as on-board measurement (OBM). According to the invention, the OBD is linked to the OBM, since when it is measured by means of the OBM that the component exceeds the first threshold value, the second threshold value used for the OBD is tightened. Thus, for example, the OBM is integrated into the OBD or vice versa in order to be able to optimize emissions and robustness compared to conventional solutions.

The feature that the component or its operation is monitored using the second threshold value is to be understood, for example, as follows: By means of the on-board monitoring, in particular during operation of the motor vehicle and in particular during operation of the component, for example at least one is -Operating value determined, which characterizes a current state or a current operation of the component. The actual operating value is compared with at least one setpoint operating value, for example by means of the on-board monitoring. For example, if the actual operating value corresponds to the target operating value or if a difference between the actual operating value and the target operating value, in particular the mathematical amount of the difference, is less than the second threshold value, the component is classified as functional or free of damage, for example. In other words, the current operation of the component corresponds to a desired target operation of the component. However, if the difference or the mathematical amount of the difference exceeds the second threshold value, the current operation of the component deviates undesirably, that is excessively, from the desired target operation, so that, for example, the component is classified as faulty. For example, the feature that the second threshold value is tightened is to be understood as meaning that the second threshold value is reduced. If, for example, a first maximum difference between the actual operating value and the target operating value is initially permitted without the component or its operation being classified as faulty, then by tightening the second threshold value, only a smaller second difference between the The actual operating value and the target operating value or the current operation and the target operation are permitted without the component being classified as faulty or is assessed. Since the tightening of the second threshold value depends on the component and takes place when the component exceeds the first threshold value, such an operation of the component and thus of the motor vehicle can be ensured by tightening the second threshold value that there are no excessive emissions, and a unnecessary early maintenance or repair of the motor vehicle can be avoided. A particularly low-emission operation of the motor vehicle can thus be ensured in a particularly advantageous manner.

In particular, the feature that the component of the exhaust gas is measured by means of the sensor device can be understood to mean that at least one quantity value is measured and thus determined by means of the sensor device, the quantity value being a proportion of the component in the exhaust gas or a quantity contained in the exhaust gas of the component characterized.

The invention is based, in particular, on the following findings: Components that may age and / or fail are usually monitored by means of the on-board diagnosis in order to avoid excessive emissions. The monitoring takes place taking into account the second threshold value, so that the respective component, also referred to as a component, is monitored against the second threshold value. If, for example, the aforementioned difference or its mathematical amount exceeds the second threshold value, also referred to as the OBD threshold value, a so-called engine control lamp (MIL) lights up in the interior of the motor vehicle. This prompts a driver of the motor vehicle to have the motor vehicle repaired or serviced in order to avoid excessively high emissions. The OBD verification is carried out on the basis of a manipulated component on a firmly defined, conditioned vehicle in order to be able to guarantee sufficient reproducibility. This verification is successful if the prescribed emissions have not been exceeded.

Usually only a single fault is considered in a limited time window. A component that usually ages slowly may be displayed too quickly as faulty, since other components compensate for the emission flow through adaptations. In the case of multiple defect patterns, the emissions could deviate from the defined test method and cannot be reproducibly detected due to the diversity and complexity.

The above-mentioned problems and disadvantages can be avoided by the invention. In the case of vehicles that have a sensor system that can measure emissions, in particular so-called final emissions, a control device evaluates, for example, whether the emissions are in an expected range. If a defined limit value is exceeded, relevant OBD threshold values, which are also referred to as error thresholds, are tightened, which can have an influence on the measured emissions. This can take place in several tightening stages, depending on the exceedance of the emission limit value. The aforementioned end emissions are to be understood in particular as meaning that, for example, the exhaust gas has the aforementioned component at a point in the exhaust gas tract, with an exhaust gas aftertreatment device of the motor vehicle not being post-treated downstream of the point in the flow direction of the exhaust gas flowing through the exhaust gas tract. In other words, the exhaust gas containing the constituent flows out of the exhaust gas tract to the surroundings of the motor vehicle without any further aftertreatment of the exhaust gas taking place.

The sensor device can comprise a nitrogen oxide sensor (NOx sensor). For example, if the nitrogen oxide sensor measures increased nitrogen oxide emissions (NOx emissions), the OBD threshold values for injectors, by means of which a particularly liquid fuel is introduced or injected into at least one combustion chamber of the internal combustion engine, for an exhaust gas recirculation device, are tightened which exhaust gas is recirculated for at least one catalytic converter, for an air mass meter and / or for other components.

• - Einhaltung der Emissionen, auch wenn mehrere Komponenten gealtert oder defekt sind, und dies über das gesamte Leben des Kraftfahrzeugs
• - längere Lebensdauer der emissionsrelevanten Komponenten (Fehleranzeige der Komponente erst bei OBD-Schwellenwertüberschreitung und Emissionsüberschreitung), da zum Beispiel durch Adaption dritte Bauteile den Emissionseinfluss kompensieren können
• - Verbesserung des sogenannten Pin-Pointings, das heißt eines Verfahrens, mittels welchem identifiziert werden kann, welche Komponente defekt beziehungsweise übermäßig gealtert ist.

The invention enables the following advantages in particular to be realized:

• - Compliance with emissions, even if several components are aged or defective, and this over the entire life of the motor vehicle
• - Longer service life of the emission-relevant components (fault display of the component only when the OBD threshold value is exceeded and the emissions are exceeded), since third components can, for example, compensate for the influence of emissions by adapting them
• - Improvement of so-called pin pointing, that is, a method by means of which it can be identified which component is defective or excessively aged.

The sensor device is, for example, a measuring box which is arranged in the region of one end or at one end of the exhaust tract. The exhaust gas can flow through the measuring box and measure the component. In particular, the measuring box measures or detects or determines respective values which the component or characterize its amount in the exhaust gas. If the constituent exceeds the first threshold, the second threshold is tightened. As a result, for example, a deviation of the current operation from the target operation by 60% is no longer permitted, but only by 30%. The component, the operation of which can influence the component, is, for example, a nitrogen oxide storage catalytic converter, an SCR catalytic converter, an introduction device for introducing a reducing agent into the exhaust gas, an exhaust gas recirculation device for recirculating exhaust gas and / or the internal combustion engine, in particular a control unit for operating, in particular controlling or regulating the internal combustion engine.

The tightening of the second threshold value leads to the fact that adaptation routines of the respective components are executed, whereby the motor vehicle adjusts itself or changes itself in such a way that excessive emissions are avoided and the MIL is activated. The background to this is that emissions, such as nitrogen oxide emissions, at the tailpipe are dependent on the work of a number of individual components. An adaptation can be provided for each of the components, which optimizes the operation of the respective individual component. With the method according to the invention, adaptations for these components can be triggered in the event of slight aging, damage or the running of the operation of individual components, so that activation of the MIL does not take place and unnecessarily early replacement of components is avoided, while at the same time excessively high emissions can be avoided.

In an advantageous embodiment of the invention it is provided that nitrogen oxides and / or unburned hydrocarbons and / or particles are measured as the constituent.

In an advantageous embodiment of the invention, it is provided that at least one injector, by means of which a fuel can be introduced into at least one combustion chamber of the internal combustion engine, and / or an exhaust gas recirculation device and / or at least part of the exhaust gas aftertreatment device and / or at least one air mass meter is used as the component becomes.

Further advantages, features and details of the invention emerge from the following description of a preferred exemplary embodiment and with reference to the drawing. The features and combinations of features mentioned above in the description as well as the features and combinations of features mentioned below in the description of the figures and / or shown alone in the single figure can be used not only in the specified combination, but also in other combinations or on their own, without the frame to leave the invention.

In the single figure, the drawing shows a schematic representation to illustrate a method according to the invention for operating a motor vehicle, in particular a motor vehicle.

A method for operating a motor vehicle, preferably designed as a motor vehicle, in particular as a passenger vehicle, is described below with reference to the single FIGURE. In the method, the motor vehicle has an internal combustion engine, also referred to as an internal combustion engine or motor 10 on, by means of which the motor vehicle can be driven. The motor vehicle also has an exhaust tract, also referred to as an exhaust system 12th on which of the exhaust gas of the internal combustion engine 10 is permeable. It is in the exhaust tract 12th at least one exhaust gas aftertreatment device 14th arranged, by means of which the exhaust gas can be post-treated. In the direction of flow of the exhaust tract 12th The exhaust gas flowing through is downstream of the exhaust gas aftertreatment device 14th no further exhaust gas aftertreatment device arranged for aftertreatment of the exhaust gas, so that the exhaust gas downstream of the exhaust gas aftertreatment device 14th has a state and in particular a composition in which or with which the exhaust gas from the exhaust tract 12th emanates and to an environment 16 of the motor vehicle flows.

The exhaust aftertreatment device 14th comprises, for example, at least one catalytic converter, by means of which the exhaust gas can be aftertreated. The motor vehicle also has a downstream of the exhaust gas aftertreatment device 14th arranged sensor device 18th on, by means of which in the method at least a portion of the exhaust gas downstream of the exhaust gas aftertreatment device 14th is measured. This is to be understood as meaning that the exhaust gas contains the component mentioned downstream of the exhaust gas aftertreatment device 14th has, so that the exhaust gas containing the component to the environment 16 flows without downstream of the exhaust gas aftertreatment device 14th to be further or again aftertreatment by means of an exhaust gas aftertreatment device of the motor vehicle. Furthermore, the motor vehicle has at least one or more components, the respective operation of which influences at least the component of the exhaust gas, that is to say it can be increased and / or decreased. A first of the components is, for example, the internal combustion engine 10 itself. A second of the components is, for example, the exhaust gas aftertreatment device 14th or their catalyst. A third of the components can, for example, be an injector shown particularly schematically in the figure 20th be by means of which, for example, a fuel, in particular a liquid fuel, in at least one combustion chamber of the internal combustion engine 10 can be introduced, in particular directly injected. A fourth of the components can, for example, be an air mass meter 22nd be, which can be designed, for example, as a hot-film air mass meter (HFM). Using the air mass meter 22nd For example, an air quantity or air mass flowing into the combustion chamber is determined, in particular measured. In addition, one with is particularly schematically shown in the figure 24 designated, further of the components designated.

Downstream of the internal combustion engine 10 and upstream of the exhaust aftertreatment device 14th is a sensor 26th arranged, by means of which, for example, at least one component of the exhaust gas upstream of the exhaust gas aftertreatment device 14th and downstream of the internal combustion engine 10 can be measured or determined. The sensor 26th is for example a nitrogen oxide sensor and can be one of the components.

The sensor device 18th can for example have a nitrogen oxide sensor and / or an HC sensor and / or a PM sensor and / or another sensor. By means of the nitrogen oxide sensor, for example, nitrogen oxides contained in the exhaust gas can be used as the aforementioned component of the exhaust gas downstream of the exhaust gas aftertreatment device 14th be measured. By means of the HC sensor, for example, unburned hydrocarbons contained in the exhaust gas can be used as the aforementioned component downstream of the exhaust gas aftertreatment device 14th be measured. By means of the PM sensor, for example, particles contained in the exhaust gas, in particular soot particles, can be used as the aforementioned component downstream of the exhaust gas aftertreatment device 14th are recorded.

In this case, the motor vehicle comprises an on-board measurement, which is shown particularly schematically in the figure and also referred to as on-board measurement (OBM), which is shown particularly schematically in the figure and denoted by 28. The OBM is an emission measurement which the sensor device 18th and uses its sensors to detect said component, also referred to as the end component, of the exhaust gas downstream of the exhaust gas aftertreatment device 14th to eat.

Furthermore, the motor vehicle has an on-board diagnosis, also referred to as on-board diagnostics (OBD) 30th which has, for example, respective sub-modules 32a-d. Using the on-board diagnosis 30th , in particular by means of the sub-modules 32a-d , the aforementioned components and thus, for example, the sensor designed as a nitrogen oxide sensor 26th , the air mass meter 22nd , the injector 20th and the other component 24 , especially on the basis of the respective OBD threshold values. Using the on-board diagnosis 30th For example, at least one actual operating value is determined for the respective component, which determines a current operation of the respective component, the operation of which can influence the end constituent of the exhaust gas. The actual operating value is compared, for example, with a setpoint operating value which characterizes a desired operation or a desired function of the respective component. If the actual operating value corresponds to the target operating value or if, for example, a difference between the actual operating value and the target operating value, in particular the mathematical amount of the difference, is less than the respective OBD threshold value, the respective component is assessed as functional or error-free, classified or assessed. If, however, the difference or its mathematical amount exceeds the OBD threshold value, then, for example, the respective component with respect to which the difference exceeds the OBD threshold value is assessed as faulty. In this case, for example, in particular by means of a module 34 the OBD, an error entry, in particular in a memory device of an electronic computing device that carries out the OBD, and a so-called engine control lamp (MIL) is activated in the interior of the motor vehicle, for example. This makes the driver of the motor vehicle aware that at least one of the components is faulty and that the driver should arrange for the motor vehicle to be serviced or repaired.

In order to ensure a particularly low-emission operation of the motor vehicle and to be able to avoid unnecessarily early maintenance or repairs of the motor vehicle, if the end component exceeds a first threshold value, the respective OBD threshold value, also referred to as the second threshold value, is used on the basis of which the components are determined by means of the An -Board diagnosis 30th monitored, tightened. The on-board diagnosis 30th is also known as on-board surveillance. The feature that the second threshold value (OBD threshold value) is tightened is to be understood in particular to mean that the OBD threshold value is reduced. If, for example, a first maximum deviation of the actual operating value from the target operating value is initially permitted without the corresponding component being classified as faulty, then by tightening the OBD threshold value, a second deviation smaller than the first deviation is permitted as a maximum, without this the corresponding component is classified as defective. This can For example, the motor vehicle or its operation can be changed or adjusted in such a way that the end component decreases again without the motor vehicle having to be serviced or repaired. As a result, a particularly low-emission operation of the motor vehicle can be implemented in a particularly advantageous manner.

List of reference symbols

10

Internal combustion engine

12th

Exhaust tract

14th

Exhaust aftertreatment device

16

Surroundings

18th

Sensor device

20th

Injector

22nd

Air mass meter

24

component

26th

sensor

28

On-board measurement

30th

On-board diagnosis

32a-d

Sub-modules

34

module

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was 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.

Patent literature cited

• DE 102004006992 A1 [0002]

Claims (4)

Method for operating a motor vehicle having an internal combustion engine (10), an exhaust gas tract (12) through which exhaust gas from the internal combustion engine (10) can flow and an exhaust gas aftertreatment device (14) arranged in the exhaust gas tract (12) for aftertreating the exhaust gas, in which a sensor device (18 ) of the motor vehicle, at least one component of the exhaust gas is measured downstream of the exhaust gas aftertreatment device (14), the motor vehicle also having at least one component (20, 22, 24, 26), through whose operation at least the component can be influenced, characterized in that when the Component exceeds a first threshold value, at least a second threshold value, on the basis of which the component (20, 22, 24, 26) is monitored by means of on-board monitoring (30) of the motor vehicle, is tightened. Procedure according to Claim 1 , characterized in that nitrogen oxides and / or unburned hydrocarbons and / or particles are measured as the constituent. Procedure according to Claim 1 or 2 , characterized in that as the component (20, 22, 24, 26) at least one injector (20) by means of which a fuel can be introduced into at least one combustion chamber of the internal combustion engine (10) and / or an exhaust gas recirculation device and / or at least one air mass meter (22) is used. Method according to one of the preceding claims, characterized in that at least part of the exhaust gas aftertreatment device (14) is used as the component (20, 22, 24, 26).

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