DE102013201867A1 - Method for operating combustion engine fit with e.g. on-board diagnostic system, involves determining current operating parameters and influencing factors for emissions of internal combustion engine and/or exhaust system - Google Patents

Abstract

The method involves determining monitoring functions of a combustion engine (12) and/or an exhaust system (10). Function of diesel oxidation catalyst (28), diesel particulate filter (30) and a feed device (31) of the internal combustion engine is monitored. Parameters and properties of nominal value of a data-based emissions model of the internal combustion engine and/or the exhaust system are determined by deviation of the monitoring functions. Current operating parameters and influencing factors are determined for emissions of the internal combustion engine and/or the exhaust system. Independent claims are also included for the following: (1) a control and/or regulating device for a motor car (2) a computer program comprising a set of instructions for performing a method for operating a combustion engine (3) a memory medium for a control and/or regulating device for a motor car.

Description

State of the art

The invention relates to a method for operating an internal combustion engine of a motor vehicle, a control and / or regulating device and a computer program according to the independent claims. This method can be used in an on-board diagnostic system (OBD system) of the internal combustion engine.

Internal combustion engines used in passenger cars and commercial vehicles are subject to regulations regarding permissible emissions in almost all countries of the world (in particular, particles, nitrogen oxides, hydrocarbons).

In addition, emissions must be monitored in real time during operation of the motor vehicle. A fault of a component of the internal combustion engine or the exhaust system, which leads to exceeding the emission limit values, must be detected and displayed to the driver of the vehicle. In addition, such an error must be stored in many cases in a non-volatile memory of the control and / or regulating device of the internal combustion engine.

To be able to monitor these requirements for all components of the internal combustion engine or the exhaust system and all pollutants of the exhaust gases in real time, nowadays a plurality of individual monitoring functions are used, which each serve to monitor a single component or functionality of the internal combustion engine or the exhaust system. In this case, properties and parameters, generally physical quantities, of the monitored component are determined directly or indirectly. In particular, it is monitored whether the property or the parameter of the monitored component deviates from the desired nominal state, which may be caused for example by a defect or by aging. The nominal value of a parameter of the internal combustion engine is the value that would be set if all components, actuators and sensors of the internal combustion engine would work in an ideal manner. In particular, if no component deviates from the design function due to component scattering, drift or a defect.

From the desired injection quantity requested by the control unit and the air mass measured by the air mass meter, for example, a nominal lambda of 1.7 would result at a certain operating point. If the lambda value measured by the lambda probe deviates from this nominal value, this may be caused by a drift of the injector, which injects more or less fuel than requested by the control unit.

A system in which all built-in subcomponents show minimal or no drifts or deviations from the nominal value is referred to below as the nominal system.

Based on the deviations or parameters from the nominal value determined during operation, it must then be determined whether the permissible emission limit values can no longer be met so that an OBD-relevant error must be reported in the system.

For example, there is a monitoring function which determines the deviation between the theoretically modeled lambda and the lambda value measured with the aid of a lambda sensor of the exhaust system. If the deviation is too large, it is assumed that the system has a defect and the required emission limit values can no longer be met.

In general, for each monitoring function for different motor vehicles or for different internal combustion engines, it must be experimentally determined from which value of the deviation the valid limit values of the emissions in the test procedure prescribed by the legislature are exceeded. A disadvantage of this approach is that it is extremely complex due to the large number of components that must be monitored, the complexity of a motor vehicle and the mutual interactions of various components of the internal combustion engine and the exhaust system and the drift of these components over the life of the motor vehicle, to separately determine these monitoring functions for each vehicle type and each engine, to re-condition the partially required characteristic curves and maps and to generate an OBD system in accordance with the legal requirements.

In connection with the invention, the components and influencing variables of an internal combustion engine and an exhaust system, which influence the emission behavior, are subdivided into several groups.

There are emission-relevant components, such as the injectors of an internal combustion engine or a catalyst and a particulate filter of the exhaust system. If these emission-relevant components no longer work as intended due to aging, drift or malfunction, this has a negative effect on the emission behavior of the internal combustion engine or the exhaust system.

Furthermore, there are monitoring functions, each of which using the existing sensors, such as a lambda probe, temperature sensors and other more, individual characteristics that characterize the effectiveness and / or the state of the components to be monitored determine.

In addition, there are so-called operating and environmental variables of the internal combustion engine, which are also important for the method according to the invention. Exemplary of such operating variables are the speed of the internal combustion engine, the injected fuel quantity and the cooling water temperature. Ambient variables are, for example, the vehicle speed and the ambient temperature

These operating variables and ambient variables likewise influence the emission behavior of the internal combustion engine and must therefore be known in order to be able to model the emissions of the internal combustion engine or the exhaust system and / or to assess whether the emissions of the internal combustion engine are higher than permitted due to a defective component.

In order to facilitate the understanding of the method according to the invention, not all emission-relevant components, monitoring functions, operating variables or other parameters are mentioned in the description of the invention. As an example for the modeling of the dynamic soot emissions of an internal combustion engine is on DE 10 2008 004 218 A1 directed.

In the DE 10 2009 055 058 A1 For example, a method for determining the NOx raw emissions of an internal combustion engine will be described.

Disclosure of the invention

In the method according to the invention for operating an internal combustion engine with an exhaust system in the monitoring functions of the motor vehicle and / or the internal combustion engine and / or the exhaust system determining properties or parameters of emission-relevant components, the invention provides that a data-based emission model of the internal combustion engine and / or the exhaust system is deposited, and that the emission model from the deviations of the parameters determined by the monitoring functions of their nominal values and the current operating variables determines the emissions of the internal combustion engine and / or the exhaust system.

The inventive method is based on a data-based emission model, being understood in the context of the invention as a data-based emission model, a model that has been determined by test bench tests of the motor vehicle or the internal combustion engine and / or the exhaust system. In this case, the operating variables of the motor vehicle or of the internal combustion engine and / or the exhaust system, which influence the emissions, specifically varied in the test bench and the resulting emissions of the exhaust system determined. In addition, the relationship between the drift of the emission-relevant components and the emissions is determined by measurements or by offline simulations of individual components of the internal combustion engine or the exhaust system.

By incorporating the characteristics and parameters determined by existing monitoring functions, which characterize drifts and system aging, an emission model can be formed which can calculate not only the emission values of the internal combustion engine when new but also, in particular, at any later time during operation of the internal combustion engine.

With the aid of the data-based emission model, one or more parameters can be determined during operation of the internal combustion engine in real time, based on the operating variables and environmental variables available in the vehicle and the data provided by the monitoring functions, which characterize the emissions of the internal combustion engine. This can be, for example, the instantaneous emission rate of one or more exhaust gas components, the expected total emission during a normalized test cycle or even the binary information as to whether the statutory emission limit values for at least one exhaust gas component are currently exceeded.

According to the invention, the OBD system then uses the parameters determined by the emission model, which characterize the vehicle emissions, in order to decide whether the statutory emission limits are violated and thus an OBD-relevant system error exists, in order to carry out the legally prescribed fault reactions in this case.

Important in connection with the claimed invention is that in the data-based emission model according to the invention the physical relationships between the influencing factors and the emissions of the motor vehicle need not be explicitly mapped. Therefore, no physical model of the internal combustion engine and its periphery is required. In some ways, the motor vehicle is considered in the creation of the emission model according to the invention as a "black box" whose emission behavior by changing the main influencing factors is examined without knowing in detail the physical and chemical and other connections inside the "black-box".

By using a data-based emission model according to the invention in conjunction with an on-board diagnostic system, it is possible to determine the emissions of a motor vehicle or its internal combustion engine in real-time, so that not for each emission-relevant component and each monitoring device a separate monitoring function in the control unit must be implemented. Therefore, with the aid of the method according to the invention, an improved OBD can be provided. At the same time, the expense of creating the emission model compared to the calibration of a plurality of different monitoring functions of a motor vehicle is significantly reduced. This makes it possible, even with a large variety of variants for each vehicle and each engine to create a sufficiently accurate emission model cost.

The operation of such a data-based emission model requires an increased computing power in the control and / or regulating device in comparison to the conventional models. Since the processor performance is cheaper from year to year and the variety of variants available on the market vehicles increases sharply, it is possible by the inventive method to have very good emission models and OBD systems based on it even with a variety of vehicle variants available. In addition, the effort of the motor vehicle manufacturer in the implementation of emission models and based OBD systems of motor vehicles is significantly reduced.

In an embodiment of the method according to the invention, it is provided that the emission model determines the total emissions expected in the legal driving cycle. The OBD system then compares the emissions predicted by the emissions model with the legal requirements and thus determines whether there is a violation of the law.

In an alternative embodiment of the invention, it is provided that the data-based emission model directly determines whether there is at least one collision with legal requirements, and makes this known to the on-board diagnostic system. In this embodiment, it is checked directly whether there is a collision with a legal requirement, without first calculating the emissions and then comparing them with the legal requirements.

If the emission model does not calculate absolute emissions, but only forecasts compliance with legal requirements, the complexity of the emission model is significantly reduced. As a result, the cost of creating the data-based emission model according to the invention is lower and the required computing power in the control and / or control device is reduced.

In a further alternative embodiment of the invention, it is provided that the emission model determines the instantaneous emission rate for one or more exhaust gas components. Depending on the legal requirements, it is provided according to the invention that the OBD system directly compares these instantaneous values with the legal requirements and / or averages the emissions over a time interval or a driving distance of the motor vehicle in order to check compliance with the legal limit values.

The method according to the invention provides that the emission model takes into account at least the drifts of the emission-relevant components and / or the monitoring device of the internal combustion engine and / or exhaust system. This makes it possible to detect over the entire life of the internal combustion engine, whether individual components or monitoring functions are approaching the end of their life and / or dysfunctional. This can then be signaled to the driver of the vehicle in a corresponding error message even before a violation of statutory provisions occurs and at the next inspection, this component can then be replaced.

It has proven to be advantageous if the emission model is a so-called ASC model (Advanced Simulation for Calibration) of the motor vehicle or the internal combustion engine and its exhaust system.

Furthermore, it has proved to be advantageous if the emission model is created by means of statistical experimental design, also referred to as Design of Experiments (DoE). The system behavior of the vehicle, the internal combustion engine and the exhaust system is examined in terms of emissions by the most important internal and external parameters and operating points of the motor vehicle varies and the resulting emissions are determined. As a result, the data-based emission model according to the invention can also be realized for a large number of vehicle variants and engine versions with a justifiable expense.

In a further advantageous embodiment of the invention, it is provided that the above-mentioned variables are changed in such a way that they characterize a specific error pattern of the motor vehicle and / or the internal combustion engine and / or the exhaust system.

In a further advantageous embodiment of the method according to the invention, the data-based emission model is supplemented by a physical emission model. In this case, it is provided that the physical emission model calculates the emissions of the internal combustion engine taking into account the operating and environmental variables on the assumption that the emission-relevant components of the internal combustion engine operate nominally, ie. H. have no drift. Furthermore, it is provided that the data-based emission model determines the difference of the emissions of the internal combustion engine to that of a nominal system, taking into account the parameters of the emission-relevant components determined by the monitoring functions, of their nominal value. In this case, the sum of the emissions from the physical model and the emission model according to the invention can then be used to monitor the emission values. Alternatively, the deviation can also be used directly as a monitoring criterion.

The advantages mentioned can also be realized with a control and / or regulating device and a computer program according to the independent claims. It has proved to be particularly advantageous if the control and / or regulating device comprises a separate arithmetic unit for carrying out the method according to the invention during operation of the internal combustion engine. For then the data-based emission model can work independently of the actual control and regulation functions.

Further advantages and advantageous embodiments of the invention are the drawing, the description and the claims removed. All features described in the drawing, the description and the claims can, without the need for further explanation, be essential to the invention individually or in any desired combination.

Show it:

1 : A schematic representation of an internal combustion engine and an exhaust system 10 a motor vehicle,

2 a first embodiment of an OBD system according to the invention and

3 a second embodiment of an OBD system according to the invention and

4 : A third embodiment of an OBD system according to the invention.

The 1 represents a simplified system consisting of the exhaust system 10 and the internal combustion engine 12 to illustrate the invention with this system.

From the internal combustion engine 12 flows through a pipe connection 14 Exhaust gas in the exhaust system 10 , A control and / or regulating device 16 is about incoming and outgoing electrical wiring 20 and 22 with the internal combustion engine 12 as well as incoming and outgoing electrical lines 24 and 26 with components of the exhaust system 10 connected. The compounds are merely indicated in the drawing. Furthermore, the control and / or regulating device comprises 16 a computer program 18 and an on-board diagnostic system according to the invention 21 , The computer program 18 can with the on board diagnostic system 21 Exchange data.

In the exhaust system 10 the exhaust gas is passed through substantially from left to right and prepared. In the present case, it is the exhaust system 10 a diesel motor vehicle, the invention is not limited to diesel engines, but can also be used in gasoline engines. The exhaust system 10 has a diesel oxidation catalyst in the flow direction of the exhaust gas 28 , a diesel particulate filter 30 , a feeder 31 for an aqueous urea solution 33 and an SCR catalyst 32 on (SCR means "selective catalytic reduction").

Upstream of the diesel oxidation catalyst 28 is a lambda sensor 34 arranged in the exhaust stream. Upstream and downstream of the SCR catalyst 32 is ever a NOx sensor 36 arranged in the exhaust stream. Furthermore, the exhaust system 10 in the present case four temperature sensors 38 on. The temperature sensors 38 , the lambda sensor 34 and the NOx sensors 36 are with the control and / or regulating device 16 about the incoming and outgoing electrical wires 24 and 26 connected. This is in the drawing of 1 but not shown individually.

In the upper right area of the drawing of 1 is a storage tank 40 arranged, which is the aqueous urea solution 33 contains and via a hydraulic line 41 with the feeder 31 connected is.

Left next to the storage tank 40 is a measuring device 42 represented which physical Quantities of the aqueous urea solution 33 can determine. The measuring device 42 is with the control and / or regulating device 16 via electrical lines 44 and 46 electrically connected. A temperature sensor 47 determines the temperature of the aqueous urea solution 33 in the storage container 40 ,

The emission behavior of the internal combustion engine 12 or the exhaust system 10 depends inter alia on operating variables of the internal combustion engine. Such operating _variables can be, for example, the rotational speed n, the injected fuel quantity Q _inj and the operating temperature T _{bkm of} the internal combustion engine. In addition, the emission behavior is influenced by other factors, such as the ambient temperature T _amb , or a speed v of the vehicle. Of course, this list is not exhaustive, but merely by way of example. These quantities are detected using suitable sensors or, if necessary, calculated.

Functionally relevant components of the motor vehicle which influence the emission behavior are, for example, the fuel metering system (not shown in detail) and the air system, the diesel oxidation catalytic converter 28 , the diesel particulate filter 30 , the feeder 31 and the SCR catalyst 32 , A drift or a malfunction of one of these emission-relevant components leads to a deterioration of the emission values of the internal combustion engine or the exhaust system.

To the function of the emission-relevant components and the emissions of the internal combustion engine 12 or the exhaust system 10 during the entire life of the internal combustion engine 12 to be able to monitor are in the engine control unit 16 implemented several monitoring functions, which, for example, the sensor signals of a lambda probe 34 , the NOx sensor 36 , the temperature sensors 38 and 47 use in order to determine properties or parameters of the internal combustion engine in general and the emission-related components in particular.

In the 2 a first embodiment of an OBD system according to the invention is shown as a block diagram.

With the reference number 48 a block is described in which all operating variables are summarized. The operating variables include, for example, the current rotational speed n, the injected fuel quantity Q, the cooling water temperature of the internal combustion engine and others. These operating variables go into the data-based emission model according to the invention 61 as an input.

With the reference number 50 is a block referred to, in which all other factors, such as the ambient temperature T _amb and the speed v of the motor vehicle, are summarized. They also go into the data-based emission model according to the invention 61 as an input.

The distinction between farm sizes and external parameters or other factors is not mandatory; they can also be summarized in a block.

In the function blocks 52 to 56 are the various monitoring functions of the internal combustion engine 12 or the exhaust system 10 summarized. For example, in the block 52 a monitoring function based on the lambda probe 34 in the block 54 a monitoring function based on the NOx sensor and in the block 56 a monitoring function, which signals the temperature sensors 38 respectively 47 used to be summarized.

This list of blocks 50 to 56 is not exhaustive, but merely exemplary. If necessary, the output values of various further monitoring functions can also be included in the emission model according to the invention 61 Find.

Based on these input variables, which are only given by way of example, the emission model is determined 61 Emission values of the different pollutants. By way of example, the particles PM, the nitrogen oxides NOx, the hydrocarbons HC and the carbon monoxide CO are listed here. Again, this is not an exhaustive list.

The way of the emission model 61 determined emissions are the input variables of a downstream evaluation logic and error handling unit 58 (hereinafter referred to as error handling unit 58 in the error handling unit 58 It is checked whether one or more emissions are above a legally prescribed limit. These may be instantaneous values or emission values integrated over a time or a route and / or averaged.

In the error handling unit 58 If necessary, an error handling takes place. This can be, for example, the activation of a warning light in the dashboard of the motor vehicle or the storage of an error message in the non-volatile part of the control and / or regulating device 16 be. The error handling is in 2 as an arrow 59 indicated.

The error handling unit 58 is the same as the emission model 61 Part of the OBD system 21 ,

3 shows an alternative embodiment. In this alternative embodiment, the emission model is 61 designed to directly determine whether or not there is a breach of a legal requirement with regard to emissions. If necessary, a warning lamp is activated on the dashboard and / or a corresponding message is stored in the control unit. So the result is in a sense binary.

Because this embodiment without the "detour" on the determination of emissions and the subsequent comparison with the statutory requirements, its creation is easier and it will be less computing power in the control and / or control unit 16 needed.

4 shows another alternative approach. In this alternative approach, the operating characteristics of the block become 48 a physical model 60 which calculates the so-called nominal emissions on the basis of a physical model.

The initial values of the monitoring functions 52 to 56 find their way into the physical model 60 and the emission model referred to below as the delta emission model 62 , In the delta emission model 62 only differences to the nominal emissions of the physical model 60 determined and the evaluation logic and error handling unit 58 fed. If the differences are from the delta emission model 62 If the values determined exceed specified limits, then this is done in the evaluation logic and error handling 58 detected and carried out an appropriate error handling.

In the 2 to 4 are various embodiments of on-board diagnostic systems according to the invention 21 shown. They comprise a data-based emission model 61 , respectively. 62 ,

If these on-board diagnostic systems 21 in a control and / or regulating device 16 is implemented, it is possible with the aid of the emission model according to the invention 61 . 62 the emission impact of the identified malfunctions or drifts of the emission-relevant components 28 . 30 . 31 and 32 to calculate. As a result, the rating may be in the error handling unit 58 whether there is an OBD-relevant error and thus a warning message must be issued or another legally required error response must be performed, made directly on the basis of the comparison with the legal limits for the emission. In a conventional OBD system, however, the error thresholds are determined purely empirically. Therefore, in a conventional OBD system, there is a greater risk that a system will be misdiagnosed as a defect even though the statutory emission limit values are not yet exceeded or a system is wrongly diagnosed as OK, although the statutory emission limit values have already been exceeded are.

At the same time, the creation of the OBD system is greatly simplified because the data-based emission model according to the invention 61 does not have to map the physical relationships, for example between the injection quantity and the particle emissions, taking into account the drift of individual components or malfunctions of individual components.

Because the inventive creation of the emission model 61 . 62 with the help of statistical methods at least partially automated and the emission model created in this way 61 Subsequently, it is only necessary to check its stability and image quality. Therefore, the human and financial expenses involved in creating such a model are much lower than with a conventional OBD system.

In a conventional OBD system, characteristic curves or characteristic diagrams have to be recorded in separate tests for a large number of components and, at least in part, the physical relationships must be modeled. In order to exclude interactions with other monitoring functions as far as possible, this "isolated" approach according to the state of the art often requires a very elaborate and precise modeling, which further increases the effort.

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 102008004218 A1 [0015]
• DE 102009055058 A1 [0016]

Claims (15)

Method for operating an internal combustion engine ( 12 ) with an exhaust system ( 10 ), using by monitoring functions ( 52 . 54 . 56 ) of the motor vehicle and / or the internal combustion engine ( 12 ) and / or the exhaust system ( 10 ) determined exhaust gas-relevant parameters and properties of the internal combustion engine ( 12 ) and / or the exhaust system ( 10 ) the function of emission-relevant components ( 28 . 30 . 31 ) of the internal combustion engine ( 12 ) and / or the exhaust system ( 10 ), characterized in that a data-based emission model ( 61 . 62 ) of the internal combustion engine ( 12 ) and / or the exhaust system ( 10 ) from the deviations of the monitoring functions ( 52 . 54 . 56 ) determined parameters and properties of their nominal values, the current operating _variables (n _BKM , Q _inj , T _BKM ) and / or other influencing variables (T _Amb ) characteristics determined that the emissions of the internal combustion engine ( 12 ) and / or the exhaust system ( 10 ) characterize. Method according to claim 1, characterized in that the emission model ( 61 . 62 ) determines the emissions to be expected in the legal driving cycle and that of the emission model ( 61 ) compares emissions with a specified threshold, which is derived from legal requirements and determines whether at least one collision with legal requirements exists Method according to claim 1 or 2, characterized in that the emission model ( 61 . 62 ) used to issue a warning if necessary and / or possibly perform further legally prescribed error responses. Method according to one of the preceding claims, characterized in that the emission model ( 61 . 62 ) directly determines whether there is at least one collision with legal requirements and then optionally issues a warning message and / or possibly performs further legally prescribed error responses. Method according to one of the preceding claims, characterized in that the emission model ( 61 . 62 ) at least the drift of the emission-relevant components ( 28 . 30 . 31 ) and / or the monitoring functions ( 52 . 54 . 56 ) of the internal combustion engine ( 12 ) and / or the exhaust system ( 10 ) considered. Method according to one of the preceding claims, characterized in that the emission model ( 61 . 62 ) is a data-based model. Method according to one of the preceding claims, characterized in that the emission model and using statistical methods and / or methods of DoE (design of experiment) is created. Method according to one of the preceding claims, characterized in that the creation of the emission model ( 61 . 62 ) using operating _variables (n _BKM , Q _inj , T _BKM ) and / or other influencing _variables (T _Amb ) of the motor vehicle and / or the internal combustion engine ( 12 ) and / or the exhaust system ( 10 ) and taking into account the deviations of the monitoring functions ( 52 . 54 . 56 ) of the motor vehicle and / or the internal combustion engine ( 12 ) and / or the exhaust system ( 10 ) determined exhaust-related parameters and properties of their nominal value. Method according to Claim 8, characterized in that the variables are changed in such a way that they produce a specific error pattern of the motor vehicle and / or of the internal combustion engine ( 12 ) and / or the exhaust system ( 10 ) characterize. Method according to at least one of the preceding claims, characterized in that the creation of the emission model ( 61 . 62 ), taking into account that of the monitoring functions ( 52 . 54 . 56 ) determined variables takes place. Method according to at least one of the preceding claims, characterized in that the data-based emission model ( 62 ) the difference to a physical emission model ( 60 ) of the internal combustion engine ( 12 ) and / or the exhaust system ( 10 ) and that the physical model ( 60 ) describes a composition of the exhaust gas in a nominal system as a function of physical quantities. Control and / or regulating device ( 16 ) for a motor vehicle, characterized in that it comprises an on-board diagnostic system operating according to a method of claims 1 to 11 ( 21 ) with an emission model ( 61 . 62 ). Control and / or regulating device ( 16 ) according to claim 12, characterized in that it has a separate computing unit for carrying out the method according to one of claims 1 to 11 during operation of the internal combustion engine ( 12 ). Computer program characterized in that it is programmed to perform a method according to any one of claims 1 to 11. Storage medium for a control and / or regulating device for a motor vehicle, characterized in that it is an on-board diagnostic system operating according to a method of claims 1 to 11 ( 21 ) with an emission model ( 61 . 62 ).

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