Method for operating a drive unit for a motor vehicle, corresponding drive unit and computer program product

Abstract

The invention relates to a method for operating a drive unit (2) for a motor vehicle (1), which has an exhaust gas-generating drive unit and an exhaust gas aftertreatment device, wherein, during operation of the drive unit (2), a quantity of exhaust gas components is accumulated and a distance traveled by the motor vehicle (1) is recorded. It is provided that, in addition to the distance traveled, an actual value of a classification parameter is determined during operation of the drive unit (2), and based on this actual value, a threshold value data set containing a threshold is selected from several threshold value data sets. If the threshold value contained in the selected threshold value data set is exceeded by the quantity of exhaust gas components related to the distance traveled, a fault in the drive unit (2) is detected.The invention further relates to a drive device (2) for a motor vehicle (1) and a computer program product.

Description

[0001] The invention relates to a method for operating a drive unit for a motor vehicle, which has an exhaust gas-generating drive unit and an exhaust gas aftertreatment device, wherein during operation of the drive unit a quantity of exhaust gas components is accumulated and a distance traveled by the motor vehicle is recorded, wherein in addition to the distance traveled during operation of the drive unit an actual value of a classification parameter is determined and, based on the actual value, a threshold value data set containing a threshold is selected from several threshold value data sets, in particular at the end of operation of the drive unit, wherein if the threshold value contained in the selected threshold value data set is exceeded by the quantity of exhaust gas components related to the distance traveled, a fault of the drive unit is detected.wherein an environmental parameter describing the environment of the motor vehicle is used as the classification parameter. The invention further relates to a drive unit for a motor vehicle and a computer program product.

[0002] For example, the prior art includes German patent application DE 10 2009 000 286 A1. This describes a method for diagnosing a particulate filter for filtering particles from the exhaust gas of an internal combustion engine, wherein a particle sensor collecting particles is arranged in the direction of exhaust gas flow downstream of the particulate filter, and wherein a measure of the particle sensor's loading is determined from an output signal of the particle sensor.The system provides that during a measurement cycle, the time integral of a parameter correcting for the particle emission of the internal combustion engine is formed, that at at least one measurement point during the measurement cycle the measure for the loading of the particle sensor is assigned to the integral, and that a defective particle filter is concluded if the measure for the loading of the particle sensor is higher than a loading threshold assigned to the integral or if the integral is lower than an integral threshold assigned to the measure for the loading of the particle sensor.

[0003] The German patent application DE 10 2022 201 822 A1 relates to a method for evaluating emission values ​​of an internal combustion engine, comprising measuring an emission value for at least one exhaust gas component in the exhaust gas of an internal combustion engine; recording one or more additional operating parameters present during the measurement of the emission value; deriving an emission value normalized to a reference value from the measured emission value; classifying the normalized emission value into one or more classes based on the recorded additional operating parameters; checking whether the normalized emission value meets one or more predefined conditions, the one or more conditions being determined depending on the one or more classes; and triggering a predefined reaction depending on the result of the test.

[0004] The object of the invention is to propose a method for operating a drive unit for a motor vehicle which has advantages over known methods, in particular reliably informing a user of the motor vehicle about a fault in the drive unit which causes increased exhaust emissions.

[0005] According to the invention, this is achieved by a method for operating a drive unit for a motor vehicle with the features of claim 1. It is provided that different comparison values ​​for the classification parameter are stored in the threshold data sets, wherein, for selecting the threshold data set, a correlation value is determined for each of the threshold data sets between the comparison value stored therein and the determined actual value of the classification parameter, and the threshold data set with the correlation value indicating the highest agreement is selected, wherein the threshold data set is only selected if the correlation value lies within a range of values ​​indicating an agreement between the comparison value and the determined actual value of the classification parameter.

[0006] Advantageous embodiments with expedient further developments of the invention are specified in the dependent claims. It should be noted that the exemplary embodiments described in the description are not limiting; rather, any variations of the features disclosed in the description, the claims, and the figures are possible.

[0007] The method is designed for operating the drive system. It is preferably implemented or carried out by means of a control unit for the drive system. The drive system or its control unit is preferably an integral part of the motor vehicle, but can of course also be separate from it, particularly until the drive system or the control unit is mounted on or in the motor vehicle. The drive system serves to propel the motor vehicle, i.e., to provide a drive torque directed towards propelling the motor vehicle. To provide the drive torque, the drive system includes the drive unit. The drive unit is preferably an internal combustion engine, in particular a gasoline engine or a diesel engine.

[0008] During operation, the drive unit is supplied with fuel and fresh gas at least intermittently, with the fresh gas containing fresh air at least intermittently. Additionally, the fresh gas may contain exhaust gas if exhaust gas recirculation is implemented, in which the exhaust gas generated by the drive unit is at least partially returned to the drive unit as a component of the fresh gas. The fuel and fresh gas supplied to the drive unit form a fuel-fresh gas mixture with a specific composition, which is then reacted within the drive unit.

[0009] During operation of the engine, exhaust gas is produced due to the chemical reaction of fuel and fresh air. This exhaust gas is discharged towards the outside environment of the engine or vehicle. Since the exhaust gas generated by the engine contains pollutants, it is first routed to an exhaust aftertreatment system before being released into the environment. In the exhaust aftertreatment system, the pollutants are at least partially converted into less harmful products. Only after passing through the exhaust aftertreatment system is the exhaust gas discharged into the environment, primarily through an exhaust pipe on the engine.

[0010] The exhaust aftertreatment system preferably includes at least one vehicle catalyst, in particular a three-way catalyst, an oxidation catalyst, or an NOₓ catalyst. x- a storage catalyst or an SCR catalyst. The vehicle catalyst may be integrated into a particulate filter, particularly a gasoline particulate filter or a diesel particulate filter. For this purpose, the particulate filter is, for example, provided with a catalytic coating. The conversion rate, and thus the conversion efficiency of the exhaust aftertreatment system, which converts the pollutants into less harmful products, depends in particular on the composition of the exhaust gas supplied to the exhaust aftertreatment system or the vehicle catalyst, as well as on the temperature of the exhaust aftertreatment system.

[0011] The components of the exhaust gas produced by the engine are also referred to as raw emissions. Raw emissions describe the composition of the exhaust gas upstream of the exhaust aftertreatment system, or in terms of flow characteristics, between the engine and the exhaust aftertreatment system. As the exhaust gas passes through the aftertreatment system, some of the substances contained within it are transformed, thus changing its composition. The substances present in the exhaust gas downstream of the aftertreatment system, which constitute the exhaust gas, are also referred to as tailpipe emissions, since this is the composition of the exhaust gas released into the environment through the engine's tailpipe.

[0012] As mentioned, the amount of pollutants contained in the tailpipe emissions depends on the raw emissions, but also on the conversion efficiency of the exhaust aftertreatment system or the vehicle's catalytic converter. This efficiency is temperature-dependent. Specifically, the conversion efficiency decreases the greater the temperature of the exhaust aftertreatment system or the vehicle's catalytic converter deviates from its operating temperature; in other words, the greater the absolute difference between the temperatures. The temperature of the exhaust aftertreatment system or the vehicle's catalytic converter refers, for example, to the temperature of a ceramic honeycomb structure coated with the catalytic material.

[0013] According to the invention, the exhaust emissions of the drive unit are continuously monitored during its operation. For this purpose, the quantity of exhaust components is recorded cumulatively, i.e., summed or integrated during the operation of the drive unit. The operation of the drive unit extends from the start of operation to the end of operation. The start of operation is characterized in particular by the fact that the drive unit is started or at least prepared for starting.

[0014] Starting the drive unit means, for example, increasing its rotational speed from a standstill (zero speed) towards idle speed, particularly down to idle speed. Preparing for starting includes, for example, activating the ignition of the drive unit. The end of operation is preferably characterized by stopping the drive unit, i.e., reducing its rotational speed to zero. However, it can also be provided that the end of operation only occurs once the ignition of the drive unit is switched off.

[0015] During operation of the drive unit, the quantity of at least one exhaust component released into the external environment, i.e., the exhaust component quantity, is measured. The exhaust component quantity describes the amount of the exhaust component contained in the tailpipe emissions. The quantity of the exhaust component occurring per unit of time is determined, for example, from its proportion in the exhaust gas and the exhaust flow rate. The exhaust flow rate describes the quantity of exhaust gas emitted into the external environment per unit of time. The exhaust flow rate is, for example, a volumetric flow rate, but preferably a mass flow rate.

[0016] The exhaust component quantity is cumulative, so that the total amount of exhaust component released into the external environment during the operation of the propulsion system is recorded. The exhaust component quantity is determined, for example, using an exhaust aftertreatment model that describes the conversion of the exhaust component contained in the raw emissions within the exhaust aftertreatment system.

[0017] The exhaust aftertreatment model simulates the conversion of a single exhaust component using the aftertreatment system. For example, the proportion of the exhaust component in the raw emissions upstream of the aftertreatment system is fed into the model. The model then outputs the proportion of the exhaust component in the exhaust gas downstream of the aftertreatment system. It is also possible, of course, to measure the quantity or proportion of the exhaust component, for example, using a suitable sensor.

[0018] For example, it is planned to record the quantity of exhaust gas components only for a single exhaust gas component, for example for nitrogen oxide (NOx). x), in particular nitrogen monoxide (NO) and / or nitrogen dioxide (NO2). However, it can also be provided that a separate quantity of exhaust gas components is measured for each of several components. In this case, several threshold values ​​are preferably provided, in particular a threshold value for each of the several exhaust gas component quantities.

[0019] In addition to the quantity of exhaust components, the distance traveled by the vehicle during operation of the propulsion system is determined. Based on the quantity of exhaust components and the distance traveled, a distance-related quantity of exhaust components is calculated by dividing the quantity of exhaust components by the distance traveled. The distance-related quantity of exhaust components describes the amount of the exhaust component emitted into the environment by the propulsion system per unit of distance traveled. For example, if the quantity of exhaust components is given in grams and the distance traveled in kilometers, the distance-related quantity of exhaust components is expressed in grams per kilometer.

[0020] For example, the amount of exhaust components emitted over a specific distance is compared to a threshold value. If the amount of exhaust components emitted over a specific distance exceeds the threshold, a fault in the drive system is detected. In this case, a warning message is displayed to the vehicle's user, indicating that the threshold has been exceeded. However, this approach has the disadvantage that, firstly, the amount of exhaust components depends on the user's driving profile and / or environmental conditions, and secondly, the threshold value is usually determined within a standardized measurement cycle. Therefore, it is possible for a fault in the drive system to be detected even though the amount of exhaust components emitted over a specific distance is far from a legally defined limit.

[0021] For this reason, in addition to the distance traveled, the actual value of the classification parameter is determined during the operation of the drive system. The classification parameter describes the operation of the drive system and / or the driving operation of the vehicle. Based on the actual value, the threshold data set is then selected from several threshold data sets. The threshold value is contained within the threshold data set, so that ultimately the threshold value is determined depending on the classification parameter or its actual value. This results in an adjustment of the threshold value depending on the operation of the drive system or the driving operation of the vehicle; the threshold value is therefore selected situationally.

[0022] If the distance-related exhaust component quantity exceeds the threshold value contained in the selected threshold data set, a fault in the drive system is detected, as previously explained. Ultimately, several threshold data sets are stored, for example, in the drive system's control unit, which were determined for different values ​​of the classification parameter, such as on a test bench. Each threshold data set contains a threshold value selected to match the actual value of the classification parameter.

[0023] Each of the threshold values ​​is, in particular, lower than the legally prescribed limit for the quantity of exhaust components per kilometer driven. For example, the threshold values ​​of the threshold data sets differ from one another. This approach ensures reliable detection of drive system faults, resulting in high user acceptance of the resulting warning message. The user is therefore only notified of the drive system fault when countermeasures are actually required, such as a repair.

[0024] A further development of the invention provides that at least one of the following parameters is used as a classification parameter: an operating parameter of the drive unit, a driving parameter describing the journey of the motor vehicle during operation of the drive unit, and an environmental parameter describing the environment of the motor vehicle. It is possible that only one of the aforementioned parameters is used as a classification parameter. However, it is particularly preferred that the classification parameter comprises several of the aforementioned parameters, in particular all of them. The operating parameter describes the operation of the drive unit, and the driving parameter describes the journey of the motor vehicle during operation of the drive unit. Finally, the environmental parameter describes the environment of the motor vehicle, for example, in the form of weather conditions or the like.In any case, it is possible to precisely select the threshold data set using one or more of the parameters mentioned.

[0025] A further development of the invention provides that the operating parameter is determined as a function of one of the following quantities and / or their respective time course: torque of the drive unit, speed of the drive unit, power of the drive unit and operating time of the drive unit, and / or that the driving parameter is determined as a function of one of the following quantities and / or their respective time course: speed of the motor vehicle, acceleration of the motor vehicle and driving time of the motor vehicle.

[0026] Both the operating parameter and the driving parameter can therefore be determined from one of the aforementioned quantities and / or their respective time course. The operating parameter and the quantities describing it relate to the drive system or drive unit, while the driving parameter and the quantities describing it relate to the vehicle's driving operation. Both the operating parameter and the driving parameter can be determined from just one of the aforementioned quantities, from several, or even all of them.

[0027] Torque describes the torque currently provided by the drive unit, and speed describes the current rotational speed of the drive unit. Similarly, power refers to the instantaneous power output of the drive unit. The operating time of the drive unit describes the duration for which the drive unit was operated to provide torque or drive torque during the operation of the drive system. Speed ​​and acceleration refer to the instantaneous speed and acceleration of the vehicle. The vehicle's travel time describes the period of time the vehicle was in motion during the operation of the drive system, specifically the time it maintained a non-zero speed. These parameters enable a targeted selection of the threshold data set.

[0028] A further development of the invention provides that a user parameter describing a user of the motor vehicle is used as the classification parameter. The user is understood to be, in particular, the driver of the motor vehicle; the user thus significantly influences the operation of the drive system. For this reason, user identification is to be carried out, and the user parameter describing the user is to be used as the classification parameter, preferably in addition to one of the parameters already mentioned. Of course, it is also possible for the user parameter alone to be used as the classification parameter. In any case, the advantages already mentioned are achieved.

[0029] The invention provides that different reference values ​​for the classification parameter are stored in the threshold data sets. The threshold data sets are thus provided for different values ​​of the classification parameter. Preferably, the threshold data sets differ consistently with respect to their reference values; that is, they do not contain identical reference values. This also serves to achieve the advantages already mentioned.

[0030] The invention provides that, to select the threshold data set, a correlation value is determined for each threshold data set between the reference value stored therein and the determined actual value of the classification parameter, and the threshold data set with the correlation value indicating the highest agreement is selected. The correlation value describes the agreement between the respective reference value and the actual value. For example, the correlation value is a difference between the reference value and the actual value, in particular the absolute value of such a difference. Ultimately, the threshold data set for which the determined correlation value indicates the highest agreement between the reference value and the actual value is selected. If the difference is used, for example, the threshold data set with the lowest correlation value is chosen.The described procedure enables efficient selection of the threshold data set that best describes the driving operation of the motor vehicle.

[0031] The invention provides that the threshold data set is selected only if the correlation value lies within a range indicating a match between the reference value and the determined actual value of the classification parameter. If the match between the reference value and the actual value is too low, the corresponding threshold data set is not selected, even if it contains the correlation value indicating the highest match. Ultimately, this means that if the correlation value for any of the threshold data sets does not lie within the range, no threshold data set is selected. In this case, the legally prescribed limit value is preferably used as the threshold. The range is preferably chosen such that the same threshold data set is selected for journeys of the motor vehicle carried out in a similar manner.Therefore, the threshold contained in the selected threshold data set is representative for the respective journey.

[0032] A further development of the invention provides that, if the correlation value lies outside the value range, an additional threshold data set is added to the threshold data sets. The threshold value stored in this additional threshold data set is determined from the quantity of exhaust gas components related to the distance traveled, and the stored comparison value of the classification parameter is set to the determined actual value of the classification parameter. Thus, if no suitable threshold data set exists for the actual value of the classification parameter, one is created and subsequently forms part of the threshold data sets.

[0033] The additional threshold data set stores the actual value of the classification parameter determined during operation of the drive unit, as well as the distance-related exhaust component quantity determined during operation. The distance-related exhaust component quantity is preferably limited to the legally prescribed limit value when values ​​increase; it must not exceed this limit. The described procedure ensures that the threshold data sets can be extended to accommodate new conditions.

[0034] The invention further relates to a drive unit for a motor vehicle, in particular for carrying out the method according to the description in this document, wherein the drive unit has an exhaust gas generating drive unit and an exhaust gas aftertreatment device, and wherein the drive unit is designed and configured to accumulate an amount of exhaust gas components during operation of the drive unit and to record a distance traveled by the motor vehicle.

[0035] The drive unit is also designed and configured to determine, in addition to the distance traveled during operation of the drive unit, an actual value of a classification parameter and, based on the actual value, to select a threshold data set containing a threshold value from several threshold data sets, particularly at the end of operation of the drive unit, whereby if the threshold value contained in the selected threshold data set is exceeded by the quantity of exhaust components related to the distance traveled, a fault of the drive unit is detected, wherein an environmental parameter describing an environment of the motor vehicle is used as the classification parameter.It is further provided that different comparison values ​​for the classification parameter are stored in the threshold data sets, whereby, to select the threshold data set, a correlation value is determined for each of the threshold data sets between the comparison value stored in it and the determined actual value of the classification parameter, and the threshold data set with the correlation value indicating the highest agreement is selected, whereby the threshold data set is only selected if the correlation value lies within a range of values ​​indicating an agreement between the comparison value and the determined actual value of the classification parameter.

[0036] The advantages of such a drive system design and such a procedure have already been mentioned. Both the drive system and the method for operating it may be further developed as explained in this description, and reference is made to those explanations.

[0037] Furthermore, the invention relates to a computer program product comprising commands that cause the drive device to execute the described method as described herein. For the advantages and possible advantageous embodiments, reference is made to the description in its entirety.

[0038] The features and combinations of features described in the description, in particular those described in the following figure description and / or shown in the figures, can be used not only in the combinations specified, but also in other combinations or individually, without departing from the scope of the invention, in particular the scope of the claims. Thus, embodiments that are not explicitly shown or explained in the description and / or the figures, but which emerge from or can be derived from the explained embodiments, particularly within the scope of the claims, are also to be considered as encompassed by the invention.

[0039] The invention is explained in more detail below with reference to the exemplary embodiments shown in the drawing, without limiting the invention. The only embodiment shown is... Fig. 1 A schematic representation of a motor vehicle with a drive unit which has an exhaust gas generating drive unit and an exhaust gas aftertreatment device.

[0040] The Fig. Figure 1 shows a schematic representation of a motor vehicle 1, which has a drive unit 2 that in turn has an exhaust-generating drive unit. The drive unit 2 also has an exhaust aftertreatment system (not shown) which is arranged fluid-wise between the drive unit and an exhaust pipe 3 of the motor vehicle. Exhaust gas generated by the drive unit is expelled into the external environment of the motor vehicle 1 via the exhaust pipe 3.

[0041] The drive unit 2 also has a control unit 4. With the help of the control unit 4, a quantity of an exhaust component is determined during operation of the drive unit 2, namely downstream of the exhaust aftertreatment device, i.e. in the area of ​​the tailpipe 3. The quantity of the exhaust component is accumulated during operation of the drive unit 2, in particular summed up or integrated, so that at the end of operation of the drive unit 2 a total quantity of the exhaust component is available that has been produced during operation.

[0042] Additionally, the distance traveled by the vehicle 1 during the operation of the drive unit 2 is recorded. A distance-specific amount of exhaust components is calculated from the cumulative amount of exhaust gas components and the distance traveled. This amount is compared to a threshold value, and if the distance-specific amount of exhaust gas components exceeds the threshold, a fault in the drive unit 2 is detected.

[0043] Since the quantity of exhaust components depends on the operation of the vehicle 1 or the operation of the drive unit 2, a classification parameter describing the operation of the drive unit 2 and / or the operation of the vehicle 1 is first determined; more precisely, an actual value of this classification parameter. Based on this actual value, a threshold value is selected from several threshold value data sets. This threshold value data set contains a threshold value that is ultimately used for comparison with the quantity of exhaust components measured over the distance traveled. This approach enables particularly precise fault detection. REFERENCE MARK LIST: 1 motor vehicle 2 Drive unit 3 tailpipe 4 Control unit

Claims

[1] Method for operating a drive unit (2) for a motor vehicle (1) which has an exhaust gas-generating drive unit and an exhaust gas aftertreatment device, wherein during operation of the drive unit (2) a quantity of exhaust gas components is accumulated and a distance traveled by the motor vehicle (1) is recorded, wherein in addition to the distance traveled during operation of the drive unit (2) an actual value of a classification parameter is determined and, based on the actual value, a threshold value data set containing a threshold is selected from several threshold value data sets, wherein if the threshold value contained in the selected threshold value data set is exceeded by the quantity of exhaust gas components related to the distance traveled, a fault of the drive unit (2) is detected, wherein an environmental parameter describing an environment of the motor vehicle (1) is used as the classification parameter, characterized by, that different comparison values ​​for the classification parameter are stored in the threshold data sets, wherein, to select the threshold data set, a correlation value is determined for each of the threshold data sets between the comparison value stored in it and the determined actual value of the classification parameter, and the threshold data set with the correlation value indicating the highest agreement is selected, wherein the threshold data set is only selected if the correlation value lies within a range of values ​​indicating an agreement between the comparison value and the determined actual value of the classification parameter. [2] Method according to claim 1, characterized by, that as a classification parameter one of the following parameters is additionally used: an operating parameter of the drive unit (2) and a driving parameter describing a journey of the motor vehicle (1) during the operation of the drive unit (2). [3] Method according to claim 2, characterized by , that the operating parameter is determined as a function of one of the following quantities and / or their respective time course: torque of the drive unit, speed of the drive unit, power of the drive unit and operating time of the drive unit, and / or that the driving parameter is determined as a function of one of the following quantities and / or their respective time course: speed of the motor vehicle (1), acceleration of the motor vehicle (1) and driving time of the motor vehicle (1). [4] Method according to any one of the preceding claims, characterized by, that a user parameter describing a user of the motor vehicle (1) is used as the classification parameter. [5] Method according to any one of the preceding claims, characterized by , that if the correlation value lies outside the range of values, an additional threshold data set is added to the threshold data sets, whereby the threshold value stored in the additional threshold data set is determined from the quantity of exhaust components related to the journey distance and the stored comparison value of the classification parameter is set equal to the determined actual value of the classification parameter. [6] Drive unit (2) for a motor vehicle, in particular for carrying out the method according to one or more of the preceding claims, wherein the drive unit (2) has an exhaust gas generating drive unit and an exhaust gas aftertreatment device, and wherein the drive unit (2) is provided and configured to accumulate an amount of exhaust gas components and to record a distance traveled by the motor vehicle (1) during operation of the drive unit (2), wherein the drive unit (2) is also provided and configured to determine an actual value of a classification parameter in addition to the distance traveled during operation of the drive unit (2) and to select a threshold value data set containing a threshold value from several threshold value data sets based on the actual value,wherein if the threshold contained in the selected threshold data set is exceeded by the amount of exhaust components related to the distance traveled, a fault in the drive system (2) is detected, wherein an environmental parameter describing an environment of the motor vehicle (1) is used as the classification parameter, . characterized by, that different comparison values ​​for the classification parameter are stored in the threshold data sets, wherein, to select the threshold data set, a correlation value is determined for each of the threshold data sets between the comparison value stored in it and the determined actual value of the classification parameter, and the threshold data set with the correlation value indicating the highest agreement is selected, wherein the threshold data set is only selected if the correlation value lies within a range of values ​​indicating an agreement between the comparison value and the determined actual value of the classification parameter. [7] Computer program product comprising instructions that cause the drive device (2) according to claim 6 to execute the method according to one or more of claims 1 to 5.

Images