DE-102025127017-B4 - Method for adapting an SCR system to an exhaust aftertreatment device

DE102025127017B4DE 102025127017 B4DE102025127017 B4DE 102025127017B4DE-102025127017-B4

Abstract

Method for adapting an SCR system (12) to an exhaust aftertreatment device (10) for aftertreating exhaust gas from an internal combustion engine of a motor vehicle, wherein: - the SCR system (12) features: ◯ at least one SCR catalyst (14, 16); ◯ at least one metering device (26) by means of which a reducing agent (34) can be introduced into the exhaust gas; ◯ a reducing agent tank (32) for receiving the reducing agent (34); ◯ a quality sensor (38) for determining the quality of the reducing agent (34); ◯ a level sensor (36) for detecting the level of the reducing agent (34) in the reducing agent tank (32); and ◯ a control unit (40); - the control unit (40) stores a quality end value in a non-volatile memory at one end of a first driving cycle of the motor vehicle, which characterizes a quality of the reducing agent (34) taken up in the reducing agent tank (32) at the end determined by means of the quality sensor (38); - then, if at the beginning of a second driving cycle following the first driving cycle, a standby operation of the control unit (40) that occurred between the first and the second driving cycle is detected, and a refueling process that occurred between the first and the second driving cycle is detected by evaluating measured values of the level sensor (36) for the level of reducing agent in the reducing agent tank (34), a comparison of the final quality value with a starting quality value determined at the beginning of the second driving cycle of the vehicle by means of the control unit (40) is carried out, which provides an initial valid comparison to the beginning by means of the The quality of the reducing agent (34) taken up in the reducing agent tank (32) is characterized by the quality sensor (38); - if a difference determined by comparison between the final quality value and the initial quality value is greater than a predefinable threshold value, a correction is made to the dosage quantities of the reducing agent (34) to be introduced into the exhaust gas by means of the dosing device (26); and - if the difference between the final quality value and the initial quality value determined by the comparison is less than or equal to the threshold value, the correction of the dosage quantities to be introduced is omitted.

Inventors

Nhat Phan
Matthias Hölz
Philipp Heinemeyer

Assignees

Mercedes-Benz Group AG

Dates

Publication Date: 20260513
Application Date: 20250710
Priority Date: 20240727

Claims (4)

Method for adapting an SCR system (12) of an exhaust aftertreatment device (10) for aftertreating exhaust gas from an internal combustion engine of a motor vehicle, wherein: - the SCR system (12) comprises: ◯ at least one SCR catalyst (14, 16); ◯ at least one metering device (26) by means of which a reducing agent (34) can be introduced into the exhaust gas; ◯ a reducing agent tank (32) for receiving the reducing agent (34); ◯ a quality sensor (38) for determining the quality of the reducing agent (34); ◯ a level sensor (36) for detecting the level of the reducing agent (34) in the reducing agent tank (32); and ◯ a control unit (40); - the control unit (40) stores a final quality value in non-volatile memory at the end of the first driving cycle of the vehicle, which characterizes the quality of the reducing agent (34) taken up in the reducing agent tank (32) at that end, as determined by the quality sensor (38); - then, if at the beginning of a second driving cycle following the first driving cycle, a standby operation of the control unit (40) that occurred between the first and second driving cycles is detected, and a refueling process that occurred between the first and second driving cycles is detected by evaluating measured values from the level sensor (36) for the level of reducing agent in the reducing agent tank (34), a comparison of the final quality value with a starting quality value determined by the control unit (40) at the beginning of the second driving cycle of the vehicle is carried out, which characterizes an initial valid quality of the reducing agent (34) taken up in the reducing agent tank (32) at that beginning, as determined by the quality sensor (38); - if a difference determined by comparison between the final quality value and the initial quality value is greater than a predefinable threshold value, a correction is made to the dosage quantities of the reducing agent (34) to be introduced into the exhaust gas by means of the dosing device (26); and - if the difference determined by comparison between the final quality value and the initial quality value is less than or equal to the threshold value, the correction of the dosage quantities to be introduced is omitted.
Procedure according to Claim 1 , characterized in that, after the start of the second driving cycle, a comparison of the total quantity of the reducing agent (34) introduced into the exhaust gas by means of the metering device (26) during the second driving cycle up to a comparison time, which is determined by adding the metered quantities introduced, is repeatedly carried out by means of the control unit (40) with a predefinable value, - the quality of the reducing agent is repeatedly determined, and - if it is determined that the total quantity exceeds the value and no change in quality is determined, a refueling detection is switched off.
Procedure according to Claim 1 , characterized in that the SCR system (12) comprises a further SCR catalyst (16) and a further metering device (38), wherein, after the start of the second driving cycle, - by means of the control unit (40) during the second driving cycle up to a comparison time, a first total quantity of the reducing agent (34) introduced into the exhaust gas by means of the metering device (26), which is determined by adding the introduced first metering quantities, and a second total quantity of the reducing agent (34) introduced into the exhaust gas by means of a second metering device (38), which is determined by adding the introduced second metering quantities, are added to a total quantity introduced by the first and second metering devices; - by means of the control unit (40) a comparison of the total quantity with a predefinable value is repeatedly carried out; - the quality of the reducing agent is repeatedly determined, and - if it is determined that the total quantity introduced by the first and second dosing units exceeds the value and no change in quality is detected, a refueling detection is switched off.
Method according to one of the preceding claims, characterized in that, if the difference between the final quality value and the initial quality value determined by the comparison is greater than the predefinable threshold value, the correction of the dosage quantities of the reducing agent (34) to be introduced into the exhaust gas by means of the dosing device (26) is carried out by multiplying a long-term adaptation factor, which is stored in the control unit (40) for an adaptation of the SCR system (12), in particular as a learning value, with a medium factor.

Description

The invention relates to a method for adapting an SCR system of an exhaust aftertreatment device for the aftertreatment of exhaust gas from an internal combustion engine of a motor vehicle. The DE 10 2013 216 894 A1 A known SCR catalyst system of an internal combustion engine, wherein the SCR catalyst system has a sensor for monitoring the quality of a reducing agent used for catalysis, in which it is provided in particular that raw data supplied by the sensor during operation of the internal combustion engine are adjusted by means of a correction value. The EP 3 175 095 B1 Disclosing a method for operating a vehicle's exhaust system, which includes checking whether reducing agent has been added to a storage container. Within a predetermined period, several measurements are recorded, the magnitude and frequency of which are used to assess the quality of the reducing agent. From the DE 10 2005 012 393 A1 A system for diagnosing the quality of a reagent solution intended for feeding into an emission catalyst of an internal combustion engine is known. Devices are provided to determine a quality value corresponding to the quality of the reagent solution. The CN 1 13 217 159 A discloses a method and a device for avoiding false alarms in the event of urea quality defects and is applicable in the field of exhaust gas purification of engines. The DE 10 2018 210 103 A1 A method for operating an SCR catalyst is known, wherein a deviation of a concentration of a reducing agent solution from a target value is determined and a change in an injected dosage quantity of the reducing agent solution is made in relation to a requested dosage quantity depending on the deviation. The object of the present invention is to create a method so that a particularly low-emission operation of a motor vehicle can be achieved. This problem is solved by a method with the features of claim 1. Advantageous embodiments with expedient further developments of the invention are specified in the remaining claims. The invention relates to a method for adapting an SCR system (SCR - Selective Catalytic Reduction) of an exhaust aftertreatment device for treating the exhaust gas of an internal combustion engine of a motor vehicle, in particular a motor vehicle and, most especially, a passenger car. The internal combustion engine can provide the exhaust gas during operation, with the exhaust gas flowing through the exhaust aftertreatment device and thus the SCR system. The SCR system comprises at least one SCR catalyst and at least one metering device, also referred to as the first metering device, by means of which a reducing agent, in particular a liquid, can be introduced, in particular injected, into the exhaust gas. When the metering device is mentioned before and below, this refers, unless otherwise specified, to the first metering device. The metering device is also referred to as the metering unit. Preferably, the reducing agent is an aqueous urea solution. The SCR system also includes a reducing agent tank, often simply referred to as a tank, for holding the reducing agent. The SCR system also features a quality sensor that measures the quality of the reducing agent, particularly the amount contained in the tank. For example, the quality is characterized by the urea content of the reducing agent, i.e., the amount of urea present in the tank. The SCR system also includes a level sensor that detects the level of the reducing agent in the tank, specifically the amount of reducing agent currently in the tank. Thus, the level sensor can detect changes in the level of the reducing agent in the tank. In particular, the level sensor can detect an increase in the fluid level in the reducing agent tank, for example, as a result of refilling. The SCR system also includes a control unit, also known as an electronic computer. In this process, the control unit stores a final quality value at the end of the first driving cycle of the vehicle. This final quality value characterizes the urea content of the reducing agent, as determined by the quality sensor at the end of the first driving cycle. This final quality value is stored in non-volatile memory within the control unit at the end of the first driving cycle. Unless otherwise specified, this refers to a memory that stores data values, including the final quality value, even after the control unit's post-run cycle has ended. This ensures that the stored values, and therefore the final quality value, are available again at the start of the second driving cycle. In this process, at the beginning of a second driving cycle of the vehicle, specifically one that directly follows the first driving cycle and a refueling operation, the control unit compares the final quality value with a starting quality value. The characteristic that the second driving cycle directly follows the first means that no further driving cycle of the vehicle occurs between the first and second driving cycles. The refueling operation is