DE102021214723A1 - Method for predictive diagnosis in a diesel exhaust system - Google Patents

Abstract

The present disclosure proposes a method (100) for predictive diagnosis in a diesel exhaust system and an electronic control unit (ECU (104)) therefor. In step 201, the ECU (104) retrieves a modeled temperature value. In step 202, the ECU (104) receives a second temperature value from the second temperature sensor (103) located downstream of a catalytic converter (101). In step 203, the ECU (104) calculates a difference between the second values and the modeled value depending on a first set of inputs, such as a status of a DPF (105), regeneration count data for the DPF (105). In step 204, the ECU (104) uses this calculation to predict a failure in the diesel exhaust system. The failure prognosis occurs when the calculated difference remains constant for a predefined period of time.

Description

field of invention

The present disclosure relates to a method for predictive diagnosis in a diesel exhaust system and an electronic control unit therefor.

Background of the Invention

In order to meet the strict particle and emission targets, catalytic converters such as the diesel oxidation catalytic converter (DOC)/NOx storage catalytic converter (NSC) together with a diesel particulate filter (DPF) are mandatory in a vehicle's exhaust system. The diesel particle filter accumulates and collects the soot particles. When the soot particles have completely accumulated in the DPF in a certain interval, they create a back pressure in the engine and a resistance to the exhaust gas flow. Therefore, the DPF needs to be cleaned periodically through a process commonly referred to as regeneration. For effective regeneration, the soot in the DPF must be properly burned. This requires a proper exothermic reaction in the catalyst (DOC/NSC). The exothermic reactions are also dependent on other components of the vehicle's air and fuel system. These are the inputs to the actual exothermic reaction. It is possible to indicate anomalies in the exhaust system when the actual values of parameters such as the temperature in the catalytic converter have deviated from the expected or calibrated values. Predicting system variations and component failures requires a robust algorithm that can predict component failures in advance.

The patent application US5941918A entitled "Automotive on-board monitoring system for catalytic converter evaluation" discloses an on-board diagnostic system for motor vehicles, in which the system determines whether the vehicle continuously meets the statutory emission standards by only monitoring hydrocarbon and carbon monoxide emissions detected at a point downstream of the three-way catalyst. All collected emission data is combined with a basic vehicle function, e.g. B. speed, correlated and sorted into a number of histograms that correspond to the operating conditions of the vehicle specified by the emissions regulations. When a failure occurs, histogram diagnostic routines are sequentially executed to determine which vehicle emissions system has failed.

character list

• 1 zeigt einen Abschnitt eines Dieselabgassystems (100); und
• 2 stellt die Verfahrensschritte (200) der prädiktiven Diagnose im Dieselabgassystem (100) dar.

An embodiment of the invention will be described with reference to the following accompanying drawings:

• 1 shows a portion of a diesel exhaust system (100); and
• 2 represents the method steps (200) of the predictive diagnosis in the diesel exhaust system (100).

Detailed description of the drawings

1 shows a portion of a diesel exhaust system (100). The diesel exhaust system comprises at least a first temperature sensor (102) and a second temperature sensor (103) as well as other components such as a diesel particulate filter (DPF (105)), a diesel oxidation catalyst (101) or a NOx storage catalyst (101) (hereinafter referred to as catalyst (101 ) referred to) and the like. The first temperature sensor (102) is arranged upstream of the catalytic converter (101). The second temperature sensor (103) is arranged downstream of the catalytic converter (101) and upstream of the diesel particulate filter (DPF (105)). The first temperature sensor (102) and the second temperature sensor (103) are in communication with an electronic control unit (ECU (104)).

The first temperature sensor (102) measures the temperature value upstream of the catalytic converter (101). The second temperature sensor (103) measures the temperature value downstream of the catalytic converter (101). The DPF (105) is a filter used to remove diesel particulate matter or soot from the exhaust gas of a diesel engine. The accumulated soot particles are continuously or periodically removed from the filter by thermal regeneration. This regeneration of the DPF (105) is achieved by programming the engine to run (when the filter is full) in such a way that it increases the exhaust gas temperature and burns off the soot that has accumulated in the DPF (105). The catalytic converter (101) performs exothermic reactions during the regeneration process to increase the exhaust gas temperature. However, the temperature difference must not exceed a specified threshold during the regeneration process. This temperature differential is controlled by software in the ECU (104) commonly known as observer correction. The observer calculates a modeled temperature value that corresponds to the temperature that would ideally be observed downstream of the catalyst. The observer also ensures that the temperature difference is maintained through various measures such as post-injection of fuel and the like.

2 shows the procedural steps of the predictive diagnosis in the diesel exhaust system. The diesel exhaust system is the same as shown in FIG 1 described. The ECU (104) is adapted for predictive diagnostics in the diesel exhaust system. The ECU (104) is configured to carry out the method steps. In step 201, the ECU (104) retrieves a modeled temperature value. This corresponds to the ideal value of the temperature downstream of the catalytic converter (101) calculated by the observer. In step 202, the ECU (104) receives a second temperature value from the second temperature sensor (103). The second temperature sensor (103) measures the temperature value downstream of the catalytic converter (101).

In step 203, the ECU (104) calculates a difference between the second value and the modeled value in response to a first set of inputs. The first set of inputs includes status of the DPF (105), regeneration count data for the DPF (105). The calculation is performed when the DPF (105) status is in regeneration mode and the regeneration count is below a predefined threshold. In step 204, the ECU (104) uses this calculation to predict a failure in the diesel exhaust system. The failure prognosis occurs when the calculated difference remains constant for a predefined period of time. This ensures that only a stable high temperature is considered for the predictive diagnosis and minor anomalies are disregarded. For example, in one embodiment of the present invention, the failure prediction occurs only when the temperature difference during the regeneration phase exceeds a predetermined threshold (e.g., 100 Kelvin) for at least 15 seconds depending on the other first set of inputs.

The regeneration count data is important to ensure that regeneration has taken place at least once. The first regeneration is important because catalysts (101) show a certain loss of activity in the short initial period. After this initial loss of activity, the performance of the catalyst (101) remains stable over a long period of time. For this reason, new catalytic converters (101) should be "post-matured" before emission tests. If post-ripening is not performed on a fresh EGT, it will affect the exothermic reaction performance. This improves light-off performance and conversion efficiency of a Diesel Oxidation Catalyst (101) (DOC). If no initial regeneration has taken place, there is no consistency or stability in the temperature history. The consideration of the first regeneration is important to avoid misreading the performance of the catalytic converter (101). Further note that it is natural or obvious that the temperature difference between the first temperature sensor (102) and the second temperature sensor (103) in the regeneration mode is higher than the predefined value when the regeneration count exceeds a predetermined number. Therefore, this value is of utmost importance in predicting system problems.

This idea of developing a new method that diagnoses or predicts the system postpones component failure. These new procedural steps were developed to predict the performance of the system. If the observer correction (i.e. the temperature difference between the first and second temperature sensors (103)) reaches the maximum calibrated threshold, this will result in a significantly shorter vehicle life. This indicates the anomaly in the system and a possible failure of a component. To avoid this cause, an error is triggered in the system. In one embodiment of the present system, the error response lamp is integrated on the dashboard to inform the end customer of the likely problems in the system.

It should be understood that the embodiments described in the above detailed description are merely illustrative and do not limit the scope of this invention. Any changes in the method of predictive diagnostics in a diesel exhaust system are intended to form a part of this invention. The scope of the invention is only limited by the claims.

QUOTES INCLUDED IN DESCRIPTION

This list of the documents cited 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

• US5941918A [0003]

Claims (8)

A method for predictive diagnosis in a diesel exhaust system, the diesel exhaust system comprising at least a first temperature sensor (102) and a second temperature sensor (103), the first temperature sensor (102) being arranged upstream of the catalytic converter (101), the second temperature sensor (103) being arranged downstream from the catalytic converter (101) and upstream of a diesel particulate filter (DPF (105)), the first and second temperature sensors being in communication with an electronic control unit (ECU (104)), the method comprising: retrieving a modeled temperature value; receiving a second temperature value from the second temperature sensor (103); calculating a difference between the second value and the modeled value in response to a first set of inputs; Predict a failure in the diesel exhaust system based on the calculation. Method for predictive diagnosis in a diesel exhaust system according to claim 1 wherein the first set of inputs includes a status of the DPF (105), regeneration count data for the DPF (105). Method for predictive diagnosis in a diesel exhaust system according to claim 1 wherein the calculation is performed when the DPF (105) status is in regeneration mode and the regeneration count is below a predefined threshold. Method for predictive diagnosis in a diesel exhaust system according to claim 1 , where a failure is predicted if the calculated difference remains constant for a predefined period of time. Electronic control unit (ECU (104)) adapted for predictive diagnostics in a diesel exhaust system, the diesel exhaust system comprising at least a first temperature sensor (102) and a second temperature sensor (103), the first temperature sensor (102) upstream of the catalytic converter (101 ) is arranged, the second temperature sensor (103) is arranged downstream of the catalytic converter (101) and upstream of a diesel particulate filter (DPF (105)) and the first and second temperature sensors are in communication with the ECU (104), the ECU ( 104) is configured to: retrieve a modeled temperature value; receive a second temperature value from the second temperature sensor (103); calculate a difference between the second value and the modeled value depending on a first set of inputs; predict a failure of the diesel exhaust system based on this calculation. Electronic control unit (ECU (104)) for predictive diagnostics in a diesel exhaust system according to claim 5 is adjusted, wherein the first set of inputs includes a status of the DPF (105), a regeneration count for the DPF (105). Electronic control unit (ECU (104)) for predictive diagnostics in a diesel exhaust system according to claim 5 is adjusted, the calculation being performed when the DPF (105) status is in regeneration mode and the regeneration count is below a predefined threshold. Electronic control unit (ECU (104)) for predictive diagnostics in a diesel exhaust system according to claim 5 is adjusted, with the prediction of a failure occurring when the calculated difference remains constant for a predefined period of time.

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