NOx Adsorption Catalyst Regeneration with Dual Lambda Sensor Plausibility
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Solution Overview
Problem
Internal combustion engines operating in stratified mode experience increased NOx emissions, which cannot be completely mitigated by traditional three-way catalytic converters, and NOx storage catalysts require regeneration due to their finite capacity, necessitating accurate detection of regeneration phases.
Innovation Solution
A method utilizing a first and second broadband lambda sensor situated in the exhaust gas flow direction, with an NOx adsorption catalyst, where the catalyst is regenerated using a rich or stoichiometric air/fuel mixture, and a plausibility check/correction of the first lambda signal is performed using the second lambda signal to ensure accurate signal processing and enhanced regeneration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single broadband lambda sensor is used for detecting exhaust gas composition during NOx storage catalyst regeneration, then the device complexity is reduced, but the measurement precision and reliability of lambda signal deteriorate due to potential sensor errors and signal deviations
Solution Approach 1:
The patent places the first broadband lambda sensor at a specific location upstream of the NOx storage catalyst to monitor exhaust gas composition before catalyst intervention, while the second narrowband lambda sensor is positioned downstream to detect oxygen depletion. Each sensor is optimally positioned for its specific measurement function, with the first sensor capturing raw exhaust composition and the second sensor specifically detecting regeneration status through oxygen breakthrough detection.
Solution Approach 2:
The patent implements a plausibility check mechanism that compares the lambda signal from the first broadband lambda sensor with the signal from the second narrowband lambda sensor before using the first sensor's signal for control decisions. This comparison serves as a preliminary validation to detect and correct potential sensor errors, signal deviations, or characteristic curve shifts, ensuring reliable regeneration control.
2Speed
If the first broadband lambda sensor signal is used directly for control without validation, then the response time is reduced, but the reliability of the control system deteriorates due to undetected sensor errors
Solution Approach 1:
The patent establishes a feedback mechanism where the lambda signal from the first broadband lambda sensor is continuously compared with the signal from the second narrowband lambda sensor. The control unit evaluates the plausibility of the first sensor's signal by comparing it with the second sensor's signal, which serves as a reference. This feedback loop enables real-time error detection and correction without significantly delaying the control response, as the comparison is performed in parallel with the control process.
3Reliability
If a plausibility check mechanism is implemented comparing two lambda sensors, then the reliability of lambda signal is improved, but the device complexity increases
Solution Approach 1:
The patent combines the functions of two different lambda sensors (broadband and narrowband) into a unified plausibility check system. The first broadband lambda sensor provides comprehensive exhaust gas composition information, while the second narrowband lambda sensor specifically monitors oxygen levels for regeneration detection. By merging their signals in the control unit, the system achieves mutual validation and error detection, where each sensor type compensates for the limitations of the other, improving overall reliability without requiring a third sensor or complex additional hardware.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables a stronger regeneration of the NOx adsorption catalyst, detects errors in the first sensor signal, and corrects deviations, ensuring better thermodynamic equilibrium and more reliable NOx emission management, particularly during intensified regeneration phases.
Implementation Method 1
an NOx adsorption catalyst which makes available a first lambda signal and cyclically stores the NOx emissions of the internal combustion engine and is regenerated
Implementation Method 2
a first broadband lambda sensor which makes available a first lambda signal, an NOx adsorption catalyst and a second broadband lambda sensor which makes available a second lambda signal
Implementation Method 3
the NOx adsorption catalyst cyclically stores the NOx emissions of the internal combustion engine and is regenerated, and in which the plausibility check/correction of the first lambda signal is performed using the second lambda signal
Data Source
AI summary
A method for operating an internal combustion engine, in whose exhaust region, in the direction of flow of the exhaust gas, there are situated a first broadband lambda sensor which makes available a first lambda signal, an NOx adsorption catalyst and a second broadband lambda sensor which makes available a second lambda signal, in which the NOx adsorption catalyst cyclically stores the NOx emissions of the internal combustion engine, and is regenerated within the scope of a nominal regeneration by the operation of the internal combustion engine using a rich/stoichiometric air/fuel mixture, and a device for carrying out the method are provided. An intensified regeneration, compared to a nominal regeneration, of the NOx adsorption catalyst is undertaken, which supports a better setting of the thermodynamic equilibrium in the exhaust gas compared to the nominal regeneration. At the end of the intensified regeneration, at a still rich/stoichiometric air/fuel mixture, a plausibility check/correction of the first lambda signal using the second lambda signal is provided.