Exhaust Gas Sensor Degradation Monitoring via Time Delay
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Solution Overview
Problem
Existing methods for monitoring exhaust gas sensor degradation in vehicles are intrusive, leading to inaccurate results due to restricted operating conditions and increased emissions, and are confounded by background noise.
Innovation Solution
A non-intrusive method using time delay and line length of exhaust gas sensor responses during commanded air-fuel ratio changes, specifically during deceleration fuel shut-off (DFSO) entries and exits, to determine sensor degradation without intrusive excursions, improving accuracy and reducing noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If intrusive data collection methods are used to monitor exhaust gas sensor degradation, then sensor degradation can be detected, but the method increases engine operation at non-desired air/fuel ratios resulting in increased fuel consumption and emissions
Solution Approach 1:
The exhaust gas sensor monitors its own degradation by analyzing its response during normal commanded air/fuel ratio transitions (such as DFSO events) without requiring external intrusive excursions. The sensor effectively serves itself by using its own operational data to detect degradation, eliminating the need for separate monitoring maneuvers that would increase emissions and fuel consumption.
Solution Approach 2:
The system uses feedback from the exhaust gas sensor's own response to commanded air/fuel ratio changes to detect degradation. By analyzing the sensor's response characteristics (time delay, line length) during normal operation, the system continuously monitors degradation without requiring additional intrusive actions, thus avoiding increased emissions and fuel consumption while maintaining detection accuracy.
2Measurement precision
If intrusive excursions are used to monitor exhaust gas sensor response, then sensor degradation can be identified, but the method is restricted to particular operating conditions that do not occur frequently enough for accurate monitoring
Solution Approach 1:
The system continuously monitors sensor degradation by analyzing the sensor's response during every commanded air/fuel ratio transition that occurs during normal vehicle operation, such as deceleration fuel shut-off events. This eliminates the need for periodic intrusive excursions and enables continuous degradation assessment, significantly increasing monitoring frequency and accuracy without restricting operation to specific conditions.
Solution Approach 2:
The monitoring system uses the exhaust gas sensor's response to any commanded air/fuel ratio transition (such as DFSO events) for degradation detection, making the monitoring applicable to multiple operating conditions rather than requiring a single specific excursion condition. This multi-functional approach allows continuous monitoring across various normal operating scenarios, increasing both frequency and accuracy of degradation detection.
3Measurement precision
If traditional exhaust gas sensor monitoring methods are used, then degradation can be detected, but large amounts of background noise confound accurate determination of sensor degradation
Solution Approach 1:
The system extracts specific degradation-indicative features (time delay and line length of sensor response to commanded air/fuel ratio changes) from the overall sensor signal, separating these meaningful parameters from the background noise. By focusing analysis on these extracted features rather than the raw sensor signal, the system achieves accurate degradation determination despite the presence of noise during normal operation.
Data Source
AI summary
A method for monitoring an exhaust gas sensor coupled in an engine exhaust is provided. In one embodiment, the method comprises indicating exhaust gas sensor degradation based on a time delay and line length of each sample of a set of exhaust gas sensor responses collected during a commanded change in air-fuel ratio. In this way, the exhaust gas sensor may be monitored utilizing robust parameters in a non-intrusive manner.