Exhaust Aftertreatment Sensor Offset Diagnosis for NOx Accuracy
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing exhaust aftertreatment systems face challenges in accurately diagnosing sensor offsets and faults, particularly in NOx sensors, which affect the performance and compliance with stringent emissions regulations.
Innovation Solution
A method and system for diagnosing exhaust aftertreatment sensors, specifically NOx sensors, by determining sensor offset and gain through a controller that monitors and analyzes data from inlet and outlet temperature sensors and tailpipe NOx sensors, using a series of circuits to filter and compare sensed values with predefined thresholds, enabling accurate sensor health assessment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sensor offset correction is implemented through complex diagnostic algorithms, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The system performs preliminary diagnostic actions by monitoring sensor readings during specific operating conditions (e.g., when NOx sensor should read zero or known values) and calculating offset corrections in advance. The controller stores these offset values and applies them proactively to subsequent measurements, resolving the technical contradiction by achieving high measurement precision through pre-computed corrections rather than complex real-time algorithms.
2Reliability
If continuous sensor monitoring is performed to detect faults early, then reliability is improved, but use of energy increases
Solution Approach 1:
The controller performs sensor fault monitoring periodically rather than continuously, activating diagnostic routines at predetermined intervals or under specific triggering conditions. This periodic monitoring approach maintains high reliability by detecting sensor faults when they occur, while significantly reducing energy consumption by keeping the diagnostic logic dormant during normal operation.
3Measurement precision
If multiple sensors are deployed to improve diagnostic accuracy, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The existing NOx sensors in the aftertreatment system are made multi-functional by programming the controller to use them for both their primary function (emissions monitoring) and diagnostic functions (offset detection, fault diagnosis). The same sensor hardware serves multiple purposes through software-based diagnostic algorithms, achieving improved diagnostic accuracy without adding physical sensor complexity.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Systems and methods for diagnosing a sensor of an exhaust aftertreatment system can include a controller determining that an amount of an exhaust gas constituent at a particular location is expected to be at or below a predefined value for a period of time, and receiving data indicative of a sensed amount of the exhaust gas constituent from the sensor of the exhaust aftertreatment system during the period of time. The controller determines, based on the sensed amount of the exhaust gas constituent, an amount of offset affecting the sensor of the exhaust aftertreatment system, and initiates an action based on the determined amount of offset to diagnose the sensor.