Exhaust Aftertreatment Sensor Offset Detection During Low-NOx Conditions
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Solution Overview
Problem
Existing exhaust aftertreatment systems face challenges in accurately diagnosing sensor offsets, particularly in nitrous oxide (NOx) sensors, which can lead to inconsistent performance and non-compliance with stringent emissions regulations.
Innovation Solution
A method and system for diagnosing exhaust aftertreatment system sensors by determining the amount of offset affecting the sensors, involving a controller that receives data from sensors during periods of expected low NOx output, filters and compares sensed values to predefined thresholds, and initiates actions based on the determined offset to diagnose sensor health.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If exhaust aftertreatment systems use sensors to monitor emissions, then emission compliance can be achieved, but sensor offsets can cause inaccurate measurements and inconsistent performance
Solution Approach 1:
The system performs preliminary diagnostic actions by monitoring sensor readings during specific engine operating conditions (low load, high exhaust flow) where NOx emissions are naturally low. This preliminary monitoring allows the system to detect sensor offsets before they cause compliance failures, maintaining measurement accuracy without requiring additional hardware.
Solution Approach 2:
The system implements feedback by continuously comparing expected NOx levels (based on engine operating conditions and aftertreatment efficiency) with actual sensor readings. When discrepancies indicate sensor offset, the system adjusts monitoring frequency and triggers diagnostic routines, creating a closed-loop system that maintains reliable measurements adaptively.
2Reliability
If the system continuously monitors sensor readings to detect offsets, then sensor health can be maintained, but computational resources and processing time increase
Solution Approach 1:
The system uses periodic monitoring strategically tied to specific engine operating conditions rather than continuous monitoring. It activates diagnostic routines during low-load, high-flow conditions where NOx emissions are naturally suppressed, allowing offset detection without requiring constant computational resources. This periodic approach maintains reliability while minimizing processing time.
Solution Approach 2:
The system changes monitoring parameters dynamically based on engine operating conditions. During normal operation, monitoring occurs at standard intervals, but during specific conditions (low load, high flow rate, certain temperature ranges), the system increases monitoring frequency and applies different evaluation thresholds, optimizing the balance between diagnostic capability and processing requirements.
Data Source
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.