EONOx Sensor Signal Latching for Transient Torque Instability
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Solution Overview
Problem
Engine exhaust nitrogen oxide sensors experience instability during rapid changes in driver demanded torque, leading to fluctuations in sensor signals, which complicates robust on-board diagnostics and emissions control in diesel engines.
Innovation Solution
A system and method that predicts and validates EONOx sensor signal instability by calculating driver demand torque and setting instability flags, then latches the sensor signal to a stable value, ensuring accurate monitoring and control during transient conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If EONOx sensor signal status changes are responded to immediately, then responsiveness to sensor changes is improved, but sensor signal instability during transients causes false diagnostics and control errors
Solution Approach 1:
The system performs preliminary detection of transient conditions (rapid driver demanded torque changes) before the sensor instability occurs. By detecting the transient condition first and preemptively latching the sensor signal during these periods, the system prevents unstable sensor readings from triggering false diagnostics while maintaining quick response to actual sensor changes when conditions are stable.
Solution Approach 2:
The system dynamically adjusts its response to sensor signals based on operating conditions. During transient conditions (rapid torque changes), the system latches the sensor signal to a stable value, effectively freezing updates. During stable conditions, the system responds normally to sensor changes. This dynamic adaptation allows the system to maintain reliability during transients while preserving responsiveness during normal operation.
2Stability of the object's composition
If maturity debounce time is used to filter unstable sensor signals, then sensor signal stability is improved, but response time to detect actual sensor changes is delayed
Solution Approach 1:
Instead of applying a uniform debounce time to all sensor signal changes, the system applies signal latching selectively only during transient conditions (rapid driver demanded torque changes). By identifying the specific local condition (transient state) that causes instability and applying the stabilization mechanism only there, the system maintains sensor signal stability when needed without introducing unnecessary delays during normal operation.
3Productivity
If EONOx sensor readings are used during rapid torque changes, then real-time emissions monitoring is maintained, but sensor signal instability compromises control accuracy
Solution Approach 1:
The system detects transient conditions (rapid driver demanded torque changes) before they affect sensor readings and preemptively latches the sensor signal to a stable value. This preliminary action prevents unstable readings from being used in control calculations during transients, maintaining measurement precision without sacrificing real-time monitoring capability during stable conditions.
Data Source
AI summary
A system and method is provided for estimating engine exhaust nitrogen oxide sensor signal instability in transient conditions, for example when rapid changes occur in driver demanded torque, and for eliminating fluctuations in EONOx sensor signal status, in order to have more robust on-board diagnostics monitoring and exhaust nitrogen oxide control. The system and method predicts EONOx sensor signal instability by comparing a calculated pedal based driver demand torque delta to calculated instability thresholds and instability threshold hysteresis margins, and generates instability flags. The system and method further validates any predicted EONOx sensor signal instability by observation. Upon validation of the predicted EONOx sensor signal instability, the system and method latches the EONOx sensor signal status to a stable value.