System and Method for Estimating Engine Exhaust Nitrogen Oxide Sensor Instability
First Claim
1. A vehicle, comprising:
- an engine;
an exhaust system connected to the engine and receiving exhaust gasses therefrom, the exhaust system having an exhaust aftertreatment system;
an Engine Out Nitrogen Oxide (EONOx) sensor connected to the exhaust system and providing a signal indicating Nitrogen Oxide (NOx) content in the exhaust gasses to at least one controller, the at least one controller being configured to;
predict instability in the EONOx sensor signal,validate the predicted instability in the EONOx sensor signal, andupon prediction and validation of instability in the EONOx sensor signal, latch the EONOx sensor signal to a stable value.
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Abstract
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.
7 Citations
20 Claims
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1. A vehicle, comprising:
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an engine; an exhaust system connected to the engine and receiving exhaust gasses therefrom, the exhaust system having an exhaust aftertreatment system; an Engine Out Nitrogen Oxide (EONOx) sensor connected to the exhaust system and providing a signal indicating Nitrogen Oxide (NOx) content in the exhaust gasses to at least one controller, the at least one controller being configured to; predict instability in the EONOx sensor signal, validate the predicted instability in the EONOx sensor signal, and upon prediction and validation of instability in the EONOx sensor signal, latch the EONOx sensor signal to a stable value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An exhaust aftertreatment system of a vehicle, comprising:
an Engine Out Nitrogen Oxide (EONOx) sensor connected to the exhaust aftertreatment system and providing a signal indicating Nitrogen Oxide (NOx) content in the exhaust gasses to at least one controller, the at least one controller being configured to; predict instability in the EONOx sensor signal, validate the predicted instability in the EONOx sensor signal, and upon prediction and validation of instability in the EONOx sensor signal, latch the EONOx sensor signal to a stable value. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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17. A method of estimating EONOx sensor signal instability in transient conditions and eliminating fluctuations in the EONOx sensor signal, comprising the steps of:
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predicting instability in the EONOx sensor signal by; calculating a pedal based driver demand torque, calculating a pedal based driver demand torque delta, calculating instability thresholds for the calculated pedal based driver demand torque delta, detecting instability in the calculated pedal based driver demand torque by comparing the calculated pedal based driver demand torque delta to the instability thresholds, and setting an instability flag predicting instability in the EONOx sensor signal when instability in the calculated pedal based driver demand torque is detected; validating the predicted instability in the EONOx sensor signal, and upon prediction and validation of instability in the EONOx sensor signal, latching the EONOx sensor signal to a stable value. - View Dependent Claims (18, 19, 20)
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Specification