Methods and systems for an oxygen sensor
First Claim
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1. An engine method, comprising:
- learning a reference point for an intake oxygen sensor at a reference intake pressure during selected engine idling conditions, including correcting an output of the sensor estimated at the reference intake pressure with a correction factor based on ambient humidity; and
adjusting engine EGR flow, via an EGR valve, based on an intake oxygen concentration estimated by the sensor relative to the learned reference point and a change in intake pressure from the reference intake pressure.
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Abstract
Methods and systems are provided for accurately learning the zero point of an intake gas oxygen sensor during selected idling conditions. The learned zero point is used to infer EGR flow and accordingly adjust EGR valve control. In addition, EGR valve leakage is diagnosed based on the zero point learned during an idle adaptation relative to a zero point learned during a DFSO adaptation.
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Citations
18 Claims
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1. An engine method, comprising:
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learning a reference point for an intake oxygen sensor at a reference intake pressure during selected engine idling conditions, including correcting an output of the sensor estimated at the reference intake pressure with a correction factor based on ambient humidity; and adjusting engine EGR flow, via an EGR valve, based on an intake oxygen concentration estimated by the sensor relative to the learned reference point and a change in intake pressure from the reference intake pressure. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method for an engine, comprising:
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estimating a first output of an intake oxygen sensor at a first intake pressure estimated by an intake pressure sensor during a first engine idle since engine start, the intake oxygen sensor and intake pressure sensor coupled upstream of an intake throttle and downstream of a charge air cooler; learning a relationship between the first intake oxygen sensor output and the first intake pressure; and adjusting EGR flow to the engine, via an EGR valve, at a second intake pressure estimated by the intake pressure sensor based on a second output of the intake oxygen sensor estimated at the second intake pressure and the learned relationship. - View Dependent Claims (13, 14, 15, 16)
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17. An engine system, comprising:
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an engine including an intake manifold; a turbocharger including an exhaust turbine and an intake compressor; a charge air cooler coupled downstream of the compressor; an intake oxygen sensor coupled to the intake manifold downstream of the charge air cooler and upstream of an intake throttle; a pressure sensor coupled to the intake manifold downstream of the charge air cooler and upstream of the intake throttle; an EGR system including an EGR passage and EGR valve for recirculating exhaust residuals from downstream of the turbine to upstream of the compressor; and a controller with computer readable instructions for; during a first engine idle since an engine start, learning a reference point for the oxygen sensor at a reference intake pressure; and adjusting an opening of the EGR valve based on an intake oxygen concentration estimated by the sensor relative to the learned reference point, and further based on an intake pressure relative to the reference intake pressure. - View Dependent Claims (18)
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Specification