METHODS AND SYSTEMS FOR AN OXYGEN SENSOR

摘要

Methods and systems are provided for accurately learning the zero point of an intake gas oxygen sensor in varying ambient humidity conditions. The learned zero point is corrected based on an estimated ambient humidity to calibrate the reading for dry air conditions or standard humidity conditions. EGR control is performed by comparing the output of an intake oxygen sensor during EGR conditions relative to the humidity-corrected zero point.

主权项

1. A method for an engine with a turbocharger, comprising:
cooling boosted intake charge with a charge air cooler; estimating an ambient humidity via an intake humidity sensor while learning a reference point for an intake oxygen sensor at a reference intake pressure, the reference point corresponding to an oxygen sensor reading when no EGR is present; combusting cooled intake charge, including EGR, with directly injected fuel in the engine; adjusting valve timing of one of an intake and exhaust valve of the engine; passing turbocharger compressor bypass flow through a ventuir to generate a draw on an accessory passage; correcting the learned reference point based on the estimated ambient humidity; and adjusting an opening of an EGR valve based on the correcting.