Methods and systems for engine fuel and torque control

Abstract

Methods and systems are provided for accurately estimating intake aircharge based on the output of an intake oxygen sensor while flowing EGR, purge, or PCV hydrocarbons to the engine. The unadjusted aircharge estimate is used for engine fuel control while the hydrocarbon adjusted aircharge estimate is used for engine torque control. A controller is configured to sample the oxygen sensor at even increments in a time domain, stamp the sampled data in a crank angle domain, store the sampled data in a buffer, and then select one or more data samples corresponding to a last firing period from the buffer for estimating the intake aircharge.

Description

technical field [0001] The present description generally relates to an oxygen sensor coupled to an intake passage of an internal combustion engine. Background technique [0002] The engine may be equipped with an oxygen sensor coupled to the intake passage for determining the oxygen content of fresh intake air. In particular, the sensor measures the partial pressure of oxygen in the air charge after equalization. The air charge can be further corrected for the presence of diluents, which can react with oxygen at the sensor, thereby affecting the output of the sensor. For example, the oxygen sensor output is corrected for humidity, presence of hydrocarbons from EGR, purge fuel vapors, crankcase ventilation fuel vapors, etc. An example of such an approach is shown in US Patent Application 20140251285 by Surnilla et al. [0003] The corrected air charge estimate can then be used to control engine fueling. However, the inventors herein have recognized potential problems with...

AI Technical Summary

Problems solved by technology

As a result, the window for performing adaptive learning, such as adaptive learning of fuel and diagnostics of oxygen sensors, is limited

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