Method and system for torque control

Abstract

The present application provides methods and systems for torque control, and discloses methods and systems for detecting air-fuel ratio imbalances across all engine cylinders. In one example, a method (or system) may include indicating cylinder imbalance based on each of exhaust air-fuel ratio, exhaust manifold pressure, and cylinder torque weighted by a confidence factor determined based on operating conditions.

Description

technical field [0001] The present invention generally relates to methods and systems for determining inter-cylinder torque imbalance in an internal combustion engine of a vehicle. Background technique [0002] Engine emissions regulations require the detection of air-fuel ratio (AFR) imbalances among all engine cylinders. Inter-cylinder AFR can occur when the AFR within one or more cylinders differs from the AFR of other cylinders due to issues such as intake manifold leaks, fuel injector errors, exhaust gas recirculation errors, and fuel flow delivery problems out of balance. In addition to reducing emissions, an imbalance between cylinders can lead to torque errors that reduce engine performance and vehicle drivability. [0003] One example method for detecting cylinder-to-cylinder AFR imbalance is shown by Behr et al. in U.S. Patent No. 7,802,563. Wherein, the AFR imbalance is identified based on the response of the exhaust UEGO sensor at a frequency equal to or highe...

AI Technical Summary

Problems solved by technology

Likewise, if cylinder fuel or air injection is adjusted in response to an indication of an AFR imbalance during conditions when sensor outputs are unreliable, further AFR and torque issues may arise

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