Low dimensional three way catalyst model for control and diagnostics

Abstract

Embodiments for an engine exhaust are provided. In one example, a method comprises adjusting a fuel injection amount based on a fractional oxidation state of a catalyst, the fractional oxidation state based on reaction rates of a plurality of exhaust gas species throughout a catalyst longitudinal axis and a set of axially-averaged mass balance and energy balance equations for a fluid phase and a washcoat of the catalyst. In this way, a simplified catalyst model may be used to control air-fuel ratio.

Description

Technical field [0001] The invention relates to feedback control of the air-fuel ratio in an internal combustion engine. Background technique [0002] Effective conversion of exhaust emissions in gasoline engines involves maintaining the catalyst intake air-fuel ratio within a narrow window around stoichiometry. However, during actual engine operation, a slight excursion away from stoichiometry may occur. In order to increase the operating window and thus improve the emission performance, the catalyst usually includes ceria in order to provide a buffer for oxygen storage. In order to maintain the best catalyst performance, through feedback control of the engine air-fuel ratio, the stored oxygen can be maintained at a desired set point based on engine load and temperature calibration. Summary of the invention [0003] However, the inventor of the present invention has recognized the problems of the above method. Determining the level of oxygen stored in a catalyst generally invo...

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Problems solved by technology

However, during actual engine operation, slight excursions away from stoichiometry may occur

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