System and method for increasing fuel economy of a vehicle including a SCR catalyst

Abstract

Methods and systems for increasing fuel economy of a vehicle including a SCR catalyst are presented. In one example, an amount of EGR provided to an engine is decreased in response to performance of the SCR being within a predetermined range of performance. The methods and systems may increase vehicle fuel economy while vehicle tailpipe emissions are achieved.

Description

technical field Background technique [0001] Engine operation may be adjusted to improve engine emissions or fuel economy. However, engine adjustments (eg, EGR amount and fuel injection timing) that improve fuel economy may also increase engine emissions. One way to increase tailpipe emissions without significantly increasing fuel consumption is to regulate the amount of exhaust gas recirculation (EGR) provided to the engine and to treat engine exhaust with a selective catalytic reduction system (SCR). Increasing the amount of EGR provided to the engine can reduce engine intake NOx without significantly increasing fuel consumption. Further, an exhaust-treating SCR located in the engine exhaust system can reduce intake NOx, thereby providing lower vehicle tailpipe NOx emissions. In this way, tailpipe NOx can be reduced by a combination of EGR and treated exhaust. However, when EGR is increased, the fuel economy of the engine may decrease slightly. As a result, engine fuel ...

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Problems solved by technology

However, the engine's fuel economy can be slightly reduced when EGR is increased

As a result, engine fuel economy can be lower than expected

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