Systems and methods for split exhaust engine system

Abstract

The invention provides Systems and methods for a split exhaust engine system. Methods and systems are provided for operating a split exhaust engine system that provides blowthrough air and exhaust gasrecirculation to an intake passage via a first exhaust manifold and exhaust gas to an exhaust passage via a second exhaust manifold. In one example, an air-fuel control method for the engine system may include flowing air from the intake manifold through a plurality of engine cylinders to a junction of the exhaust passage and a bypass passage in response to a condition, the junction positioned along the exhaust passage between first and second emission control devices. The method may further include flowing exhaust gas to the first emission control device while flowing the air to the junction.

Description

technical field [0001] The present specification generally relates to methods and systems for split-flow exhaust engines including exhaust gas recirculation. Background technique [0002] The engine may use a boosting device, such as a turbocharger, to increase engine power density. However, due to the increased combustion temperature, engine knock may occur. Knock is especially problematic under boosted conditions due to high charge temperatures. The present inventors have realized that knocking can be reduced and engine efficiency can be improved by using an engine system with a split exhaust system, where the first exhaust manifold delivers exhaust gas recirculation (EGR) to the compressor of the turbocharger. upstream of the intake of the engine, and wherein the second exhaust manifold routes the exhaust to the turbine of the turbocharger in the exhaust of the engine. In such an engine system, each cylinder may include two intake valves and two exhaust valves, with a ...

AI Technical Summary

Problems solved by technology

However, this can result in high levels of hydrocarbons and carbon monoxide in the exhaust

When the second emission control device is a three-way catalyst, non-stoichiometric exhaust gas entering the second emission control device can result in reduced three-way catalyst function, and thus increased emissions

When the secondary emission control device is a gasoline particulate filter, increased levels of hydrocarbons can lead to increased soot loading of the GPF, and thus increased emissions

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