Engine exhaust system and method

Abstract

Systems and methods are provided for operating an engine exhaust system. In one example, a system comprises a first valve, and a second valve coupled to the first valve via a shaft. A first position of the shaft situates the first valve closed and the second valve open, a second position situates the second valve closed and the first valve open by a first amount, and a third position situates the second valve closed and the first valve open by a second, larger amount.

Description

【Technical field】 [0001] The present invention generally relates to exhaust systems and methods for internal combustion engines configured to capture hydrocarbon emissions. 【Background technique】 [0002] Engine exhaust systems utilize hydrocarbon retention devices, such as hydrocarbon (HC) traps, to retain cold start emissions (HC storage). The retained HC can be re-reacted at a later time (eg after the exhaust gas temperature has become sufficiently warm) or recirculated into the engine intake system (HC purging). The engine exhaust system may also be connected to an engine exhaust gas recirculation (EGR) system, where EGR flow is used to draw stored HC from the HC trap. For example, one or more exhaust valves may be used to regulate the amount and direction of exhaust flow through the exhaust treatment system based on whether storage or purge operation of the HC trap is desired, or whether EGR operation is desired. One or more exhaust valves can be integrated such that ...

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Problems solved by technology

Restricted flow characteristics can also affect the efficiency of exhaust treatment systems, reducing the quality of exhaust emissions

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