METHOD AND SYSTEM FOR CATALYST TEMPERATURE CONTROL

摘要

Methods and systems are provided for controlling and coordinating control of a post-catalyst exhaust throttle and an EGR valve to expedite catalyst heating. By closing both valves during an engine cold start, an elevated exhaust backpressure and increased heat rejection at an EGR cooler can be synergistically used to warm each of an engine and an exhaust catalyst. The valves may also be controlled to vary an amount of exhaust flowing through an exhaust venturi so as to meet engine vacuum needs while providing a desired amount of engine EGR.

主权项

1. A method for expediting activation of an exhaust catalyst coupled to an engine comprising:
during an engine cold-start, closing a post-catalyst exhaust throttle while diverting at least a portion of the throttled exhaust gas through an EGR cooler coupled upstream of the throttle.