METHOD AND SYSTEM FOR VACUUM 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 an engine, comprising:
while recirculating an amount of exhaust gas to an engine intake, closing a post-catalyst exhaust throttle to increase vacuum generation at an exhaust ejector; and closing an EGR valve to maintain the amount of exhaust gas recirculation.