Ejector in conjunction with post-catalyst exhaust throttle for vacuum generation

摘要

Methods and systems are provided for expediting catalyst heating and generating vacuum by controlling an EBV to direct exhaust through an ejector arranged in parallel with the EBV. A position of the EBV may be controlled to achieve a desired exhaust backpressure for current engine operating conditions and stored vacuum level. Compensation for the effect of EBV position on engine airflow may be provided by adjustment of other parameters such as intake throttle position and spark timing.

主权项

1. A method for generating vacuum from post-catalyst engine exhaust, comprising:
flowing engine exhaust gas through an exhaust passage to a catalyst positioned in the exhaust passage downstream of an engine; and flowing exhaust gas through the exhaust passage from the catalyst to an exhaust backpressure valve (EBV) and an ejector, each positioned in the exhaust passage downstream of the catalyst and in parallel with each other.