Method and system for vacuum generation

摘要

Methods and systems are provided for improving the vacuum generation efficiency of an ejector coupled to in an engine system. Vacuum is generated at the ejector at a faster rate but to a lower level by opening a throttle upstream of the ejector. Vacuum is then raised to a higher level but at a slower rate by closing the throttle upstream of the ejector.

主权项

1. A method for an engine, comprising:
opening a throttle upstream of an ejector coupled to an intake manifold to increase a rate of vacuum generation by the ejector during a first mode of operation; and closing the throttle upstream of the ejector to increase a level of vacuum generation by the ejector during a second mode of operation, the opening and closing of the throttle based on a desired vacuum level in a vacuum reservoir.