Method and system for engine control

摘要

Methods and systems are provided for extending an engine-off period of a hybrid vehicle while reducing engine cold-start emissions. During an engine pull-up to meet operator demand, the engine is held at a higher power for a longer duration to aggressively heat the exhaust catalyst. Subsequently, the engine is pulled up to a lower power and held at the lower power for shorter bursts of time to activate the exhaust catalyst.

主权项

1. A method for a vehicle, comprising:
within a single vehicle drive cycle, initially pulling up an engine to, and holding at, a higher power in response to operator torque demand; subsequently pulling up the engine to, and holding at, a lower power in response to catalyst temperature; and while initially pulling up the engine, indicating a first engine cold-start on a counter, and incrementing the counter while subsequently pulling up the engine, the counter reset in response to an operator vehicle key-off event.