Method and system for engine cold start and hot start control

摘要

Methods and systems are provided for controlling exhaust emissions by adjusting an injection profile for fuel injected into an engine cylinder from a plurality of fuel injectors during engine start and crank. By splitting injection of fuel during start so that a portion of fuel is port injected and a remaining portion is direct injected as one or multiple injections, the soot load of the engine can be reduced and fuel economy can be improved.

主权项

1. A method of operating an engine, comprising,
responsive to an engine cold-start and during a first combustion event since the engine cold-start:
port injecting a first portion of fuel during a closed intake valve event; anddirect injecting a remaining portion of the fuel over multiple injections of the first combustion event at a first ratio of the first port injection portion relative to a total first direct injection amount; and responsive to an engine hot-start and during a first combustion event since the engine hot-start:
port injecting a second portion of fuel;direct injecting a remaining portion of the fuel over multiple injections of the first combustion event at a second ratio, higher than the first ratio, of the second port injection portion relative to a total second direct injection amount; andwherein a first direct injection ratio of intake to compression injection during the cold-start is higher than a second direct injection ratio of intake to compression injection during the hot-start.