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Engine including hydraulically actuated valvetrain and method of valve overlap control

United States Patent

8,171,900
May 8, 2012
View the Complete Patent at the US Patent & Trademark Office
An exhaust valve control method may include displacing an exhaust valve in communication with the combustion chamber of an engine to an open position using a hydraulic exhaust valve actuation system and returning the exhaust valve to a closed position using the hydraulic exhaust valve actuation assembly. During closing, the exhaust valve may be displaced for a first duration from the open position to an intermediate closing position at a first velocity by operating the hydraulic exhaust valve actuation assembly in a first mode. The exhaust valve may be displaced for a second duration greater than the first duration from the intermediate closing position to a fully closed position at a second velocity at least eighty percent less than the first velocity by operating the hydraulic exhaust valve actuation assembly in a second mode.
Cowgill; Joel (White Lake, MI)
GM Global Technology Operations LLC (
12/ 685,061
January 11, 2010
GOVERNMENT LICENSE RIGHTS The Government of the United States of America has rights in this invention pursuant to Contract No. DE-FC26-05NT42415 awarded by the United States Department of Energy.