Patent ID: 6925976
Filing Date: 2005-08-09
Classification: F01L,F02D

Abstract:
1. A variable valve actuation system for operating at least one exhaust valve of an internal combustion engine during a positive power operation and an engine braking operation, said system comprising: an exhaust rocker assembly for operating said at least one exhaust valve, said exhaust rocker assembly driven by an exhaust cam member; an exhaust hydraulic extension device operatively coupling said exhaust rocker assembly with one of said at least one exhaust valve and said exhaust cam member for controlling a lift and a phase angle of said at least one exhaust valve; a source of a pressurized hydraulic fluid in fluid communication with said exhaust hydraulic extension device; and an exhaust control valve provided to selectively supply the pressurized hydraulic fluid from said source to said exhaust hydraulic extension device so as to switch said exhaust hydraulic extension device between a pressurized condition when the pressurized hydraulic fluid is supplied to said exhaust hydraulic extension device and a depressurized condition when the pressurized hydraulic fluid is not supplied to said exhaust hydraulic extension device; said engine having an exhaust brake provided to generate an exhaust backpressure sufficient to cause said at least one exhaust valve to open near a bottom dead center of an intake stroke of the engine during the engine braking operation; said exhaust hydraulic extension device in said pressurized condition provided to maintain said at least one exhaust valve open during a compression stroke when said engine performs the engine braking operation.