Patent ID: 6443113
Filing Date: 2002-09-03
Classification: F01L

Abstract:
A variable valve timing system comprising:a housing member rotatable as a unit with either a crankshaft or a camshaft of an internal combustion engine; a rotor member relatively rotatably assembled on a shoe portion of the housing member and forming an advanced angle chamber and a retarded angle chamber at a vane portion in the housing member, said rotor member rotating as a unit with either the crankshaft or the camshaft of the internal combustion engine; a relative rotation controlling mechanism allowing relative rotation of the housing member and the rotor member by an unlock operation through supply of an operation fluid, and restricting relative rotation of the housing member and the rotor member by a lock operation through discharge of the operation fluid at a lock phase within an intermediate area from a most advanced angle phase to a most retarded angle phase excluding rotation limited phases of both ends; a fluid pressure circuit for controlling the operation fluid to be supplied to and discharged from the advanced angle chamber, the retarded angle chamber, and the relative rotation controlling mechanism; the relative rotation controlling mechanism being formed with a first controlling mechanism restricting the relative rotation to an advanced angle side when the first controlling mechanism is operated under the lock operation at the lock phase, and a second controlling mechanism restricting the relative rotation to a retarded angle side when the second controlling mechanism is operated under the lock operation at the lock phase; the fluid pressure circuit supplying and discharging the operation fluid to or from the advanced angle chamber through the first controlling mechanism, and supplying and discharging the operation fluid to or from the retarded angle chamber through the second controlling mechanism; a first passage connecting the advanced angle chamber with the first controlling mechanism and functioning as a throttle; and a second passage connecting the retarded angle chamber with the second controlling mechanism and functioning as a throttle.