Patent ID: 7219636
Filing Date: 2007-05-22
Classification: F01L

Abstract:
1. A variable valve timing control system of an internal combustion engine comprising: a rotary member adapted to be driven in synchronization with rotation of an engine crankshaft, and rotatably supported on a camshaft to permit relative rotation of the camshaft to the rotary member; a hydraulically-operated phase converter disposed between the rotary member and the camshaft, and having a phase-advance hydraulic chamber and a phase-retard hydraulic chamber for changing an angular phase of the camshaft relative to the rotary member; an electric pump that supplies working fluid to the phase-advance hydraulic chamber and the phase-retard hydraulic chamber through a phase-advance hydraulic line connected to the phase-advance hydraulic chamber and a phase-retard hydraulic line connected to the phase-retard hydraulic chamber; a directional control valve disposed between a first pair of fluid lines including a discharge line and an induction line of the pump and a second pair of fluid lines including the phase-advance hydraulic line and the phase-retard hydraulic line, for determining a path through which the working fluid is directed from the discharge line to a first one of the phase-advance hydraulic line and the phase-retard hydraulic line and simultaneously determining a path through which the working fluid is directed from the second one of the phase-advance hydraulic line and the phase-retard hydraulic line to the induction line; a control unit configured to be electronically connected to at least the directional control valve, for controlling the directional control valve depending on an engine operating condition; a check valve disposed in the discharge line for permitting flow in a direction that the working fluid flows from the pump to the directional control valve and preventing any flow in the opposite direction; and a supplementary pump operable independently of the electric pump for supplying moving engine parts with working fluid for lubrication and supplying the working fluid through a working-fluid passage to the phase-advance hydraulic chamber and the phase-retard hydraulic chamber of the phase converter, wherein the phase converter comprises an air bleeder for forcibly exhausting air mixed in the working fluid in the phase converter to an exterior space by supplying the working fluid pressurized by the supplementary pump to the phase-advance hydraulic chamber and the phase-retard hydraulic chamber of the phase converter.