Patent ID: 6505586
Filing Date: 2003-01-14
Classification: F01L,F02D,Y02T,Y10T

Abstract:
A variable valve timing control apparatus for an internal combustion engine, said apparatus comprising:a first rotary body, which rotates in synchronism with a crankshaft of the internal combustion engine; a second rotary body which is concentric with the first rotary body and is linked to a camshaft for opening/closing an engine valve; a vane attached to either the first rotary body or the secondary rotary body to divide a fluid chamber formed between the rotary bodies into an advancing chamber and a retarding chamber; fluid pressure control means for controlling the pressure of fluid supplied to the advancing chamber and retarding chamber; valve timing control means for variably controlling valve timing of the engine by changing the phase of the camshaft with respect to the crankshaft by relatively turning the first rotary body and the secondary rotary body; lock means for locking the camshaft phase at an intermediate lock phase within its controllable range when the internal combustion engine is stopped or when cranking the engine; an unlocking chamber to which fluid pressure for unlocking the camshaft phase of the lock means is supplied; and unlock control means for positively preventing fluid pressure within the unlocking chamber from increasing when cranking the engine, wherein the unlocking chamber is communicated with the retarding chamber and is supplied with fluid pressure from the retarding chamber; and the unlock control means controls the fluid pressure control means so that the fluid pressure is supplied only to the advancing chamber in cranking the engine.