Patent ID: 8025036

Claim:
A valve timing control apparatus comprising: a driving rotation member synchronously rotating with a crankshaft of an internal combustion engine; a driven rotation member coaxially arranged with the driving rotation member and synchronously rotating with a camshaft for opening and closing a valve of the internal combustion engine; an advance angle chamber defined by the driving rotation member and the driven rotation member, the advance angle chamber displacing a rotation phase of the driven rotation member relative to the driving rotation member in an advance angle direction when the hydraulic fluid is supplied to the advance angle chamber; a retard angle chamber defined by the driving rotation member and the driven rotation member, the retard angle chamber displacing the rotation phase of the driven rotation member relative to the driving rotation member in a retard angle direction when the hydraulic fluid is supplied to the retard angle chamber; an advance angle oil passage through which the hydraulic fluid is supplied to or discharged from the advance angle chamber; a retard angle oil passage through which the hydraulic fluid is supplied to or discharged from the retard angle chamber; an oil pump supplying the hydraulic fluid to the advance angle oil passage and the retard angle oil passage; a passage switching valve switching a position thereof between a first position, in which an output portion of the oil pump communicates with the advance angle oil passage, and a second position, in which the output portion of the oil pump communicates with the retard angle oil passage; a retard angle oil passage drain mechanism between the retard angle chamber and the passage switching valve to release the hydraulic fluid in the retard angle oil passage to atmosphere between the retard angle chamber and the passage switching valve when the hydraulic fluid is supplied to the advance angle chamber through the advance angle oil passage by the oil pump; and an advance angle oil passage drain mechanism between the advance angle chamber and the passage switching valve to release the hydraulic fluid in the advance angle oil passage to atmosphere between the advance angle chamber and the passage switching valve when the hydraulic fluid is supplied to the retard angle chamber through the retard angle oil passage by the oil pump.