Patent ID: 7124722

Claim:
A variable cam timing system for an internal combustion engine comprising: a housing with an outer circumference for accepting drive force; a rotor for connection to a camshaft coaxially located within the housing, the housing and the rotor defining at least one vane separating a chamber in the housing into an advance chamber and a retard chamber, the vane being capable of rotation to shift the relative angular position of the housing and the rotor; a locking pin slidably located in a bore in one of the rotor or the housing, comprising a body having a diameter adapted to a fluid-tight fit in the bore, and an inner end with a portion adapted to fit in a recess in the other of the rotor or the housing the locking pin being moveable in the bore from a locked position to an unlocked position, the locking pin being released by pressure supplied from one of either the advance or retard chamber; a spool valve comprising a spool slidably located in a bore with a plurality of ports, the spool comprising a plurality of lands that block the ports; such that in a retard position, the plurality of lands allow fluid through the ports from the advance chamber to the retard chamber; such that in an advance position, the plurality of lands allow fluid through the ports from the retard chamber to the advance chamber; such that in a null position, the plurality of lands allow fluid from a source to the advance chamber and the retard chamber; and such that in a locked position, the plurality of lands allow fluid supplied to one of the advance chamber or the retard chamber to move the locking pin to a locked position and fluid from the other advance chamber or retard chamber to be vented.