Patent ID: 6941913

Claim:
A variable cam timing phaser for an internal combustion engine with at least one camshaft comprising: a housing having 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; the rotor further having an axial cylindrical bore comprising an open outer end, an inner surface, and an inner end having a vent port, and arranged along the bore, an advance port in fluid communication with the advance chamber, a common port, a retard port in fluid communication with the retard chamber, and a lock port in fluid communications with a lock pin bore; a spool valve comprising a spool slidably located within the bore in the rotor, the spool comprising, in order from an outer end to an inner end, a first land, a first groove, a second land, a second groove, and a third land; the area within the bore between the inner surface of the bore and the first groove defining a first chamber, the area between the inner surface of the bore and the second groove defining a second chamber and the area between the inner surface of the bore and the inner end of the spool defining a third chamber; the spool having a passage from the first groove to the second groove for fluid passage between the first chamber and the second chamber; wherein when the spool is in an outermost position closest to the outer end of the bore, one of the retard port or the advance port is blocked by the second land, the first chamber is in communication with the other of the advance port or the retard port and the common port, and the lock port is in fluid communication with the third chamber and the vent port, such that the lock pin is in a locked position; wherein when the spool is in a null position, the advance port and the retard port are blocked by the first land and the second land, and the lock port is in fluid communication with the second chamber, such that the lock pin is in an unlocked position; and wherein when the spool is in an innermost position closest to the inner end of the bore, one of the retard port or the advance port is blocked by the first land, the first chamber is in communication with the other of the advance port or the retard port and the common port, and the lock port is in fluid communication with the second chamber, such that the lock pin is in an unlocked position.