A fast-acting rotor-locking mechanism for a vane-type camshaft phaser. A straight-sided
locking pin is disposed in a bushing in the rotor and is urged into a sprocket
well by a return spring. A pad disposed at the bottom of the well is a travel stop
for the pin. When the pin is fully seated against the pad, the pad covers a portion
of the end of the pin. The uncovered portion of the pin end, exposed to oil pressure
for unlocking the pin when it is fully seated, is decreased over the prior art
pin, permitting use of a lighter locking spring having a lower spring rate. Because
of the lighter locking spring, the pin accelerates more rapidly and unlocks significantly
faster than in a comparable prior art phaser.
