Patent ID: 7363897

Claim:
In a camshaft phaser for advancing and retarding the timing of valves in an internal combustion engine, wherein the phaser includes a rotor having a rotational range of authority within a stator, a cover plate disposed over the rotor and stator, and lock pin means for locking the rotor to the stator at an intermediate rotor position in the range of authority, the improvement comprising a bias spring system operationally disposed between said rotor and said stator for urging said rotor toward said intermediate position from only a portion of said range of authority, wherein said bias spring system includes a torsion spring grounded via a first tang to said stator, an anchor plate for capturing said torsion spring against said cover plate, and a spring retainer coupled to said rotor and rotatable past said anchor plate and having a slot formed such that an end of said slot engages a second tang of said spring whenever said rotor is urged into a predetemined portion of said range of authority from said intermediate position.