Patent ID: 7614372

Claim:
A spring assembly for rotationally biasing a rotor with respect to a stator in a camshaft phaser, comprising: a central spring arbor connected to said rotor; and a torsional spring surrounding said central spring arbor and having a plurality of helically-arranged coils including an innermost coil at an inner end thereof, an outermost coil at an outer end thereof, and at least one intermediate coil between said innermost coil and said outermost coil, said torsional spring having an inner radius; wherein one of said innermost and outermost coils is operationally connected to said rotor and the other of said innermost and outermost coils is operationally connected to said stator; wherein a first radius of said central spring arbor adjacent said at least one intermediate coil is less than said inner radius of said torsional spring; and wherein a second radius of said central spring arbor adjacent said innermost and outermost coils over an angular region thereof is greater than said first radius.