Patent ID: 8881881

Claim:
A viscous clutch comprising: an input member to accept input torque; a rotor secured to the input member to rotate therewith; an output member located adjacent to the rotor; a working chamber defined between the rotor and the output member; a reservoir configured to hold a shear fluid; a return path defined between the working chamber and the reservoir; an electromagnetic coil for selectively generating a magnetic field; and a valve assembly configured to selectively control shear fluid flow between the reservoir and the working chamber, the valve assembly comprising: an orifice plate defining a bore to allow the passage of the shear fluid through the orifice plate; a reed valve secured relative to the orifice plate, the reed valve including: a tongue portion configured to selectively cover the bore of the orifice plate; and a first pivot location along the tongue portion about which a distal end of the tongue portion can pivot; an armature comprising a magnetic flux-conducting material, the armature configured to selectively apply a force to the reed valve as a function of the magnetic field generated by the electromagnetic coil to pivot at least the distal end of the tongue portion about the first pivot location; an anchor spring secured to the armature; and a stiffening plate, wherein a second pivot location is defined along the anchor spring at an edge of the stiffening plate, and wherein the first and second pivot locations are spaced from each other.