Crash stop shock ring for the protection of disk drive motor bearings

Abstract

A technique for preventing damage to ball bearings in a small form factor device where the drive motor has at least one crash stop ring disposed about the shaft and inside the rotor of the motor. The crash stop ring is dimensioned to permit only a small amount of movement of the rotor relative to the shaft. The permitted movement must be less than the minimum movement which would cause damage to the elements of the ball bearing. In an alternative embodiment, a rotor includes a flange extending in the radial direction from the rotor. A piezoelectric ring is rigidly mounted on both sides of the flange to engage one of the planar surfaces of the flange when the piezoelectric ring is in the relaxed state. With two such crash stop rings disposed so that the rings can engage both planar surfaces of the flange, the rotor is effectively clamped between the two piezoelectric crash stop rings whenever the piezoelectric crash stop ting is disconnected from the power source used to contract the piezoelectric material in a direction parallel to the axis of rotation of the rotor.