One-way directional control means for synchronous a.c. motors

Claim 1

A synchronous permanent magnet A.C. motor having stator means with abutment means, and rotor means comprising a rotor shaft mounted for rotation on the central axis of said stator means; a cam fixed on said shaft and having a radially extending leg portion projecting outwardly from the shaft; a permanent magnet rotor member mounted on and rotatable relative to said shaft; an elongated stop member pivotably mounted between its ends on said rotor member for pivotal movement about an axis parallel to said central axis; said stop member being movable on its pivot between a retracted position which permits the rotor member to freely rotate and an extended position in which an end of the stop member engages said abutment means, thereby preventing said rotor member from rotating; said stop member engaging the leg portion of said cam upon rotation of said rotor in an undesired direction to position the stop member to its extended position, and engaging the leg portion of said cam upon rotation of the rotor in a desired direction to position the stop member to its retracted position; said cam including a second portion which together with said leg portion engages said stop member on both sides of its pivot when said rotor is rotating in the desired direction thereby retaining the stop member in its retracted position and interlocking said rotor member and shaft for rotation in unison.