A rotary actuator (16) includes a rotor (48) which is disposed in a housing (34) between first and second pole pieces (42 and 44) of a stator (40). The rotor (48) is rotatable relative to the stator (40) between an unactuated position (FIG. 4) and an actuated position (FIG. 5). During rotation of the rotor (48), the axial extent of a first working air gap (66) between the rotor and a first pole piece (44) of the stator (40) remains constant. However, the axial extent of the working air gap (64) between the rotor (48) and the second pole piece (42) of the stator (40) decreases as the rotor moves from the unactuated position to the actuated position. In a preferred embodiment, the rotor lobes are made so that the net axial force of all of the rotor lobes is substantially zero thereby reducing stress on the rotor shaft support bearings.
CROSS-REFERENCES TO RELATED APPLICATIONS
The present invention is a continuation-in-part of "Rotary Actuator" U.S. application Ser. No. 09/660,142 filed Sep. 13, 2000, the entire contents of which is herein incorporated by reference.
A pin lock is movably mounted for linear movement along a longitudinal axis. A magnet, preferably a permanent magnet, is mounted for limited rotation between the pin extended and pin retracted positions. An electromagnet provides a controllable electromagnetic field which encompasses at least a portion of the permanent magnet. A ferromagnetic latch is located within the magnetic field of the mounted magnet in each of the pin extended and pin retracted positions. A mechanical interconnection between the pin lock and the permanent magnet for moving the pin lock when the permanent magnet is rotated wherein the movement extends or retracts the pin lock between its pin extended and pin retracted positions. Reversing the electromagnetic field of the electromagnet serves to rotate the magnet so that the pin lock moves from one to the other of the two positions.
