| 摘要 |
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.
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