| 摘要 |
An actuator, including an electric motor ( 14 ) having a stator ( 16 ) and a rotor ( 17 ), in which the rotor ( 17 ) defines a bearing surface ( 20 ) having a non-circular profile, and a radially flexible annular sleeve ( 24 ) defines a facing bearing surface. The flexible sleeve ( 24 ) adopts a non-circular shape complementary to the profile of the bearing surface ( 20 ). The flexible sleeve ( 24 ) is restrained against rotation and is in toothed meshing engagement with a circular drive ring ( 26 ) at least two contact regions which are equidistantly spaced apart. The drive ring ( 26 ) is rotationally engaged with a screw and threaded sleeve assembly, such that rotation of the drive ring ( 26 ) drives the screw and sleeve assembly and causes extension or withdrawal of an output portion ( 28 ) of the screw and sleeve assembly for actuation. The actuator is operable such that rotation of the rotor ( 17 ) causes the flexible sleeve ( 24 ) to flex radially at each of the contact regions to generate a rolling wave which causes rotation of the contact regions and of the drive ring ( 26 ), and the drive ring ( 26 ) rotates at a reduced rotational velocity as compared to the rotational velocity of the rotor ( 17 ).
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