In a feed unit of a rod-type actuating element that is arranged in a housing (2) and guided for axial displacement relative to the housing (2), the feed unit further being a drive motor (4) that effects the displacement of the actuating element through a driving device that is rotatably retained in bearings in the housing (2), said driving device being a threaded spindle (1) and a spindle nut (3) surrounding the threaded spindle, wherein the drive motor (4) with its stator (5) and rotor (6) is arranged in the housing (2), and the spindle nut (3) is coaxially arranged in and fixed to a hollow shaft (7) that is surrounded by and fixed to the rotor (6).
An electric actuator that is capable of driving a motor in a cylindrical structure, such that the electric actuator itself can be expanded. The electric actuator includes: a motor for driving the electric actuator and a screw cylinder for connecting a shaft of the motor to a connecting part and for surrounding the external surface of the motor. The screw cylinder has right-handed and left-handed screw recesses formed thereon, and has first and second ball screw nuts. The first ball screw nut has a first electronic brake mounted thereon and the second ball screw nut has a second electronic brake mounted thereon, thereby enabling a non-stop reciprocating linear movement. An outside cylinder is provided with thrust bearings that are in contact with the first and second ball screw nuts, and is provided with a sensor that is disposed on the surface of a fixed part thereof for measuring the movement distance of the screw cylinder, thereby enabling the first and second electronic brakes to control the operations of the first and second ball screw nuts.
