Motorized anti-backlash linear actuator

Claim 1

Motorized anti-backlash linear actuator comprising, in combination: a source of rotary motion comprising a motor; a hollow armature in the motor mounted for rotation about a central axis; the armature surrounding a hollow shaft and secured directly thereto to rotate the shaft about the axis; the hollow shaft being one piece, inwardly threaded along its entire length and extending the entire length of the armature; frame means mounting the motor for internal rotational movement only at a fixed location in space and preventing its movement lengthwise of the axis; an externally threaded non-rotating rod extendable from and movable linearly along the axis relative to the fixed location of the motor; a continuously operating, rotatable anti-backlash nut assembly to produce substantially backlash-free linear motion of the rod lengthwise of the axis, the nut assembly comprising the hollow shaft within the armature and a cooperating spring means outside the motor; the threads of the hollow shaft and the rod being in direct physical contact; a field coil surrounding the armature to impart rotary motion to the unit; the anti-backlash nut assembly being secured to the hollow shaft such that the armature, the shaft and the anti-backlash nut assembly rotate as a unit at the fixed location in space while prevented by the frame from moving linearly; thereby to impart to the rod non-rotating linear motion lengthwise of the axis relative to the fixed location in space and which motion is substantially backlash-free.