Lin Engineering, Inc.

Harlan H Nguyen

Ted T Lin

Hung H Pham

Nicholas A Vergara

Hoang H Le

A captive leadscrew-type linear actuator assembly has a motor whose rotor has a rearward extending hollow bore shaft. An external nut assembly fixed to the bore shaft to rotate with rotor engages a lead screw. An anti-rotation radial support plate attaches to a front of the motor with a non-circular hole that prevents rotation of a rod or piston attached to the lead screw. Accordingly, torque applied by the rotor through the nut to the lead screw is converted into linear motion wherein the rod or piston passes through the hole. Replaceable external components lead to greater design flexibility together with improved motion accuracy and durability.

Linear captive motor-leadscrew assembly

A radial-type anti-backlash nut for use upon linear actuator leadscrews uses a separate housing resting upon the actuator's main nut. The anti-backlash action is a multi-finger collet and spring setup located inside the housing. The collet tapers radially inward toward tips of the fingers at a specified taper angle. The whole interior length of an internal thread of the collet engages an external thread of the leadscrew. The housing is a pre-load nut with an internal tapered surface that mates with the collet fingers with substantially the same taper angle. The pre-load nut, when screwed onto external threads of the adjustment nut, both compresses a load spring and applies radially inward adjustable load force to the collet fingers against the leadscrew. Three tolerances adjust load: the taper angle of the main nut's collet fingers, the spring load's compression, and the collet finger mismatch with respect to the lead screw.

Anti-backlash mechanism for electromechanical linear actuator

A step motor comprises both a rotor and a stator winding assembly. The rotor has a plurality Nr of rotor teeth. The rotor fits within the stator winding assembly and is seated by bearings on an axial shaft to rotate within the stator winding assembly. The stator winding assembly includes a stator with a plurality of stator poles and is wound with coils that can be driven in a series of phases to magnetically interact with the rotor. Each stator pole has a plurality of stator teeth. The total number Ns of stator teeth on all poles of the stator is equal to or greater than the number of rotor teeth (Ns&#x2265;Nr) to deliver more torque. Various embodiments of two-phase, three-phase and five-phase bipolar step motors having 8, 9 and 10 stator poles, respectively, and different numbers of teeth are provided, including two embodiments with nonuniform stators.

Hybrid step motor with greater number of stator teeth than rotor teeth to deliver more torque

A stepper motor has a stator winding assembly with a permanent ring magnet located radially outside of electromagnetic windings for the stator poles. The permanent ring magnet remotely magnetizes a rotor seated by bearings on an axial shaft so as to rotate within the stator winding assembly, thereby freeing up space within the rotor for an internal damper. The rotor has a cylindrical damping weight enclosed within, but not fixed to, the rotor. The weight ideally has a rotational moment of inertia that substantially matches that of the rotor. The weight is elastically coupled to the rotor by a viscous material contained in the rotor and filling the space between the weight and the rotor and between the weight and the axial shaft. The viscosity of this material is selected such that motion of the weight is delayed, preferably so as to be substantially 180&#xb0; out-of-phase with, but at the same frequency as, the stepping rotation of the rotor. The weight thereby serves as a counterweight to the rotor so as to cancel vibrations generated by stepping of the rotor.

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San Jose, CA, United States of America

Harlan H Nguyen