Lin Engineering, Inc.

Other

Linex Technology, Inc.

Ted T Lin

Ryan C Lin

Richard L Badgerow

Harlan H Nguyen

Guangming Peng

Wayne C Lockhart

JianJun Gan

Nicholas A Vergara

Abdallah Samaha

A two-phase bipolar step motor, comprises a rotor having a plurality of pairs of rotor poles of alternating magnetic polarity, and a stator having four primary energizable stator poles with conductive windings around those primary stator poles and four passive inter-poles located uniformly between every adjacent pair of primary stator poles, the passive inter-poles lacking any conductive windings. Both 18° steppers with five pairs of rotor poles and 30° steppers with three pairs of rotor poles are provided. Also provided are both PM hybrid mix steppers with 2D magnetic flux paths and hybrid steppers with 3D magnetic flux paths having an axial component. In each case, the overall lengths of the flux paths are substantially reduced from conventional designs resulting in improved motor efficiency.

4-stator-pole step motor with passive inter-poles

A 2-phase bipolar step motor has a rotor and a stator, the rotor having a plurality of equally spaced rotor poles of alternating north and south magnetic polarities, and the stator having at least eight stator poles extending radially from a stator yoke and terminating in pole shoes interacting radially across an air gap with the rotor poles to cause the rotor to rotate step-by-step when windings around the stator poles are driven by a succession of energized states of the stator. The stator poles divided into four equal groups having a specified drive phase A or B, adjacent poles of a group having alternating drive polarities of the same drive phase A and &#x100;, or B and. Adjacent poles in the same group are separated by a center-to-center angle one-half of the rotor tooth pitch or up to 20% larger. Adjacent poles of different groups have a larger separation than that between poles of the same group.

Step motor with spacing of same-phase stator pole groups based on one-half rotor tooth pitch

A two-phase bipolar step motor, comprises a rotor having a plurality of pairs of rotor poles of alternating magnetic polarity, and a stator having four primary energizable stator poles with conductive windings around those primary stator poles and four passive inter-poles located uniformly between every adjacent pair of primary stator poles, the passive inter-poles lacking any conductive windings. Both 18&#xb0; steppers with five pairs of rotor poles and 30&#xb0; steppers with three pairs of rotor poles are provided. Also provided are both PM hybrid mix steppers with 2D magnetic flux paths and hybrid steppers with 3D magnetic flux paths having an axial component. In each case, the overall lengths of the flux paths are substantially reduced from conventional designs resulting in improved motor efficiency.

A variable reluctance stepper motor comprises a stator and a rotor that is rotatable relative to the stator. The stator comprises an annular outer yoke with a set of circumferentially spaced stator poles at equal angular intervals around the yoke extending radially inward from first portions of the yoke toward the rotor. Phase windings are individually coiled around each of the respective stator poles. Multiple slots are formed in an outer perimeter edge of the yoke at second portions thereof circumferentially situated between the first portions. A permanent magnet is embedded within each slot with circumferentially directed magnetic orientation of the respective permanent magnets. The remote placement of the magnets ensure that detent torque is kept to a minimum, while also increasing holding and dynamic torque levels.

Variable reluctance step motor having enhanced holding torque

A step motor that provides reduced detent torque while maintaining adequate holding torque is characterized by a rotor that includes an annular ring of soft magnetic material (such as medium carbon steel) that surrounds the outer diameter of the rotor permanent magnet and is sandwiched by magnetic insulators of specified axial thickness. This provides a path within the rotor for flux from the permanent magnet in those areas where the radially adjacent stator poles are unenergized, but the magnetic flux can be pulled out by the ampere-turns of energized stator poles.

Low detent torque hybrid step motor

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

Step motors have a uniformed 8-stator pole design, while maintaining the number of stator teeth very close to the number of rotor teeth for better torque. A two-phase bipolar stepper includes an 8-pole stator with a plurality of stator teeth uniformly arranged on each pole. If D is the nominal inner diameter of the stator expressed in millimeters, a number of stator teeth per pole equal to D&#xf7;3 (rounded to the nearest integer) will accommodate the required winding needle space between adjacent stator poles. The step motor also has a rotor mounted for rotation within the stator with a plurality of rotor teeth. The respective numbers of rotor and stator teeth may differ at most by two or have a tooth ratio greater than 95%. The teeth should have minimum tooth width and separation of at least 0.5 mm for adequate contrasting magnetic definition (polarity and/or flux amplitude) in the rotor-stator interaction.

8-pole, 2-phase bipolar step motors with easy manufacture and optimum torque for size

A nut driven by a lead screw and stepper motor has an internal concave recess for holding high viscosity grease that is semi-solid at ambient temperature and spaced from the lead screw. Grease flow ensues with lead screw motion causing a slow flow of grease coating the lead screw with a thin coating of grease as the nut travels back and forth over the lead screw. The nut may be an anti-backlash nut or a single member nut with both having a concave recess about the lead screw for the grease.

Lubrication reservoir for lead screw assembly

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.

Reduced-vibration stepper motor

A step motor integrates its mounting face and heat sink into the stator design. In particular, mounting holes (typically, four in number) are provided through the stator stack in outer perimeter areas. The stator stack itself becomes the mounting surface, allowing the heat generated from the stator to conduct directly to the mounting plate. The front end cap for holding the rotor in alignment is situated inside of the stator's mounting surface and takes no part in mounting the motor to the mounting surface. The end caps only hold the rotor in proper relation within the stator and contain the bearing assembly for the rotor's axial drive shaft. The perimeter of the stator assembly between the mounting screw holes may have saw-tooth cutouts that define heat-dissipation fins.

Motor having stator assembly with integrated mounting and heat sink features

A stepper motor is provided in which a permanent ring magnet is sandwiched in an outer part of the stator winding assembly located far from the gap between rotor and stator teeth, so that magnetic flux in the gap is dominated by the Ampere-turns of energized stator coils and therefore more easily controlled for reduced vibration at low stepping speeds. The rotor need not contain any permanent disk magnet. If one is provided, it can be completely embedded within the rotor and merely supplement the primary flux from the stator to enhance torque. In most cases, where the rotor lacks any permanent magnet, the motor's axial shaft can have a larger diameter and may, together with the rotor, form a linear actuator.

Hybrid step motor

A rotary machine (e.g., motor or generator) has end caps with plastic piloting rings that engage a stator's plastic winding frame in an interference fit, so that a rotor seated by bearings in the end caps is properly aligned with the stator. The flexibility of the plastic-to-plastic fit allows looser tolerances in comparison to machining of all-metal end caps, while the average circle of the piloting ring's outer diameter still assures proper concentricity of rotor shaft, bearings, piloting rings and stator.

Motor end cap with interference fit

A motor is provided with a set of end cap guides on the ends of a stator winding assembly to pilot the placement of end caps into the correct placement relative to the stator winding assembly so that the rotor assembly is maintained concentric with the stator. The end cap guides may be rings fitting within the winding insulators on the ends of the stator stack or may be integrated as guide segments with the winding insulators to outline an interrupted cylindrical inner surface coinciding with the inner diameter of the stator winding assembly. The guides allow proper positioning of the rotor assembly without increasing the stator stack length.

Motor end cap positioning element for maintaining rotor-stator concentricity

A belt and roller system comprising a roller having a permanent magnet sandwiched in between a pair of temporarily magnetic disks with the magnetism of the disks induced by the permanent magnet. Each temporarily magnetic disk may be steel. Each pole of the permanent magnet is disposed adjacent to a pole of one of the temporarily magnetic disks resulting in a magnetic attraction to a disk at each pole of the permanent magnet. The opposing magnetic poles of the disks form a magnetic flux circuit by which a temporarily magnetic belt, such as a steel belt is guidable to prevent or reduce deviation which it may have from its roller path. Additional permanent magnetic rollers or other rollers known in the art may be combined with the magnetic roller of the present invention to form a gear train about which the belt rotates.

Magnetic belt and roller system

A hybrid step motor has axially spaced first and second sets of rotor sections (or alternatively different sets of stator sections) characterized by different tooth widths. The rotor/stator tooth width ratio in one set is optimized for one-phase ON operation while the rotor/stator tooth width ratio for the other set is optimized for two-phase ON operation. More generally, the two sets are optimized together for near sinusoidal, torque profile and substantially equal microsteps.

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Saratoga, CA, United States of America

Ted T Lin