A magnetic pin insertion system comprises a rotary drive of a workpiece (rotor or stator) that a set of axially oriented slots around a circumferential surface that are receptive of magnetic pins. A cartridge holds an axially oriented stack of magnetic pins in guide chutes for each axial section of the workpiece. A pre-loaded feed mechanism (a weight or push spring) pushes the pins into successive slots of the workpiece as the rotary drive rotates the workpiece. Each cartridge chute terminates in an adjustable tongue, with a specified gap from the workpiece, that provides a resistive surface for shearing each pin away from other pins in the stack as they are pushed into their successive slots.
H02K 15/03 - Procédés ou appareils spécialement adaptés à la fabrication, l'assemblage, l'entretien ou la réparation des machines dynamo-électriques des corps statoriques ou rotoriques comportant des aimants permanents
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.
09 - Appareils et instruments scientifiques et électriques
Produits et services
Motors, namely rotary stepper motors, DC motors and servo motors, all not for land vehicles; wire harnesses, electrical cable, vibration reducing dampers for use with rotary stepper motors all not for land vehicles; gearboxes for use with motors not for land vehicles Electronic controllers for servo motors; electrical linear actuator steppers;
7.
Eight-stator-pole, bipolar, 3.6-° hybrid step motor
A two-phase bipolar 3.6° step motor is described in which the stator winding assembly has eight stator poles organized into decoupled phase groups with two distinct angular pole separations, 14.4°×[(4n±1)/4] between poles of the same group, and 14.4°×[(4m±1)/2] between adjacent poles of different groups, where n and m are positive whole numbers. Three stator teeth on each stator pole have a stator tooth pitch of 13.2° to minimize detent torque for smoother, more accurate stepping. A rotor has alternating magnetic north and south rotor teeth around a circumference thereof with a 14.4° rotor tooth pitch angle. The stator poles are wound with electromagnetic coil windings that can be driven in a series of phases to magnetically interact with the rotor.
H02K 37/04 - Moteurs à rotor tournant pas à pas et sans rupteur ou commutateur actionné par le rotor, p. ex. moteurs pas à pas du type à réluctance variable les rotors étant disposés à l'intérieur des stators
H02K 37/14 - Moteurs à rotor tournant pas à pas et sans rupteur ou commutateur actionné par le rotor, p. ex. moteurs pas à pas du type à aimant permanent avec des induits fixes et des aimants tournants avec des aimants tournant à l'intérieur des induits
8.
Anti-backlash mechanism for electromechanical linear actuator
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.
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.
H02K 37/14 - Moteurs à rotor tournant pas à pas et sans rupteur ou commutateur actionné par le rotor, p. ex. moteurs pas à pas du type à aimant permanent avec des induits fixes et des aimants tournants avec des aimants tournant à l'intérieur des induits
A two-phase bipolar step motor comprises a rotor (41) having a plurality of pairs of rotor poles (43) of alternating (N and S) magnetic polarity, and a stator (45) having four primary energizable stator poles (46-49) with conductive windings (55-58) around those primary stator poles and four passive inter-poles (467, 478, 489, 496) 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 (Figs. 4-9) and 30° steppers with three pairs of rotor poles (Figs. 10-15) are provided. Also provided are both PM hybrid mix steppers with 2D magnetic flux paths (Figs. 4-6, 10-12) and hybrid steppers with 3D magnetic flux paths having an axial component (Figs. 7-9, 13-15). In each case, the overall lengths of the flux paths are substantially reduced from conventional designs resulting in improved motor efficiency.
H02K 37/02 - Moteurs à rotor tournant pas à pas et sans rupteur ou commutateur actionné par le rotor, p. ex. moteurs pas à pas du type à réluctance variable
H02K 37/04 - Moteurs à rotor tournant pas à pas et sans rupteur ou commutateur actionné par le rotor, p. ex. moteurs pas à pas du type à réluctance variable les rotors étant disposés à l'intérieur des stators
H02K 37/10 - Moteurs à rotor tournant pas à pas et sans rupteur ou commutateur actionné par le rotor, p. ex. moteurs pas à pas du type à aimant permanent
H02K 37/14 - Moteurs à rotor tournant pas à pas et sans rupteur ou commutateur actionné par le rotor, p. ex. moteurs pas à pas du type à aimant permanent avec des induits fixes et des aimants tournants avec des aimants tournant à l'intérieur des induits
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.
H02K 37/14 - Moteurs à rotor tournant pas à pas et sans rupteur ou commutateur actionné par le rotor, p. ex. moteurs pas à pas du type à aimant permanent avec des induits fixes et des aimants tournants avec des aimants tournant à l'intérieur des induits
12.
Step motor with spacing of same-phase stator pole groups based on one-half rotor tooth pitch
B. 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.
H02K 37/14 - Moteurs à rotor tournant pas à pas et sans rupteur ou commutateur actionné par le rotor, p. ex. moteurs pas à pas du type à aimant permanent avec des induits fixes et des aimants tournants avec des aimants tournant à l'intérieur des induits
H02K 3/28 - Schémas d'enroulements ou de connexions entre enroulements
A two-phase stepper motor (91) with a permanent magnet (PM) rotor (41, 93) and a modified hybrid-type stator (61, 92) is provided. The modified hybrid stator can be manufactured for smaller motor sizes because it employs shoeless, straight stator poles (64) without stator teeth and with bobbin coils (71) that are prewound outside the motor and easily inserted over each of the stator poles. Each bobbin may be an elongated continuous belt (73) of insulative material with a hollow interior that forms a sleeve (75) that fits around its corresponding stator pole (64). Conductive wire (79) wound around the sleeve forms the stator coils. Edges of the sleeve may have exterior flanges (77, 78) at radially inner and outer ends of the stator pole to hold windings in place and keep the sleeve from bowing outward.
H02K 37/02 - Moteurs à rotor tournant pas à pas et sans rupteur ou commutateur actionné par le rotor, p. ex. moteurs pas à pas du type à réluctance variable
H02K 37/04 - Moteurs à rotor tournant pas à pas et sans rupteur ou commutateur actionné par le rotor, p. ex. moteurs pas à pas du type à réluctance variable les rotors étant disposés à l'intérieur des stators
H02K 37/08 - Moteurs à rotor tournant pas à pas et sans rupteur ou commutateur actionné par le rotor, p. ex. moteurs pas à pas du type à réluctance variable les rotors faisant axialement face aux stators
H02K 37/10 - Moteurs à rotor tournant pas à pas et sans rupteur ou commutateur actionné par le rotor, p. ex. moteurs pas à pas du type à aimant permanent
H02K 37/12 - Moteurs à rotor tournant pas à pas et sans rupteur ou commutateur actionné par le rotor, p. ex. moteurs pas à pas du type à aimant permanent avec des induits fixes et des aimants tournants
14.
VARIABLE RELUCTANCE STEP MOTOR HAVING ENHANCED HOLDING TORQUE
A variable reluctance stepper motor comprises a stator (11) and a rotor (41) that is rotatable relative to the stator. The stator comprises an annular outer yoke (20) with a set of circumferentially spaced stator poles (13) at equal angular intervals around the yoke extending radially inward from first portions of the yoke toward the rotor. Phase windings (31) are individually coiled around each of the respective stator poles. Multiple slots (17) are formed in an outer perimeter edge of the yoke at second portions thereof circumferentially situated between the first portions. A permanent magnet (19) is embedded within each slot with circumferentially directed magnetic (N-S) 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.
H02K 37/04 - Moteurs à rotor tournant pas à pas et sans rupteur ou commutateur actionné par le rotor, p. ex. moteurs pas à pas du type à réluctance variable les rotors étant disposés à l'intérieur des stators
H02K 19/24 - Génératrices synchrones avec des bobinages dont chaque spire est influencée alternativement par des pôles de polarités opposées, p. ex. génératrices hétéropolaires avec des rotors à réluctance variable, en fer doux, sans bobinage
H02K 29/03 - Moteurs ou génératrices à dispositifs de commutation non mécaniques, p. ex. tubes à décharge ou dispositifs à semi-conducteurs avec un circuit magnétique spécialement adapté pour éviter des ondulations du couple ou des problèmes de démarrage autonome
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.
H02K 37/04 - Moteurs à rotor tournant pas à pas et sans rupteur ou commutateur actionné par le rotor, p. ex. moteurs pas à pas du type à réluctance variable les rotors étant disposés à l'intérieur des stators
H02K 1/16 - Noyaux statoriques à encoches pour enroulements
H02K 37/14 - Moteurs à rotor tournant pas à pas et sans rupteur ou commutateur actionné par le rotor, p. ex. moteurs pas à pas du type à aimant permanent avec des induits fixes et des aimants tournants avec des aimants tournant à l'intérieur des induits
H02K 1/17 - Noyaux statoriques à aimants permanents
16.
MINIATURE STEP MOTOR WITH INDEPENDENT PHASE STATORS
A miniature step motor (11) has a permanent magnet rotor (13, 81, 91) and a hybrid stator assembly (15). The rotor has one or more rotor sections or pieces (13, 85-86, 95-97) with a pair of magnetic poles on opposed circumferential surfaces (23, 84, 94) of each piece. The stator assembly, with an inner diameter to receive the rotor, is formed from a stack of bipolar phase-stators (16A, 16B) positioned in different axial planes, each phase-stator interacting with a rotor section via a two-dimensional magnetic flux path independently of every other phase-stator in the stack. The rotor section (s) and the phase-stators have rotor-stator rotational offsets at specified angles 180°/N relative to each other about the axial shaft, where N is the number of motor phases. The phase-stators can be mutually offset from one another, or the rotor sections can be mutually offset.
H02K 37/04 - Moteurs à rotor tournant pas à pas et sans rupteur ou commutateur actionné par le rotor, p. ex. moteurs pas à pas du type à réluctance variable les rotors étant disposés à l'intérieur des stators
H02K 1/27 - Noyaux rotoriques à aimants permanents
17.
GEOMETRY FOR SINGLE-LAYER WOUND STATORS WITH HIGH MANUFACTURABILITY
An electric motor comprises a stator and a rotor having a specified number of rotor poles that magnetically interact with the stator so as to rotate in relation to the stator, The stator is a slotted stator with a specified number of stator poles with slots between those poles and is provided with a set of conductive windings that are fitted into the slots and wound around the stator poles according to a specified pattern. The motor has a single-layer winding configuration, wherein there are one or more empty stator poles without windings on each side adjacent to those stator poles with a winding, so that only one set of windings is present in each slot, Stator poles with a winding terminate in a stator shoe, while stator shoes are absent from each empty stator pole, thereby expanding the gap for machine winding into the slots.
H02K 3/28 - Schémas d'enroulements ou de connexions entre enroulements
H02K 3/46 - Fixation des enroulements sur la structure statorique ou rotorique
H02K 37/04 - Moteurs à rotor tournant pas à pas et sans rupteur ou commutateur actionné par le rotor, p. ex. moteurs pas à pas du type à réluctance variable les rotors étant disposés à l'intérieur des stators
H02K 3/04 - Enroulements caractérisés par la configuration, la forme ou le genre de construction du conducteur, p. ex. avec des conducteurs en barre
H02K 3/52 - Fixation des enroulements de pôles saillants ou de leurs connexions
H02K 3/12 - Enroulements caractérisés par la configuration, la forme ou le genre de construction du conducteur, p. ex. avec des conducteurs en barre disposés dans des encoches
H02K 37/00 - Moteurs à rotor tournant pas à pas et sans rupteur ou commutateur actionné par le rotor, p. ex. moteurs pas à pas
H02K 37/06 - Moteurs à rotor tournant pas à pas et sans rupteur ou commutateur actionné par le rotor, p. ex. moteurs pas à pas du type à réluctance variable les rotors étant disposés autour des stators
H02K 37/08 - Moteurs à rotor tournant pas à pas et sans rupteur ou commutateur actionné par le rotor, p. ex. moteurs pas à pas du type à réluctance variable les rotors faisant axialement face aux stators
H02K 37/18 - Moteurs à rotor tournant pas à pas et sans rupteur ou commutateur actionné par le rotor, p. ex. moteurs pas à pas du type à aimant permanent avec des induits fixes et des aimants tournants avec des aimants tournant à l'intérieur des induits du type homopolaire
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.
H02K 37/14 - Moteurs à rotor tournant pas à pas et sans rupteur ou commutateur actionné par le rotor, p. ex. moteurs pas à pas du type à aimant permanent avec des induits fixes et des aimants tournants avec des aimants tournant à l'intérieur des induits
H02K 1/04 - Détails du circuit magnétique caractérisés par le matériau employé pour l'isolation du circuit magnétique ou de parties de celui-ci
H02K 1/02 - Détails du circuit magnétique caractérisés par le matériau magnétique
19.
Hybrid step motor with greater number of stator teeth than rotor teeth to deliver more torque
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≥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.
H02K 37/04 - Moteurs à rotor tournant pas à pas et sans rupteur ou commutateur actionné par le rotor, p. ex. moteurs pas à pas du type à réluctance variable les rotors étant disposés à l'intérieur des stators
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° 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.
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÷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.
H02K 37/04 - Moteurs à rotor tournant pas à pas et sans rupteur ou commutateur actionné par le rotor, p. ex. moteurs pas à pas du type à réluctance variable les rotors étant disposés à l'intérieur des stators
H02K 37/18 - Moteurs à rotor tournant pas à pas et sans rupteur ou commutateur actionné par le rotor, p. ex. moteurs pas à pas du type à aimant permanent avec des induits fixes et des aimants tournants avec des aimants tournant à l'intérieur des induits du type homopolaire
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.
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.
H02K 1/20 - Parties fixes du circuit magnétique avec des canaux ou des conduits pour l'écoulement d'un agent de refroidissement
H02K 5/15 - Montage des flasques-paliers ou des plaques d'extrémité
H02K 5/18 - Enveloppes ou enceintes caractérisées par leur configuration, leur forme ou leur construction avec des nervures ou des ailettes pour améliorer la transmission de la chaleur
H02K 37/18 - Moteurs à rotor tournant pas à pas et sans rupteur ou commutateur actionné par le rotor, p. ex. moteurs pas à pas du type à aimant permanent avec des induits fixes et des aimants tournants avec des aimants tournant à l'intérieur des induits du type homopolaire
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.
H02K 37/00 - Moteurs à rotor tournant pas à pas et sans rupteur ou commutateur actionné par le rotor, p. ex. moteurs pas à pas
H02K 37/20 - Moteurs à rotor tournant pas à pas et sans rupteur ou commutateur actionné par le rotor, p. ex. moteurs pas à pas du type à aimant permanent avec des distributeurs de flux tournants, les induits et les aimants étant fixes
H02K 37/10 - Moteurs à rotor tournant pas à pas et sans rupteur ou commutateur actionné par le rotor, p. ex. moteurs pas à pas du type à aimant permanent
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.
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.
H02K 37/04 - Moteurs à rotor tournant pas à pas et sans rupteur ou commutateur actionné par le rotor, p. ex. moteurs pas à pas du type à réluctance variable les rotors étant disposés à l'intérieur des stators
28.
Laser welded step motor construction with compact end cap and stator lamination positioning
The method of providing a motor, includes providing a first thin-walled end cap having first inner and outer walls connected by a first integral side wall, the first outer wall defining a first terminal edge; providing a second thin-walled end cap having second inner and outer walls connected by a second integral side wall, the second outer wall defining a second terminal edge; providing a stator, having multiple parallel laminations defining an axially extending bore to receive a laminated rotor, the stator having end laminations, positioning the end caps so that the edges extend adjacent stator opposite end laminations.
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.
H02K 37/14 - Moteurs à rotor tournant pas à pas et sans rupteur ou commutateur actionné par le rotor, p. ex. moteurs pas à pas du type à aimant permanent avec des induits fixes et des aimants tournants avec des aimants tournant à l'intérieur des induits
A stepper motor includes a rotor having equally spaced rotor teeth defining a full step angle, and a stator with stator poles wound with coils that can be driven in a series of phases so as to magnetically interact with the rotor to produce stepping motion. The stator poles have teeth organized into two groups when there is an even number of stator teeth per pole, or into three groups for an odd number of stator teeth per pole. The stator teeth have an average pitch different from the rotor's tooth pitch, but the groups of stator teeth are also displaced relative to other groups by a specified offset angle of one-half or one-quarter step to double the number of detent positions, and to displace such detent positions from full one-phase ON or two-phase ON positions.
H02K 37/12 - Moteurs à rotor tournant pas à pas et sans rupteur ou commutateur actionné par le rotor, p. ex. moteurs pas à pas du type à aimant permanent avec des induits fixes et des aimants tournants
