Abstract: 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 ?, or B and 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: A linear stepping motor has a linear stator and a rod movable longitudinally within the stator. The rod has alternating permanent magnets and spacer disks, successive magnets being N-S opposed. A rod pitch equals twice the magnet width plus twice the disk width. The stator has a stack of stator groups associated with the drive phases. Each stator group is a pair of stator poles of opposite magnetic polarity separated by one-half rod pitch. Adjacent poles in different groups are separated by a [(n+1)/2n] rod pitch, where n is the number of drive phases. Each pole may be an annular disk yoke with a plurality of inward projecting salient pole pieces terminating in pole shoes. Conductive windings for a stator group proceed successively around each pole piece in one direction for a first pole of the group and then successively in a reverse direction for a second pole of the group.

Abstract: 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 ?, or B and 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.

Abstract: A two-phase stepper motor with a permanent magnet (PM) rotor and a modified hybrid-type stator is provided. The modified hybrid stator can be manufactured even at the smaller motor size because it employs shoeless, straight stator poles without stator teeth and with bobbin coils that are pre-wound outside the motor and easily inserted over each of the stator poles. Each bobbin may be an elongated continuous belt of insulative material with a hollow interior that forms a sleeve that fits around its corresponding stator pole. Conductive wire wound around the sleeve forms the stator coils. Edges of the sleeve may have exterior flanges at radially inner and outer ends of the stator pole to hold windings in place and keep the sleeve from bowing outward. This stator construction allows the motor to be miniaturized so that the PM rotors can be 13 mm diameter or less.

Abstract: 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.

Abstract: A miniature step motor is constructed with a permanent magnet rotor and a hybrid stator assembly. The rotor, mounted for rotation on an axial shaft, has one or more rotor sections or pieces with a pair of magnetic poles on opposed circumferential surfaces of each piece. The stator assembly, with an inner diameter to receive the rotor, is formed from a stack of bipolar phase-stators positioned in different axial planes, each phase-stator interacting with a rotor section via a two-dimensional magnetic flux path that is independent of every other phase-stator in the stack. The at least one rotor section and the phase-stators have different amounts of 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.