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 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 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.

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 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.

Abstract: A stepper motor has electromagnetically driven stator segments facing corresponding rotor segments. In order to reduce vibration of the stator segments, motor body end caps are provided with a stepped annular rim along an inside diameter of a centering sleeve. The stepped rim bears against each axial end of the stator segments, with a radial dimension and an axial dimension bracketing a stator segment end in place.

Abstract: A step motor having a stator constructed with six teeth per pole is achieved for a stator inner diameter (ID) less than one inch (25.4 mm) by a either (1) reducing the pitch angle of the outer teeth of each pole (e.g., to at most 6.8 degrees for a 19 mm stator ID), or (2) narrowing the tooth width of those outer teeth (e.g., to at most 0.0175 inch or 0.444 mm for a 19 mm stator ID), or (3) combination of both. These changes allow sufficient space (i.e., wider than 0.052 inch or 1.321 mm) between poles for passage of a winding needle, even with the extra stator teeth. Although narrowing the pitch angle and reducing the tooth width do sacrifice some torque contribution from each tooth, there still results a net overall gain in torque.

Abstract: 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.

Abstract: 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.

Abstract: A two-phase permanent magnet step motor comprises a permanent magnet rotor having an equal number Nr of magnetic north and south poles defining a fundamental step angle ?=90°/Nr, such that a number of steps per revolution of the rotor is 360°/?, and a toothless hybrid stator with windings defining a number Ns of stator poles, with Ns being divisible by four and a ratio Nr/Ns=n/4, n being an odd integer. The permanent magnet rotor may comprise a set of rare-earth magnets. Preferably, Nr is at most 10 (i.e., not more than 20 rotor poles). A method of driving the step motor continuously applies successive current phases to the windings with the motor speed being controllable simply by the step pulse rate. The motor can be micro-stepped at low speeds for smooth operation.

Abstract: 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.

Abstract: A drive circuit for step motors with bifilar windings is provided in which both parallel and series winding configurations for the stator coils are selectable by a motor controller based on the motor speed. For low speeds a series configuration is selected, while for higher speeds a parallel configuration is selected. Dynamic torque is optimized by the selection for more efficient motor operation with less drive current.

Abstract: A motor is provided with a set of end cap guides on the ends of a stator winding assembly to plot 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.

Abstract: 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.

Abstract: 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.

Abstract: Systems and methods are disclosed for the remote design of an electric motor (e.g. an AC or DC motor) by a customer through an interactive Web-based process. A typical system includes a Web server capable of delivering an interactive web page to a remote system. The web page includes one or more input fields allowing a user to specify motion performance requirement values applied to a design algorithm. The user may specify only some of the possible performance values. The design algorithm generates electric motor design parameters which will achieve the desired performance values. The algorithm also performs a parametric search through an existing parts database for at least some existing components which can be used in the electric motor design. The electric motor performance data is presented as an output to the user.

Abstract: 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.