Tri-tech Corporation

North American Philips Corporation

Haydon Switch & Instrument, Inc.

Charles W Hansen

Roy Cooper

Albert Palmero

Elmer W Madsen

A multi-phase stepper motor having an annular permanent magnetic rotor and a plurality of matingly engageable stator phase assemblies around the rotor. Each of the phase assemblies comprises a pair of annular pole pieces including interleaved salient stator poles. The stator pole pieces in each pair are mated together in an opposed relationship to form an annular space between them to receive an energizing winding, and the winding for each pair is of a different phase. Depending upon the number of phase assemblies, the machine can operate in more than two phases. The diameter of the rotor is between about 55 percent and about 75 percent of the motor diameter, and approximately 40 percent more torque is produced than with equivalent sized conventional motors.

Method of making a stepper motor

Stepper motor and method of making the same

An electric motor has an annular permanent magnetic rotor having rotor poles of alternating polarity around its circumference. The motor has an outer stator disposed concentrically around the outer periphery of the rotor which has an annular configuration and a plurality of axially extending salient magnetic poles of opposite polarity alternating around the outer stator's inner periphery. The motor also has an inner stator disposed concentrically within the inner periphery of the rotor which has an annular configuration and a plurality of axially extending salient magnetic poles of opposite polarity alternating around the inner stator's periphery. A separately energizable annular coil of wire disposed inside each stator energizes that stator's magnetic poles in response to sequential energization of each coil with electricity in different phase relationship with each other.

Low profile electric motor

A mounting plate assembly has provisions for reducing the motor noise transmission from a DC stepper motor or the like that has an associated reducing gear assembly. The mounting plate assembly is formed of a front plate which provides the bushings for the shafts of the reducing gears and on which an output bearing is mounted for journalling an output shaft. A generally discoid inner mounting plate of a first diameter is affixed adjacent the front plate and serves as a mount for holding the retaining cup or the overall stepper motor and gear assembly. An outer mounting plate, which has a second diameter smaller than the first diameter, serves for mounting the overall assembly in place, and has an aperture, favorably provided with a sleeve, coaxial with the output bearing. In order to provide acoustic isolation, a layer of resilient rubber is vulcanized in place between the inner and outer mounting plates. A portion of the gasket fills the annulus between the output bearing and the sleeve. This structure reduces the output noise from about 50 dB to about 31 dB. In other embodiments a suitable pressure sensitive or thermal sensitive adhesive may be substituted for the layer of resilient rubber.

Noiseless stepper motor

A linear stepper motor is provided with a feature to cause it to return to a zero position when current is cut off. The motor is formed of a stator armature assembly and a permanent magnet rotor assembly with poles thereof facing poles of the stator armature. The rotor assembly includes a rotor core formed as a nut with an axial threaded aperture extending therethrough. A shaft assembly includes a shaft screw mating with the rotor core nut, a front shaft affixed thereto, and a fixed sleeve overfitting the front shaft to permit axial motion thereof. A ball-and-groove arrangement in the front shaft and the sleeve prevents rotation of the shaft without impairing axial movement thereof. A spring causes return of the shaft to zero when there is no current applied to the stator armature. The spring can, for example, be a coil compression spring overfitting a portion of the shaft or a spiral torsion spring extending between the rotor and the stator armature.

Return-to-zero stepper motor

An electric motor having a stator with a plurality of pole pieces which are disposed in angularly spaced intervals about the axis of rotation of a cooperating rotor. Each stator pole piece has one or more teeth thereon. Each tooth has an inner peripheral surface which lies on the circumference of a circle having its center on the axis of rotation of the rotor. The teeth on each stator pole piece (which has a plurality of teeth) are spaced with a uniform pitch therebetween and the pitch on one stator pole piece is the same as the pitch on any other stator pole piece. One of the stator pole pieces and an adjacent stator pole piece about the axis of the rotor comprise a pole pair. Each two successive stator pole pieces disposed about the axis of the rotor comprise additional pole pairs. The plurality of teeth on one of the stator pole pieces in each of the pole pairs is shifted with respect to the plurality of teeth on the other stator pole piece in the same pair one half of the tooth pitch and the plurality of teeth on the adjacent pole pieces of adjacent pairs of stator pole pieces are shifted 1/2N of a tooth pitch where N is the number of phases of the motor.

Growing community of inventors

Wolcott, CT, United States of America

Charles W Hansen