Japan Servo Co.,ltd.

Koki Isozaki

Masafumi Sakamoto

Kazuo Ohnishi

Toshimi Abukawa

A three-phase hybrid type stepping motor of the present invention comprises a stator, a rotor arranged concentrically with the stator and with an air gap therebetween, six stator poles extending radially and formed at a regular pitch on the inner peripheral surface of an annular stator yoke, each of the stator poles having a plurality of small stator teeth at the tip end thereof, the rotor having two splitted rotor elements and a permanent magnet held therebetween and magnetized so as to form N and S poles in the axial direction thereof, fifty of small rotor teeth formed at a regular pitch on the outer peripheral surface of each of the rotor elements, the two splitted rotor elements being shifted from each other in angular position by a &frac12; pitch of the small rotor teeth, wherein a permeance distribution of the small stator teeth is a vernier pitch balanced by a six or three order harmonic wave, and a ratio of the width of the pole tooth to the rotor teeth pitch is set to 0.35-0.45.

Three-phase hybrid type stepping motor

The permeance between the small teeth provided on the stator magnetic pole and the rotor magnetic pole may be varied regularly according to the rotation of the rotor. The small stator teeth provided on the tip end of each stator magnetic pole are divided into sets of two or three small stator teeth and at least one pitch of the adjacent teeth is different from the other pitch of the other adjacent teeth, so that the vector sum of the quaternary harmonics of permeance in each set is substantially zero. The small stator teeth formed on the tip end of the stator pole are composed of two sets of three small stator teeth, and at least one pitch of the adjacent teeth is different from the other pitch of the other adjacent teeth, so that a vector sum of the tertiary harmonics of permeance of the three small stator teeth included in each of sets becomes substantially zero, and that a vector sum of permeances of axialsymmetric two small stator teeth on the quaternary harmonic plane of two sets becomes substantially zero.

Two-phase hybrid type stepping motor

In the three-phase hybrid type stepping motor according to the present invention, the small stator teeth formed on the tip end of the stator pole are classified to sets of two or three small teeth, the third harmonic vector sum of the permeances of the small teeth in each set is determine to substantially zero, and the third, fifth and sixth harmonic vector sum of the permeances of the small teeth of the sets is determine to substantially zero, under the consideration that the permeances between the small teeth of the stator magnetic pole and the rotor are varied according to the rotation of the rotor and that the permeances are varied regularly.

A permanent magnet type stepping motor wherein number of magnetic poles provided radially on the inside periphery of a stator is 16, number of pole teeth provided on a rotor poles is (z) (wherein z=16 m.+-.4; (m) denotes a positive integer), 14 poles among 16 have pitch of (22.5.-+.45/z).degree. between their own pole teeth and corresponding pole teeth of adjacent poles and other two poles have pitch of (22.5.+-.315/z).degree. between their own pole teeth and corresponding pole teeth of adjacent poles.

Growing community of inventors

Gunma, Japan

Koki Isozaki