Japan Servo Co.,ltd.

Hitachi, Ltd.

Kazuo Ohnishi

Shoji Ohiwa

Masafumi Sakamoto

Toshimi Abukawa

Yasuaki Motegi

Koki Isozaki

Tokio Sekiguchi

Hiroshi Kimura

Fumio Tajima

Yuji Enomoto

Shigeki Morinaga

Hiroshi Katayama

Hiroshi Kanazawa

Nobuyoshi Mutoh

Nobuyoshi Tsuboi

Hideki Nihei

Masahiro Mimura

Hitoshi Ishii

Yuji Takagai

Sachio Hatori

Junichi Ikeda

Atushi Yamamoto

Noriyoshi Kikuchi

Misao Ichikawa

Keiichi Abe

Youji Unoki

Shinji Shimizu

Tomokazu Uchiyama

Yoichi Nagata

Hideo Saito

Kouji Yoneda

Yukinori Kurita

Hideaki Suzuki

Kiyomichi Inoshita

A multi-polar rotary machine comprises a cylindrical outer rotor arranged concentrically with the stator and with an air gap therebetween. The stator has two spaced stator elements and a ring shaped permanent magnet held between the stator elements and magnetized so as to form N and S poles in the axial direction of the stator. Small axially separated stator teeth A and &#x100; andand B are formed on the outer peripheral surface of the spaced stator elements. Stator windings for A phase and B phase are wound around the respective stator elements. The small stator teeth A, &#x100;,and B are circumferentially shifted from corresponding small rotor teeth by a &#xbc; pitch of the small stator teeth, respectively. Each of the stator and rotor is formed of pressed powder comprising a soft magnetic material at least one of a resin and an inorganic material.

Motor having shifted teeth of pressed powder construction

A multi-polar rotary machine comprises a and a cylindrical outer rotor arranged concentrically with the stator and with an air gap therebetween. The stator has two splitted stator elements and a ring shaped permanent magnet held between the stator elements and magnetized so as to form N and S poles in the axial direction of the stator. Small axially separated stator teeth A and &#x100; andand B are formed on the outer peripheral surface of the splitted stator elements. Stator windings for A phase and B phase are wound around the respective stator elements. The small stator teeth A, &#x100;,and B are circumferentially shifted from corresponding small rotor teeth by a &#xbc; pitch of the small stator teeth, respectively. Each of the stator and rotor is formed of pressed powder consisting of soft magnetic material, and of resin and/or inorganic material. A ratio of a thickness of the small stator teeth &#x100; in the axial direction of the stator to a thickness of the small stator teeth A in the axial direction of the stator or a ratio of a thickness of the small stator teethin the axial direction of the stator to a thickness of the small stator teeth B in the axial direction of the stator is set to a value smaller than 1 so as to equalize substantially in mean permeance both small stator teeth A and &#x100; orand B to each other.

A two-phase or three-phase claw-pole type rotary machine comprises two or three coaxially arranged single phase rotary machine elements. Each of the rotary machine elements has a magnet rotor, a claw-pole type stator, and an annular stator winding. Claw poles of the stator are divided into a plurality of blocks and are circumferentially separated from one another. A distance between adjacent claw poles of the same polarity in each block is (&#x3b2;&#x2212;&#x394;&#x3b2;), substantially, where &#x3b2;is a reference pitch when the claw poles of the same polarity are arranged equidistantly apart from one another in a range of 360&#xb0;, &#x394;&#x3b2; is &#x3c0;/2q, or &#x3c0;/3q and q is a number of claw poles of the same polarity in each block. The first and second rotary machine elements are circumferentially shifted from each other by 90&#xb0; or 120&#xb0;.

Multi-phase claw-pole type rotary machine

A permanent magnet motor comprising a permanent magnet and an armature having a plurality of winding grooves facing the permanent magnet with an air gap therebetween. The armature has a plurality of auxiliary grooves on a magnetic pole surface thereof, wherein a composite of two vectors of cogging torque generated by the auxiliary grooves is deviated by 180&deg; or 120&deg; from a vector of cogging torque generated by the winding grooves in the sixth harmonic plane, and wherein a width of a portion of an air gap magnetic flux density waveform that includes a value that is more than 90% of a peak value of the air gap magnetic flux density waveform is less than 80% or 86% of a width of a pole pitch portion of the air gap magnetic flux density waveform. Each vector of cogging torque generated by each of the plurality of auxiliary grooves is deviated by 180&deg; or 120&deg; from a vector of cogging torque generated by the winding grooves in the sixth harmonic plane, respectively, and wherein a width of a portion of an air gap magnetic flux density waveform that includes a value that is more than 90% of a peak value of the air gap magnetic flux density waveform is less than 80% or 86% of a width of a pole pitch portion of the air gap magnetic flux density waveform.

Permanent magnet motor

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

A brushless DC motor wherein a rotor has a motor shaft, a rotor yoke mounted on the motor shaft, and a ring-shaped magnet magnetized so as to have a plurality of magnet poles in the circumferential direction thereof, and held by the rotor yoke. A stator has first and second stator yokes each having main magnetic poles extending in the radial direction from the center thereof, magnetic pole pieces extending in the vertical direction from tip ends of the main magnetic poles along an inner peripheral surface of the ring-shaped magnet, a center yoke surrounding the motor shaft for connecting magnetically said first and second stator yokes, a winding assembly having an annular winding, and a printed wiring board, on which the annular winding, a electromagnetic conversion element and a driving circuit are mounted.

Brushless DC motor

A permanent magnet motor having a stator and a permanent magnet rotor facing the stator with a gap therebetween, the stator having a plurality of stator magnetic poles extending radially toward a peripheral surface of the rotor, s number of small stator teeth formed on a tip end of each of the magnetic poles, and exciting windings of m phases wound around the stator magnetic poles. The rotor having a cylindrical permanent magnet having pieces of N pole and pieces of S pole arranged alternately in a peripheral direction thereof at equal pitches, wherein a pitch of the small stator teeth is 1&plusmn;1/(2ms) times larger than a pitch of the rotor magnetic pole pairs. The width of the small stator tooth is 37&tilde;47% of the magnetic pole pitch. A depth of the groove formed between the adjacent small stator teeth is more than 15 times larger than the length of the air gap between the stator and the rotor.

The magnetic pole position detector for an electric motor comprises a detection rotor, a detection stator, and magnetic flux concentration tips and magneto electro transducers. The detection rotor is fixed to an axis of rotation of the motor and comprised of disc-like rotors having first toothlike protrusions and a permanent magnet. The disc-like rotors are assembled so as to make the first toothlike protrusions coincide in the axial direction and the permanent magnet is fixed between the disc-like rotors. The detection stator is comprised of stator cores comprised of an annular yoke and stator teeth formed at regular intervals on the former. Second toothlike protrusions are formed on the inner end of the stator teeth. The stator cores are assembled with a gap in the axial direction so as to make respective second toothlike protrusions coincide in the axial direction. The magnetic flux concentration tips and the magneto electro transducers are placed in the gaps in the axial direction. The detection rotor and the detection stator are assembled with a gap in the radial direction. The magnetic pole position is obtained by detecting the magnetic flux flowing through the stator teeth that varies in accordance the rotation of the detection rotor.

Magnetic pole position detector for an electric 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 electric rotating machine with a concentrated winding stator, including a stator having a plurality of stator magnetic poles formed so as to extend radially from an annular yoke portion of a stator iron core, and windings mounted on the stator magnetic poles; and a rotor having a permanent magnet with a plurality of magnetic poles and rotatably held so as to face the stator through an air gap; wherein each of the stator magnetic poles has a straight shape having a width which is made constant over a whole length, small grooves are formed in each of the stator magnetic poles in symmetrical positions on opposite sides and near a top end portion of the stator magnetic pole, a bottom portion of each slot portion defined by adjacent ones of the stator magnetic poles and the yoke is formed triangularly, each of the stator winding is constituted so that a winding having a predetermined number of turns and winding being formed so as to be fittable to each of the stator magnetic poles is mounted on the stator magnetic pole through an insulator, and wedges are fitted to the small grooves formed in the stator magnetic poles.

Permanent-magnet revolving electrodynamic machine with a concentrated winding stator

An electric rotary machine has a concentrated winding stator and a rotor facing the stator with a gap therebetween. The stator has M number of stator magnetic poles extending in the radial direction from an annular yoke, pole pieces each extending in the circumferential direction of the rotor from the tip end of each of the stator magnetic poles, and windings wound around the stator magnetic poles. The rotor having a permanent magnet with P number magnetic poles, wherein P:M&equals;6n&minus;2:6n, or P:M&equals;6n&plus;2:6n, where n is an integer not less than 2, and the figure of each of the pole pieces is so determined that a gap formed between the pole piece and the rotor is increased going toward the both ends of the pole piece.

Electric rotary machine having concentrated winding stator

A motor has a stator and a rotor, the stator having cores and drive coils which generate magnetic fields for rotating the rotor. The stator also has a yoke surrounding the rotor and the rotor is positioned such that it is closer to one part of the outer periphery of the yoke than another part of the outer periphery of the yoke. Such a motor is particularly suitable for use in a disk drive unit as a spindle motor for rotating the disk. Then an actuator for moving a head may be located adjacent the part of the outer periphery of the yoke which is closest to the rotor. This permits the head to approach closely the axis of rotation of the disk without the spindle motor interferring with the movement of the head. The continuous yoke prevents magnetic flux leakage from the spindle motor interferring with the actuator. The actuator may itself have a yoke integral with the yoke of the spindle motor, and/or other components in common.

Disk drive unit having motor components in a compact arrangement

An absolute encoder wherein tracks are arranged side-by-side on a magnetic drum in the axial direction thereof, and absolute patterns of circulatory random sequence codes are divided and recorded on the tracks, respectively. An additional track for generating sinewaves of two phases in synchronism with the reading of the absolute patterns is provided on the magnetic drum, so that an output can be obained by combining a coarse value of an absolute position obtained from the tracks and a fine value of an absolute position obtained from the additional track. The absolute patterns are detected from the two tracks recorded on the magnetic drum by magnetic resistive elements connected with each other to form circuits each having a three-terminal. Terminals of the magnetic resistive elements are connected through a common line with an electric power source in order to prevent the lines from being crossed.

Growing community of inventors

Gunma, Japan

Kazuo Ohnishi