Japan Servo Co.,ltd.

Tokio Sekiguchi

Kazuo Ohnishi

Toshimi Abukawa

Misao Ichikawa

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

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

Tokio Sekiguchi