Abstract: 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 ? and B and 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, ?, B and B are circumferentially shifted from corresponding small rotor teeth by a ¼ 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.

Abstract: A sliding hole is formed so that a screw portion can pass therethrough. Also, a seal member is provided at a portion, through which the screw portion placed in the sliding hole can pass and in which a sliding portion does not slide.

Abstract: In an automotive alternator according to the present invention, conductor segments of an inner winding portion and conductor segments of an outer winding portion have substantially the same shape.

Abstract: An electret actuator comprising a fixed substrate having driving electrodes of a plurality of phases arranged therein, a movable element arranged on the fixed substrate and made electret in similar polarity at predetermined pitches in portions which face the driving electrodes, and a driving control section configured to generate driving voltage patterns of a plurality of phases set at stages to move the movable element relative to the fixed substrate and a floating voltage pattern of a plurality of phases to float the movable element from the fixed substrate, and to apply the voltage patterns to the driving electrodes. The floating voltage pattern output from the driving control section has voltages similar to the electret charged polarity of the movable element.

Abstract: A motor-generator is disclosed, in which electromagnet coils are arranged at axially opposite ends of the stator, each to each end, while connections among winding sets are changed in response to the rpm of the rotor. This makes it possible to control the voltage, either at high speed or at low speed, thereby increasing the torque at low speed, or the torque on the rotor shaft at low speed and rendering the voltage stable. A rotor is comprised of a cylindrical magnetic path axially elongating to extent confronting the electromagnet coils, and a permanent-magnet member of more than one permanent-magnet piece extending axially over the magnetic path.