Brushless motor and electric power steering apparatus equipped with the brushless motor

A brushless motor comprising:

• a stator including a plurality of armatures;
• and
• a rotor provided in operative combination with said stator and including a plurality of permanent magnets positioned on and along a circumference thereof,
• each of said permanent magnets having a sectional shape asymmetrical, along the circumference of said rotor, with respect to a predetermined imaginary reference line extending in a radial direction of said rotor, each of said permanent magnets being divided in an axial direction of said rotor into a plurality of divided magnet members, axially adjacent ones of the divided magnet members in each of said permanent magnets being positioned on said rotor in such a manner that the asymmetrical sectional shapes of the axially adjacent divided magnet members present opposite orientations.

A brushless motor comprising:

• a stator including a plurality of armatures;
• and
• a rotor provided in operative combination with said stator and including a plurality of permanent magnets positioned on and along a circumference thereof,
• each of said permanent magnets being magnetized in a direction inclined, in a circumferential direction of said rotor, with respect to a surface thereof secured to said rotor, each of said permanent magnets being divided in an axial direction of said rotor into a plurality of divided magnet members, adjacent ones of the divided magnet members in each of said permanent magnets being positioned on said rotor so that magnetizing directions of the divided magnet members are opposite to each other.

An electric power steering apparatus for use in a motor vehicle comprising:

• a steering system extending from a steering wheel to steerable road wheels;
• a steering torque sensor for detecting steering torque produced on said steering wheel, to thereby generate a steering torque detection signal;
• a brushless motor for generating steering assist torque under control of a control unit on the basis of the steering torque detection signal generated by said steering torque sensor;
• and
• a torque transmission mechanism for transmitting the steering assist torque, generated by said brushless motor, to said steering system,
• said brushless motor comprising:
• a stator including a plurality of armatures;
• a rotor provided in operative combination with said stator and including a plurality of permanent magnets positioned on and along a circumference thereof;
• and
• a cover formed of a magnetic material into a cylindrical shape having a relatively small wall thickness, said cover covering a surface of said stator opposed to said rotor, said cover having a plurality of slits formed therein to incline with respect to a rotational axis of said rotor.

An electric power steering apparatus for use in a motor vehicle comprising:

• a steering system extending from a steering wheel to steerable road wheels;
• a steering torque sensor for detecting steering torque produced on said steering wheel, to thereby generate a steering torque detection signal;
• a brushless motor for generating steering assist torque under control of a control unit on the basis of the steering torque detection signal generated by said steering torque sensor;
• and
• a torque transmission mechanism for transmitting the steering assist torque, generated by said brushless motor, to said steering system
• said brushless motor comprising:
• a stator including a plurality of armatures;
• and
• a rotor provided inoperative combination with said stator and including a plurality of permanent magnets positioned on and along a circumference thereof,
• each of said permanent magnets having an asymmetrical sectional shape, along the circumference of said rotor, with respect to a predetermined imaginary reference line extending in a radial direction of said rotor, each of said permanent magnets being divided in an axial direction of said rotor into a plurality of divided magnet members, axially adjacent ones of the divided magnet members in each of said permanent magnets being positioned on said rotor in such a manner that the asymmetrical sectional shapes of the axially adjacent divided magnet members present opposite orientations.

An electric power steering apparatus for use in a motor vehicle comprising:

• a steering system extending from a steering wheel to steerable road wheels;
• a steering torque sensor for detecting steering torque produced on said steering wheel, to thereby generate a steering torque detection signal;
• a brushless motor for generating steering assist torque under control of a control unit on the basis of the steering torque detection signal generated by said steering torque sensor;
• and
• a torque transmission mechanism for transmitting the steering assist torque, generated by said brushless motor, to said steering system
• said brushless motor comprising:
• a stator including a plurality of armatures;
• and
• a rotor provided in operative combination with said stator and including a plurality of permanent magnets positioned on and along a circumference thereof,
• each of said permanent magnets being magnetized in a direction inclined, in a circumferential direction of said rotor, with respect to a surface thereof secured to said rotor, each of said permanent magnets being divided in an axial direction of said rotor into a plurality of divided magnet members, adjacent ones of the divided magnet members in each of said permanent magnets being positioned on said rotor so that magnetizing directions of the divided magnet members are opposite to each other.