Rotating electric machine

A rotating electric machine comprising:

• a stator having an armature coil wound on a stator core;
• and
• a rotor provided rotatably and having a field coil configured to be energized via brushes,
• wherein
• the rotor includes:
• a field core having a cylindrical boss portion on which the field coil is wound and a plurality of claw-shaped magnetic pole portions located on the stator side of the boss portion, the claw-shaped magnetic pole portions respectively forming magnetic poles polarities of which are alternately different in a circumferential direction;
• and
• a plurality of permanent magnets each of which is arranged between one circumferentially-adjacent pair of the claw-shaped magnetic pole portions with its axis of easy magnetization oriented in the circumferential direction, each of the permanent magnets having magnetic poles formed therein so as to match the polarities induced in the pair of claw-shaped magnetic pole portions by magnetomotive force of the field coil,
• wherein
• a relationship of 1.0<Ast/Af<1.6 is satisfied, where Af is a magnetic path cross-sectional area of the rotor and Ast is a magnetic path cross-sectional area of the stator, and
• a relationship of Af≤As is satisfied, where Af is the magnetic path cross-sectional area of the rotor and As is the area of a surface of each of the claw-shaped magnetic pole portions via which the claw-shaped magnetic pole portion exchanges magnetic flux with the stator core.

A brushless rotating electric machine comprising:

• a stator having an armature coil wound on a stator core;
• a rotor rotatably arranged to radially face the stator;
• and
• a housing that receives therein and supports the stator and the rotor,
• wherein
• the housing has a boss portion which is located on a radially opposite side to the stator and on which a field coil is wound,
• wherein
• the rotor includes:
• a field core having a plurality of magnetic pole portions located closer than the field coil to the stator, the magnetic pole portions respectively forming magnetic poles polarities of which are alternately different in a circumferential direction;
• and
• a plurality of permanent magnets each of which is arranged between one circumferentially-adjacent pair of the magnetic pole portions with its axis of easy magnetization oriented in the circumferential direction, each of the permanent magnets having magnetic poles formed therein so as to match the polarities induced in the pair of magnetic pole portions by magnetomotive force of the field coil,
• wherein
• a d-axis magnetic circuit and a magnet magnetic circuit share a magnetic path in at least parts thereof,
• along the d-axis magnetic circuit, magnetic flux generated by the magnetomotive force of the field coil flows through the boss portion, one pair of the magnetic pole portions and the stator core,
• along the magnet magnetic circuit, magnetic flux generated by magnetic force of a corresponding one of the permanent magnets flows,
• a relationship of Af<As is satisfied, where Af is a magnetic path cross-sectional area of the rotor and As is the area of a surface of each of the magnetic pole portions via which the magnetic pole portion exchanges magnetic flux with the stator core, and
• a relationship of Ast>Af is satisfied, where Ast is a magnetic path cross-sectional area of the stator and Af is the magnetic path cross-sectional area of the rotor.

A brushless rotating electric machine comprising:

• a stator having an armature coil wound on a stator core;
• a rotor rotatably arranged to radially face the stator;
• and
• a housing that receives therein and supports the stator and the rotor,
• wherein
• the housing has a boss portion which is located on a radially opposite side to the stator and on which a field coil is wound,
• wherein
• the rotor includes:
• a field core having a plurality of magnetic pole portions located closer than the field coil to the stator, the magnetic pole portions respectively forming magnetic poles polarities of which are alternately different in a circumferential direction;
• and
• a plurality of permanent magnets each of which is arranged between one circumferentially-adjacent pair of the magnetic pole portions with its axis of easy magnetization oriented in the circumferential direction, each of the permanent magnets having magnetic poles formed therein so as to match the polarities induced in the pair of magnetic pole portions by magnetomotive force of the field coil,
• wherein
• a relationship of 1.0<Ast/Af<1.6 is satisfied, where Af is a magnetic path cross-sectional area of the rotor and Ast is a magnetic path cross-sectional area of the stator, and
• a relationship of Af≤As is satisfied, where Af is the magnetic path cross-sectional area of the rotor and As is the area of a surface of each of the magnetic pole portions via which the magnetic pole portion exchanges magnetic flux with the stator core.