For the purpose of preventing demagnetization of a magnet (32) without any
cost increase and improving the max torque and the efficiency of an
electric motor (20) by suppressing deterioration of magnetic flux density,
a permanent magnet-type electric motor (20) comprises a stator (21) and a
rotor (25) disposed in the stator (21), in which a plurality of permanent
magnets (32), (32) forming a magnetic pole are inserted in magnet
insertion portions (31), (31) of a yoke (26) in such manner that the
magnets (32), (32) form in line in the circumferential direction thereof,
wherein each magnet (32) is divided into a central magnet (33) that is
positioned at the central portion in the width direction of the magnet
insertion portion (31) and end magnets (34), (34) that are positioned at
end portions of the magnet insertion portion (31), and the end magnets
(34), (34) have greater coercive forces than the central magnet (33),
whereas the central magnet (33) has a greater magnetic flux density than
the end magnets (34), (34). Because the end magnets (34), (34) easy to be
demagnetized by the reverse magnetic filed caused by the stator current
have greater coercive forces, demagnetization of the magnet (32) can be
prevented as a whole. In the meantime, because the central magnet (33)
difficult to be demagnetized has a greater magnetic flux density, the max
torque and the efficiency of the electric motor (20) can be improved by
such great magnetic flux density.
