| 摘要 |
PROBLEM TO BE SOLVED: To obtain a small, lightweight and high output brushless motor in which heating of rotor is suppressed by composing a rotor magnet of a rare earth material and making a plurality of axial trenches in the outer circumference of rotor magnet. SOLUTION: A rotor 6 is fixed with a tubular rotor core 8 and a rotor magnet 9 is fitted thereon. The rotor magnet 9 is composed of a sintered rare earth material and even number of trenches 10 are made axially in the outer circumference thereof. When the stator coil is conducted with an appropriate conduction pattern, the rotor 6 rotates to generate a cooling air well because of the trenches 10 made in the rotor magnet 9. Generation of eddy current in the rotor magnet 9 is confined within a region sectioned by each trench 10 and thereby the eddy current is subdivided and reduced. Consequently, generation of heat is reduced and the cooling effect is enhanced thus suppressing the heating of rotor magnet 9. |
