| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a downsized and light-weight electric motor having its rotational speed freely switchable while a decrease in its drive efficiency is suppressed. <P>SOLUTION: A so-called disk type commutator 20 is provided in a three brush motor which can switch the rotational speed of an armature shaft 13 between a low speed drive and a high speed drive. The commutator 20 is formed in disk shape by arranging a plurality of pieces of substantially fan-shaped segment 23 side by side in the rotating direction of the armature shaft 13. A sliding surface 23a on which each brush 30 energized in the axial direction slides is formed on the axial end surface of each segment 23, and each brush 30 is arranged while being displaced axially from the commutator 20. Since it is not necessary to secure a space for arranging each brush 30 on the radial outside of the commutator 20, the outer diameter R1 of the commutator 20 is formed to be arge enough. <P>COPYRIGHT: (C)2011,JPO&INPIT</p> |
