PURPOSE: To compensate non-spark zone moving phenomenon and to prevent a brush from causing the spark by strengthening field magnetomotive force larger than the commutating pole magnetomotive force in a base rotating speed and by weakening the former than the latter.
CONSTITUTION: In reinforced field system (in a base rotating speed), leakage flux LP going through a magnetic bridge 10A is utilized as commutating pole flux quantity. In weak field system (in a maximum rotation speed), a part of the flux IP3 of the commutating pole flux ZP going through the magnetic bridge 10A is utilized as the main flux MP. Thus, the commutating flux quantity from the tip of a commutating pole core 8 to an armature can be changed drastically in the reinforced field system and in the weakened field system. As a result, the commutating pole flux quantity in the maximum rotating speed can remarkably be reduced against the commutating pole flux quantity in the base rotating speed. This moving phenomenon of non-spark zone in a DC machine can thereby be compensated and the occurrence of spark from a brush can be prevented.
TAWARA KAZUO
MIYASHITA KUNIO
ETO TETSUO
SUZUKI NOBUTAKA
HITACHI SETSUBI ENG KK
| JPH0787686A | 1995-03-31 |