To provide an impact rotating tool capable of driving and controlling a motor while avoiding cost increase and enlargement.
By using variation of rotation speed peculiar to the impact rotating tool 1, a brushless motor 4 is driven at a maximum efficiency. In other words, based on a rotor position detection signal outputted from a rotor position detecting section 24, the rotation speed of the brushless motor 4 is calculated. An amplitude value and the center value of the amplitude of the variation of the rotating speed are calculated, and a load torque corresponding to the amplitude value and the center value of the amplitude is derived with a load torque table set from the amplitude value and the center value of the amplitude based on a measurement result measured in advance. A current phase corresponding to the load torque and the rotating speed is derived as a current phase β providing the maximum efficiency.
OKAMURA YUKIHIKO
SAKAMOTO KENJI
MIZUNO MITSUMASA
TERAURA KOICHI
INOUE HIROMIKI
Kyuichi Ueki
Takao Ito