Patent ID: 8198839
Filing Date: 2012-06-12
Classification: B25F,E04G,H02P,Y10S

Abstract:
1. An electric power tool in which a working part is actuated by repeating rotation of a brushless motor in a normal direction and in a reverse direction one or more times, the electric tool comprising: at least three sensors for detecting a position of a rotor of the brushless motor, wherein either one or both of a rotation number and a rotation position of the motor is measured by a detection signal of one of the sensors, a working state of the working part is recognized from results of a measurement, the sensors are disposed at positions advanced by an electrical angle of 30°±θ° from an intermediate position between respective stator teeth, a control part for controlling the rotation of the motor controls a driving signal for driving the motor based on detection results of the position of the rotor by the sensors, and the control part selects a detection signal of the sensors so that a relation between the rotor and the detection signal of the sensors is equivalent in either of the normal rotation and the reverse rotation of the rotor.