| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an electric power tool which can prevent burning of a motor without increasing power consumption. <P>SOLUTION: The electric power tool includes a motor 3, a semiconductor element (triac) 27 that regulates an AC voltage applied to the motor 3, a rotating speed setting means (32) that sets the rotating speed of the motor 3, a rotating speed detecting means (5, 6) that detects the rotating speed of the motor 3, and a control means 23 that compares detection signals output from the rotating speed detecting means with rotating speed setting signals set by the rotating speed setting means and increases or reduces a set conduction angle. When the increased conduction angle exceeds a limiting conduction angle corresponding to the set rotating speed for a given period of time, the control means 23 determines that the motor 3 is in an overcurrent state. When this determination has been made, the control means 23 controls the motor 3 so that the motor 3 is stopped, or the rotating speed of the motor is lowered. The relationship between the set rotating speed of the motor 3 and the limiting conduction angle which causes an overcurrent state is previously stored in a storage means within the control means 23. <P>COPYRIGHT: (C)2010,JPO&INPIT |
